RFC3209 - RSVP-TE: Extensions to RSVP for LSP Tunnels

Network Working Group D. AwdUChe

Request for Comments: 3209 Movaz Networks, Inc.

Category: Standards Track L. Berger

D. Gan

Juniper Networks, Inc.

T. Li

Procket Networks, Inc.

V. Srinivasan

Cosine Communications, Inc.

G. Swallow

Cisco Systems, Inc.

December 2001

RSVP-TE: Extensions to RSVP for LSP Tunnels

Status of this Memo

This document specifies an Internet standards track protocol for the

Internet community, and requests discussion and suggestions for

improvements. Please refer to the current edition of the "Internet

Official Protocol Standards" (STD 1) for the standardization state

and status of this protocol. Distribution of this memo is unlimited.

Abstract

This document describes the use of RSVP (Resource Reservation

Protocol), including all the necessary extensions, to establish

label-switched paths (LSPs) in MPLS (Multi-Protocol Label Switching).

Since the flow along an LSP is completely identified by the label

applied at the ingress node of the path, these paths may be treated

as tunnels. A key application of LSP tunnels is traffic engineering

with MPLS as specified in RFC2702.

We propose several additional objects that extend RSVP, allowing the

establishment of eXPlicitly routed label switched paths using RSVP as

a signaling protocol. The result is the instantiation of label-

switched tunnels which can be automatically routed away from network

failures, congestion, and bottlenecks.

Contents

1 Introduction .......................................... 3

1.1 Background ............................................. 4

1.2 Terminology ............................................ 6

2 Overview .............................................. 7

2.1 LSP Tunnels and Traffic Engineered Tunnels ............. 7

2.2 Operation of LSP Tunnels ............................... 8

2.3 Service Classes ........................................ 10

2.4 Reservation Styles ..................................... 10

2.4.1 Fixed Filter (FF) Style ................................ 10

2.4.2 Wildcard Filter (WF) Style ............................. 11

2.4.3 Shared Explicit (SE) Style ............................. 11

2.5 Rerouting Traffic Engineered Tunnels ................... 12

2.6 Path MTU ............................................... 13

3 LSP Tunnel related Message Formats ..................... 15

3.1 Path Message ........................................... 15

3.2 Resv Message ........................................... 16

4 LSP Tunnel related Objects ............................. 17

4.1 Label Object ........................................... 17

4.1.1 Handling Label Objects in Resv messages ................ 17

4.1.2 Non-support of the Label Object ........................ 19

4.2 Label Request Object ................................... 19

4.2.1 Label Request without Label Range ...................... 19

4.2.2 Label Request with ATM Label Range ..................... 20

4.2.3 Label Request with Frame Relay Label Range ............. 21

4.2.4 Handling of LABEL_REQUEST .............................. 22

4.2.5 Non-support of the Label Request Object ................ 23

4.3 Explicit Route Object .................................. 23

4.3.1 Applicability .......................................... 24

4.3.2 Semantics of the Explicit Route Object ................. 24

4.3.3 Subobjects ............................................. 25

4.3.4 Processing of the Explicit Route Object ................ 28

4.3.5 Loops .................................................. 30

4.3.6 Forward Compatibility .................................. 30

4.3.7 Non-support of the Explicit Route Object ............... 31

4.4 Record Route Object .................................... 31

4.4.1 Subobjects ............................................. 31

4.4.2 Applicability .......................................... 34

4.4.3 Processing RRO ......................................... 35

4.4.4 Loop Detection ......................................... 36

4.4.5 Forward Compatibility .................................. 37

4.4.6 Non-support of RRO ..................................... 37

4.5 Error Codes for ERO and RRO ............................ 37

4.6 Session, Sender Template, and Filter Spec Objects ...... 38

4.6.1 Session Object ......................................... 39

4.6.2 Sender Template Object ................................. 40

4.6.3 Filter Specification Object ............................ 42

4.6.4 Reroute and Bandwidth Increase Procedure ............... 42

4.7 Session Attribute Object ............................... 43

4.7.1 Format without resource affinities ..................... 43

4.7.2 Format with resource affinities ........................ 45

4.7.3 Procedures applying to both C-Types .................... 46

4.7.4 Resource Affinity Procedures .......................... 48

5 Hello Extension ........................................ 49

5.1 Hello Message Format ................................... 50

5.2 HELLO Object formats ................................... 51

5.2.1 HELLO REQUEST object ................................... 51

5.2.2 HELLO ACK object ....................................... 51

5.3 Hello Message Usage .................................... 52

5.4 Multi-Link Considerations .............................. 53

5.5 Compatibility .......................................... 54

6 Security Considerations ................................ 54

7 IANA Considerations .................................... 54

7.1 Message Types .......................................... 55

7.2 Class Numbers and C-Types .............................. 55

7.3 Error Codes and Globally-Defined Error Value Sub-Codes . 57

7.4 Subobject Definitions .................................. 57

8 Intellectual Property Considerations ................... 58

9 Acknowledgments ........................................ 58

10 References ............................................. 58

11 Authors' Addresses ..................................... 60

12 Full Copyright Statement ............................... 61

1. Introduction

Section 2.9 of the MPLS architecture [2] defines a label distribution

protocol as a set of procedures by which one Label Switched Router

(LSR) informs another of the meaning of labels used to forward

traffic between and through them. The MPLS architecture does not

assume a single label distribution protocol. This document is a

specification of extensions to RSVP for establishing label switched

paths (LSPs) in MPLS networks.

Several of the new features described in this document were motivated

by the requirements for traffic engineering over MPLS (see [3]). In

particular, the extended RSVP protocol supports the instantiation of

explicitly routed LSPs, with or without resource reservations. It

also supports smooth rerouting of LSPs, preemption, and loop

detection.

The LSPs created with RSVP can be used to carry the "Traffic Trunks"

described in [3]. The LSP which carries a traffic trunk and a

traffic trunk are distinct though closely related concepts. For

example, two LSPs between the same source and destination could be

load shared to carry a single traffic trunk. Conversely several

traffic trunks could be carried in the same LSP if, for instance, the

LSP were capable of carrying several service classes. The

applicability of these extensions is discussed further in [10].

Since the traffic that flows along a label-switched path is defined

by the label applied at the ingress node of the LSP, these paths can

be treated as tunnels, tunneling below normal IP routing and

filtering mechanisms. When an LSP is used in this way we refer to it

as an LSP tunnel.

LSP tunnels allow the implementation of a variety of policies related

to network performance optimization. For example, LSP tunnels can be

automatically or manually routed away from network failures,

congestion, and bottlenecks. Furthermore, multiple parallel LSP

tunnels can be established between two nodes, and traffic between the

two nodes can be mapped onto the LSP tunnels according to local

policy. Although traffic engineering (that is, performance

optimization of operational networks) is expected to be an important

application of this specification, the extended RSVP protocol can be

used in a much wider context.

The purpose of this document is to describe the use of RSVP to

establish LSP tunnels. The intent is to fully describe all the

objects, packet formats, and procedures required to realize

interoperable implementations. A few new objects are also defined

that enhance management and diagnostics of LSP tunnels.

The document also describes a means of rapid node failure detection

via a new HELLO message.

All objects and messages described in this specification are optional

with respect to RSVP. This document discusses what happens when an

object described here is not supported by a node.

Throughout this document, the discussion will be restricted to

unicast label switched paths. Multicast LSPs are left for further

study.

1.1. Background

Hosts and routers that support both RSVP [1] and Multi-Protocol Label

Switching [2] can associate labels with RSVP flows. When MPLS and

RSVP are combined, the definition of a flow can be made more

flexible. Once a label switched path (LSP) is established, the

traffic through the path is defined by the label applied at the

ingress node of the LSP. The mapping of label to traffic can be

accomplished using a number of different criteria. The set of

packets that are assigned the same label value by a specific node are

said to belong to the same forwarding equivalence class (FEC) (see

[2]), and effectively define the "RSVP flow." When traffic is mapped

onto a label-switched path in this way, we call the LSP an "LSP

Tunnel". When labels are associated with traffic flows, it becomes

possible for a router to identify the appropriate reservation state

for a packet based on the packet's label value.

The signaling protocol model uses downstream-on-demand label

distribution. A request to bind labels to a specific LSP tunnel is

initiated by an ingress node through the RSVP Path message. For this

purpose, the RSVP Path message is augmented with a LABEL_REQUEST

object. Labels are allocated downstream and distributed (propagated

upstream) by means of the RSVP Resv message. For this purpose, the

RSVP Resv message is extended with a special LABEL object. The

procedures for label allocation, distribution, binding, and stacking

are described in subsequent sections of this document.

The signaling protocol model also supports explicit routing

capability. This is accomplished by incorporating a simple

EXPLICIT_ROUTE object into RSVP Path messages. The EXPLICIT_ROUTE

object encapsulates a concatenation of hops which constitutes the

explicitly routed path. Using this object, the paths taken by

label-switched RSVP-MPLS flows can be pre-determined, independent of

conventional IP routing. The explicitly routed path can be

administratively specified, or automatically computed by a suitable

entity based on QoS and policy requirements, taking into

consideration the prevailing network state. In general, path

computation can be control-driven or data-driven. The mechanisms,

processes, and algorithms used to compute explicitly routed paths are

beyond the scope of this specification.

One useful application of explicit routing is traffic engineering.

Using explicitly routed LSPs, a node at the ingress edge of an MPLS

domain can control the path through which traffic traverses from

itself, through the MPLS network, to an egress node. Explicit

routing can be used to optimize the utilization of network resources

and enhance traffic oriented performance characteristics.

The concept of explicitly routed label switched paths can be

generalized through the notion of abstract nodes. An abstract node

is a group of nodes whose internal topology is opaque to the ingress

node of the LSP. An abstract node is said to be simple if it

contains only one physical node. Using this concept of abstraction,

an explicitly routed LSP can be specified as a sequence of IP

prefixes or a sequence of Autonomous Systems.

The signaling protocol model supports the specification of an

explicit path as a sequence of strict and loose routes. The

combination of abstract nodes, and strict and loose routes

significantly enhances the flexibility of path definitions.

An advantage of using RSVP to establish LSP tunnels is that it

enables the allocation of resources along the path. For example,

bandwidth can be allocated to an LSP tunnel using standard RSVP

reservations and Integrated Services service classes [4].

While resource reservations are useful, they are not mandatory.

Indeed, an LSP can be instantiated without any resource reservations

whatsoever. Such LSPs without resource reservations can be used, for

example, to carry best effort traffic. They can also be used in many

other contexts, including implementation of fall-back and recovery

policies under fault conditions, and so forth.

1.2. Terminology

The key Words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",

"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this

document are to be interpreted as described in RFC2119 [6].

The reader is assumed to be familiar with the terminology in [1], [2]

and [3].

Abstract Node

A group of nodes whose internal topology is opaque to the ingress

node of the LSP. An abstract node is said to be simple if it

contains only one physical node.

Explicitly Routed LSP

An LSP whose path is established by a means other than normal IP

routing.

Label Switched Path

The path created by the concatenation of one or more label

switched hops, allowing a packet to be forwarded by swapping

labels from an MPLS node to another MPLS node. For a more precise

definition see [2].

LSP

A Label Switched Path

LSP Tunnel

An LSP which is used to tunnel below normal IP routing and/or

filtering mechanisms.

Traffic Engineered Tunnel (TE Tunnel)

A set of one or more LSP Tunnels which carries a traffic trunk.

Traffic Trunk

A set of flows aggregated by their service class and then placed

on an LSP or set of LSPs called a traffic engineered tunnel. For

further discussion see [3].

2. Overview

2.1. LSP Tunnels and Traffic Engineered Tunnels

According to [1], "RSVP defines a 'session' to be a data flow with a

particular destination and transport-layer protocol." However, when

RSVP and MPLS are combined, a flow or session can be defined with

greater flexibility and generality. The ingress node of an LSP can

use a variety of means to determine which packets are assigned a

particular label. Once a label is assigned to a set of packets, the

label effectively defines the "flow" through the LSP. We refer to

such an LSP as an "LSP tunnel" because the traffic through it is

opaque to intermediate nodes along the label switched path.

New RSVP SESSION, SENDER_TEMPLATE, and FILTER_SPEC objects, called

LSP_TUNNEL_IPv4 and LSP_TUNNEL_IPv6 have been defined to support the

LSP tunnel feature. The semantics of these objects, from the

perspective of a node along the label switched path, is that traffic

belonging to the LSP tunnel is identified solely on the basis of

packets arriving from the PHOP or "previous hop" (see [1]) with the

particular label value(s) assigned by this node to upstream senders

to the session. In fact, the IPv4(v6) that appears in the object

name only denotes that the destination address is an IPv4(v6)

address. When we refer to these objects generically, we use the

qualifier LSP_TUNNEL.

In some applications it is useful to associate sets of LSP tunnels.

This can be useful during reroute operations or to spread a traffic

trunk over multiple paths. In the traffic engineering application

such sets are called traffic engineered tunnels (TE tunnels). To

enable the identification and association of such LSP tunnels, two

identifiers are carried. A tunnel ID is part of the SESSION object.

The SESSION object uniquely defines a traffic engineered tunnel. The

SENDER_TEMPLATE and FILTER_SPEC objects carry an LSP ID. The

SENDER_TEMPLATE (or FILTER_SPEC) object together with the SESSION

object uniquely identifies an LSP tunnel

2.2. Operation of LSP Tunnels

This section summarizes some of the features supported by RSVP as

extended by this document related to the operation of LSP tunnels.

These include: (1) the capability to establish LSP tunnels with or

without QoS requirements, (2) the capability to dynamically reroute

an established LSP tunnel, (3) the capability to observe the actual

route traversed by an established LSP tunnel, (4) the capability to

identify and diagnose LSP tunnels, (5) the capability to preempt an

established LSP tunnel under administrative policy control, and (6)

the capability to perform downstream-on-demand label allocation,

distribution, and binding. In the following paragraphs, these

features are briefly described. More detailed descriptions can be

found in subsequent sections of this document.

To create an LSP tunnel, the first MPLS node on the path -- that is,

the sender node with respect to the path -- creates an RSVP Path

message with a session type of LSP_TUNNEL_IPv4 or LSP_TUNNEL_IPv6 and

inserts a LABEL_REQUEST object into the Path message. The

LABEL_REQUEST object indicates that a label binding for this path is

requested and also provides an indication of the network layer

protocol that is to be carried over this path. The reason for this

is that the network layer protocol sent down an LSP cannot be assumed

to be IP and cannot be deduced from the L2 header, which simply

identifies the higher layer protocol as MPLS.

If the sender node has knowledge of a route that has high likelihood

of meeting the tunnel's QoS requirements, or that makes efficient use

of network resources, or that satisfies some policy criteria, the

node can decide to use the route for some or all of its sessions. To

do this, the sender node adds an EXPLICIT_ROUTE object to the RSVP

Path message. The EXPLICIT_ROUTE object specifies the route as a

sequence of abstract nodes.

If, after a session has been successfully established, the sender

node discovers a better route, the sender can dynamically reroute the

session by simply changing the EXPLICIT_ROUTE object. If problems

are encountered with an EXPLICIT_ROUTE object, either because it

causes a routing loop or because some intermediate routers do not

support it, the sender node is notified.

By adding a RECORD_ROUTE object to the Path message, the sender node

can receive information about the actual route that the LSP tunnel

traverses. The sender node can also use this object to request

notification from the network concerning changes to the routing path.

The RECORD_ROUTE object is analogous to a path vector, and hence can

be used for loop detection.

Finally, a SESSION_ATTRIBUTE object can be added to Path messages to

aid in session identification and diagnostics. Additional control

information, such as setup and hold priorities, resource affinities

(see [3]), and local-protection, are also included in this object.

Routers along the path may use the setup and hold priorities along

with SENDER_TSPEC and any POLICY_DATA objects contained in Path

messages as input to policy control. For instance, in the traffic

engineering application, it is very useful to use the Path message as

a means of verifying that bandwidth exists at a particular priority

along an entire path before preempting any lower priority

reservations. If a Path message is allowed to progress when there

are insufficient resources, then there is a danger that lower

priority reservations downstream of this point will unnecessarily be

preempted in a futile attempt to service this request.

When the EXPLICIT_ROUTE object (ERO) is present, the Path message is

forwarded towards its destination along a path specified by the ERO.

Each node along the path records the ERO in its path state block.

Nodes may also modify the ERO before forwarding the Path message. In

this case the modified ERO SHOULD be stored in the path state block

in addition to the received ERO.

The LABEL_REQUEST object requests intermediate routers and receiver

nodes to provide a label binding for the session. If a node is

incapable of providing a label binding, it sends a PathErr message

with an "unknown object class" error. If the LABEL_REQUEST object is

not supported end to end, the sender node will be notified by the

first node which does not provide this support.

The destination node of a label-switched path responds to a

LABEL_REQUEST by including a LABEL object in its response RSVP Resv

message. The LABEL object is inserted in the filter spec list

immediately following the filter spec to which it pertains.

The Resv message is sent back upstream towards the sender, following

the path state created by the Path message, in reverse order. Note

that if the path state was created by use of an ERO, then the Resv

message will follow the reverse path of the ERO.

Each node that receives a Resv message containing a LABEL object uses

that label for outgoing traffic associated with this LSP tunnel. If

the node is not the sender, it allocates a new label and places that

label in the corresponding LABEL object of the Resv message which it

sends upstream to the PHOP. The label sent upstream in the LABEL

object is the label which this node will use to identify incoming

traffic associated with this LSP tunnel. This label also serves as

shorthand for the Filter Spec. The node can now update its "Incoming

Label Map" (ILM), which is used to map incoming labeled packets to a

"Next Hop Label Forwarding Entry" (NHLFE), see [2].

When the Resv message propagates upstream to the sender node, a

label-switched path is effectively established.

2.3. Service Classes

This document does not restrict the type of Integrated Service

requests for reservations. However, an implementation SHOULD support

the Controlled-Load service [4] and the Null Service [16].

2.4. Reservation Styles

The receiver node can select from among a set of possible reservation

styles for each session, and each RSVP session must have a particular

style. Senders have no influence on the choice of reservation style.

The receiver can choose different reservation styles for different

LSPs.

An RSVP session can result in one or more LSPs, depending on the

reservation style chosen.

Some reservation styles, such as FF, dedicate a particular

reservation to an individual sender node. Other reservation styles,

such as WF and SE, can share a reservation among several sender

nodes. The following sections discuss the different reservation

styles and their advantages and disadvantages. A more detailed

discussion of reservation styles can be found in [1].

2.4.1. Fixed Filter (FF) Style

The Fixed Filter (FF) reservation style creates a distinct

reservation for traffic from each sender that is not shared by other

senders. This style is common for applications in which traffic from

each sender is likely to be concurrent and independent. The total

amount of reserved bandwidth on a link for sessions using FF is the

sum of the reservations for the individual senders.

Because each sender has its own reservation, a unique label is

assigned to each sender. This can result in a point-to-point LSP

between every sender/receiver pair.

2.4.2. Wildcard Filter (WF) Style

With the Wildcard Filter (WF) reservation style, a single shared

reservation is used for all senders to a session. The total

reservation on a link remains the same regardless of the number of

senders.

A single multipoint-to-point label-switched-path is created for all

senders to the session. On links that senders to the session share,

a single label value is allocated to the session. If there is only

one sender, the LSP looks like a normal point-to-point connection.

When multiple senders are present, a multipoint-to-point LSP (a

reversed tree) is created.

This style is useful for applications in which not all senders send

traffic at the same time. A phone conference, for example, is an

application where not all speakers talk at the same time. If,

however, all senders send simultaneously, then there is no means of

getting the proper reservations made. Either the reserved bandwidth

on links close to the destination will be less than what is required

or then the reserved bandwidth on links close to some senders will be

greater than what is required. This restricts the applicability of

WF for traffic engineering purposes.

Furthermore, because of the merging rules of WF, EXPLICIT_ROUTE

objects cannot be used with WF reservations. As a result of this

issue and the lack of applicability to traffic engineering, use of WF

is not considered in this document.

2.4.3. Shared Explicit (SE) Style

The Shared Explicit (SE) style allows a receiver to explicitly

specify the senders to be included in a reservation. There is a

single reservation on a link for all the senders listed. Because

each sender is explicitly listed in the Resv message, different

labels may be assigned to different senders, thereby creating

separate LSPs.

SE style reservations can be provided using multipoint-to-point

label-switched-path or LSP per sender. Multipoint-to-point LSPs may

be used when path messages do not carry the EXPLICIT_ROUTE object, or

when Path messages have identical EXPLICIT_ROUTE objects. In either

of these cases a common label may be assigned.

Path messages from different senders can each carry their own ERO,

and the paths taken by the senders can converge and diverge at any

point in the network topology. When Path messages have differing

EXPLICIT_ROUTE objects, separate LSPs for each EXPLICIT_ROUTE object

must be established.

2.5. Rerouting Traffic Engineered Tunnels

One of the requirements for Traffic Engineering is the capability to

reroute an established TE tunnel under a number of conditions, based

on administrative policy. For example, in some contexts, an

administrative policy may dictate that a given TE tunnel is to be

rerouted when a more "optimal" route becomes available. Another

important context when TE tunnel reroute is usually required is upon

failure of a resource along the TE tunnel's established path. Under

some policies, it may also be necessary to return the TE tunnel to

its original path when the failed resource becomes re-activated.

In general, it is highly desirable not to disrupt traffic, or

adversely impact network operations while TE tunnel rerouting is in

progress. This adaptive and smooth rerouting requirement

necessitates establishing a new LSP tunnel and transferring traffic

from the old LSP tunnel onto it before tearing down the old LSP

tunnel. This concept is called "make-before-break." A problem can

arise because the old and new LSP tunnels might compete with each

other for resources on network segments which they have in common.

Depending on availability of resources, this competition can cause

Admission Control to prevent the new LSP tunnel from being

established. An advantage of using RSVP to establish LSP tunnels is

that it solves this problem very elegantly.

To support make-before-break in a smooth fashion, it is necessary

that on links that are common to the old and new LSPs, resources used

by the old LSP tunnel should not be released before traffic is

transitioned to the new LSP tunnel, and reservations should not be

counted twice because this might cause Admission Control to reject

the new LSP tunnel.

A similar situation can arise when one wants to increase the

bandwidth of a TE tunnel. The new reservation will be for the full

amount needed, but the actual allocation needed is only the delta

between the new and old bandwidth. If policy is being applied to

PATH messages by intermediate nodes, then a PATH message requesting

too much bandwidth will be rejected. In this situation simply

increasing the bandwidth request without changing the

SENDER_TEMPLATE, could result in a tunnel being torn down, depending

upon local policy.

The combination of the LSP_TUNNEL SESSION object and the SE

reservation style naturally accommodates smooth transitions in

bandwidth and routing. The idea is that the old and new LSP tunnels

share resources along links which they have in common. The

LSP_TUNNEL SESSION object is used to narrow the scope of the RSVP

session to the particular TE tunnel in question. To uniquely

identify a TE tunnel, we use the combination of the destination IP

address (an address of the node which is the egress of the tunnel), a

Tunnel ID, and the tunnel ingress node's IP address, which is placed

in the Extended Tunnel ID field.

During the reroute or bandwidth-increase operation, the tunnel

ingress needs to appear as two different senders to the RSVP session.

This is achieved by the inclusion of the "LSP ID", which is carried

in the SENDER_TEMPLATE and FILTER_SPEC objects. Since the semantics

of these objects are changed, a new C-Types are assigned.

To effect a reroute, the ingress node picks a new LSP ID and forms a

new SENDER_TEMPLATE. The ingress node then creates a new ERO to

define the new path. Thereafter the node sends a new Path Message

using the original SESSION object and the new SENDER_TEMPLATE and

ERO. It continues to use the old LSP and refresh the old Path

message. On links that are not held in common, the new Path message

is treated as a conventional new LSP tunnel setup. On links held in

common, the shared SESSION object and SE style allow the LSP to be

established sharing resources with the old LSP. Once the ingress

node receives a Resv message for the new LSP, it can transition

traffic to it and tear down the old LSP.

To effect a bandwidth-increase, a new Path Message with a new LSP_ID

can be used to attempt a larger bandwidth reservation while the

current LSP_ID continues to be refreshed to ensure that the

reservation is not lost if the larger reservation fails.

2.6. Path MTU

Standard RSVP [1] and Int-Serv [11] provide the RSVP sender with the

minimum MTU available between the sender and the receiver. This path

MTU identification capability is also provided for LSPs established

via RSVP.

Path MTU information is carried, depending on which is present, in

the Integrated Services or Null Service objects. When using

Integrated Services objects, path MTU is provided based on the

procedures defined in [11]. Path MTU identification when using Null

Service objects is defined in [16].

With standard RSVP, the path MTU information is used by the sender to

check which IP packets exceed the path MTU. For packets that exceed

the path MTU, the sender either fragments the packets or, when the IP

datagram has the "Don't Fragment" bit set, issues an ICMP destination

unreachable message. This path MTU related handling is also required

for LSPs established via RSVP.

The following algorithm applies to all unlabeled IP datagrams and to

any labeled packets which the node knows to be IP datagrams, to which

labels need to be added before forwarding. For labeled packets the

bottom of stack is found, the IP header examined.

Using the terminology defined in [5], an LSR MUST execute the

following algorithm:

1. Let N be the number of bytes in the label stack (i.e, 4 times the

number of label stack entries) including labels to be added by

this node.

2. Let M be the smaller of the "Maximum Initially Labeled IP Datagram

Size" or of (Path MTU - N).

When the size of an IPv4 datagram (without labels) exceeds the value

of M,

If the DF bit is not set in the IPv4 header, then

(a) the datagram MUST be broken into fragments, each of whose

size is no greater than M, and

(b) each fragment MUST be labeled and then forwarded.

If the DF bit is set in the IPv4 header, then

(a) the datagram MUST NOT be forwarded

(b) Create an ICMP Destination Unreachable Message:

i. set its Code field [12] to "Fragmentation Required and

DF Set",

ii. set its Next-Hop MTU field [13] to M

Message to the source of the of the discarded datagram.

When the size of an IPv6 datagram (without labels) exceeds the

value of M,

(a) the datagram MUST NOT be forwarded

(b) Create an ICMP Packet too Big Message with the Next-Hop

link MTU field [14] set to M

the source of the of the discarded datagram.

3. LSP Tunnel related Message Formats

Five new objects are defined in this section:

Object name Applicable RSVP messages

--------------- ------------------------

LABEL_REQUEST Path

LABEL Resv

EXPLICIT_ROUTE Path

RECORD_ROUTE Path, Resv

SESSION_ATTRIBUTE Path

New C-Types are also assigned for the SESSION, SENDER_TEMPLATE, and

FILTER_SPEC, objects.

Detailed descriptions of the new objects are given in later sections.

All new objects are OPTIONAL with respect to RSVP. An implementation

can choose to support a subset of objects. However, the

LABEL_REQUEST and LABEL objects are mandatory with respect to this

specification.

The LABEL and RECORD_ROUTE objects, are sender specific. In Resv

messages they MUST appear after the associated FILTER_SPEC and prior

to any subsequent FILTER_SPEC.

The relative placement of EXPLICIT_ROUTE, LABEL_REQUEST, and

SESSION_ATTRIBUTE objects is simply a recommendation. The ordering

of these objects is not important, so an implementation MUST be

prepared to accept objects in any order.

3.1. Path Message

The format of the Path message is as follows:

<Path Message> ::= <Common Header> [ <INTEGRITY> ]

<TIME_VALUES>

[ <EXPLICIT_ROUTE> ]

<LABEL_REQUEST>

[ <SESSION_ATTRIBUTE> ]

[ <POLICY_DATA> ... ]

[ <ADSPEC> ]

[ <RECORD_ROUTE> ]

3.2. Resv Message

The format of the Resv message is as follows:

<Resv Message> ::= <Common Header> [ <INTEGRITY> ]

<TIME_VALUES>

[ <RESV_CONFIRM> ] [ <SCOPE> ]

[ <POLICY_DATA> ... ]

<LABEL> [ <RECORD_ROUTE> ]

[ <RECORD_ROUTE> ]

<SE filter spec> ::= <FILTER_SPEC> <LABEL> [ <RECORD_ROUTE> ]

Note: LABEL and RECORD_ROUTE (if present), are bound to the

preceding FILTER_SPEC. No more than one LABEL and/or

RECORD_ROUTE may follow each FILTER_SPEC.

4. LSP Tunnel related Objects

4.1. Label Object

Labels MAY be carried in Resv messages. For the FF and SE styles, a

label is associated with each sender. The label for a sender MUST

immediately follow the FILTER_SPEC for that sender in the Resv

message.

The LABEL object has the following format:

LABEL class = 16, C_Type = 1

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

(top label)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The contents of a LABEL is a single label, encoded in 4 octets. Each

generic MPLS label is an unsigned integer in the range 0 through

1048575. Generic MPLS labels and FR labels are encoded right aligned

in 4 octets. ATM labels are encoded with the VPI right justified in

bits 0-15 and the VCI right justified in bits 16-31.

4.1.1. Handling Label Objects in Resv messages

In MPLS a node may support multiple label spaces, perhaps associating

a unique space with each incoming interface. For the purposes of the

following discussion, the term "same label" means the identical label

value drawn from the identical label space. Further, the following

applies only to unicast sessions.

Labels received in Resv messages on different interfaces are always

considered to be different even if the label value is the same.

4.1.1.1. Downstream

The downstream node selects a label to represent the flow. If a

label range has been specified in the label request, the label MUST

be drawn from that range. If no label is available the node sends a

PathErr message with an error code of "routing problem" and an error

value of "label allocation failure".

If a node receives a Resv message that has assigned the same label

value to multiple senders, then that node MAY also assign a single

value to those same senders or to any subset of those senders. Note

that if a node intends to police individual senders to a session, it

MUST assign unique labels to those senders.

In the case of ATM, one further condition applies. Some ATM nodes

are not capable of merging streams. These nodes MAY indicate this by

setting a bit in the label request to zero. The M-bit in the

LABEL_REQUEST object of C-Type 2, label request with ATM label range,

serves this purpose. The M-bit SHOULD be set by nodes which are

merge capable. If for any senders the M-bit is not set, the

downstream node MUST assign unique labels to those senders.

Once a label is allocated, the node formats a new LABEL object. The

node then sends the new LABEL object as part of the Resv message to

the previous hop. The node SHOULD be prepared to forward packets

carrying the assigned label prior to sending the Resv message. The

LABEL object SHOULD be kept in the Reservation State Block. It is

then used in the next Resv refresh event for formatting the Resv

message.

A node is expected to send a Resv message before its refresh timers

expire if the contents of the LABEL object change.

4.1.1.2. Upstream

A node uses the label carried in the LABEL object as the outgoing

label associated with the sender. The router allocates a new label

and binds it to the incoming interface of this session/sender. This

is the same interface that the router uses to forward Resv messages

to the previous hops.

Several circumstance can lead to an unacceptable label.

1. the node is a merge incapable ATM switch but the downstream

node has assigned the same label to two senders

2. The implicit null label was assigned, but the node is not

capable of doing a penultimate pop for the associated L3PID

3. The assigned label is outside the requested label range

In any of these events the node send a ResvErr message with an error

code of "routing problem" and an error value of "unacceptable label

value".

4.1.2. Non-support of the Label Object

Under normal circumstances, a node should never receive a LABEL

object in a Resv message unless it had included a LABEL_REQUEST

object in the corresponding Path message. However, an RSVP router

that does not recognize the LABEL object sends a ResvErr with the

error code "Unknown object class" toward the receiver. This causes

the reservation to fail.

4.2. Label Request Object

The Label Request Class is 19. Currently there are three possible

C_Types. Type 1 is a Label Request without label range. Type 2 is a

label request with an ATM label range. Type 3 is a label request

with a Frame Relay label range. The LABEL_REQUEST object formats are

shown below.

4.2.1. Label Request without Label Range

Class = 19, C_Type = 1

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Reserved L3PID

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Reserved

This field is reserved. It MUST be set to zero on transmission

and MUST be ignored on receipt.

L3PID

an identifier of the layer 3 protocol using this path.

Standard Ethertype values are used.

4.2.2. Label Request with ATM Label Range

Class = 19, C_Type = 2

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Reserved L3PID

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

M Res Minimum VPI Minimum VCI

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Res Maximum VPI Maximum VCI

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Reserved (Res)

This field is reserved. It MUST be set to zero on transmission

and MUST be ignored on receipt.

L3PID

an identifier of the layer 3 protocol using this path.

Standard Ethertype values are used.

Setting this bit to one indicates that the node is capable of

merging in the data plane

Minimum VPI (12 bits)

This 12 bit field specifies the lower bound of a block of

Virtual Path Identifiers that is supported on the originating

switch. If the VPI is less than 12-bits it MUST be right

justified in this field and preceding bits MUST be set to zero.

Minimum VCI (16 bits)

This 16 bit field specifies the lower bound of a block of

Virtual Connection Identifiers that is supported on the

originating switch. If the VCI is less than 16-bits it MUST be

right justified in this field and preceding bits MUST be set to

zero.

Maximum VPI (12 bits)

This 12 bit field specifies the upper bound of a block of

Virtual Path Identifiers that is supported on the originating

switch. If the VPI is less than 12-bits it MUST be right

justified in this field and preceding bits MUST be set to zero.

Maximum VCI (16 bits)

This 16 bit field specifies the upper bound of a block of

Virtual Connection Identifiers that is supported on the

originating switch. If the VCI is less than 16-bits it MUST be

right justified in this field and preceding bits MUST be set to

zero.

4.2.3. Label Request with Frame Relay Label Range

Class = 19, C_Type = 3

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Reserved L3PID

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Reserved DLI Minimum DLCI

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Reserved Maximum DLCI

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Reserved

This field is reserved. It MUST be set to zero on transmission

and ignored on receipt.

L3PID

an identifier of the layer 3 protocol using this path.

Standard Ethertype values are used.

DLI

DLCI Length Indicator. The number of bits in the DLCI. The

following values are supported:

Len DLCI bits

0 10

2 23

Minimum DLCI

This 23-bit field specifies the lower bound of a block of Data

Link Connection Identifiers (DLCIs) that is supported on the

originating switch. The DLCI MUST be right justified in this

field and unused bits MUST be set to 0.

Maximum DLCI

This 23-bit field specifies the upper bound of a block of Data

Link Connection Identifiers (DLCIs) that is supported on the

originating switch. The DLCI MUST be right justified in this

field and unused bits MUST be set to 0.

4.2.4. Handling of LABEL_REQUEST

To establish an LSP tunnel the sender creates a Path message with a

LABEL_REQUEST object. The LABEL_REQUEST object indicates that a

label binding for this path is requested and provides an indication

of the network layer protocol that is to be carried over this path.

This permits non-IP network layer protocols to be sent down an LSP.

This information can also be useful in actual label allocation,

because some reserved labels are protocol specific, see [5].

The LABEL_REQUEST SHOULD be stored in the Path State Block, so that

Path refresh messages will also contain the LABEL_REQUEST object.

When the Path message reaches the receiver, the presence of the

LABEL_REQUEST object triggers the receiver to allocate a label and to

place the label in the LABEL object for the corresponding Resv

message. If a label range was specified, the label MUST be allocated

from that range. A receiver that accepts a LABEL_REQUEST object MUST

include a LABEL object in Resv messages pertaining to that Path

message. If a LABEL_REQUEST object was not present in the Path

message, a node MUST NOT include a LABEL object in a Resv message for

that Path message's session and PHOP.

A node that sends a LABEL_REQUEST object MUST be ready to accept and

correctly process a LABEL object in the corresponding Resv messages.

A node that recognizes a LABEL_REQUEST object, but that is unable to

support it (possibly because of a failure to allocate labels) SHOULD

send a PathErr with the error code "Routing problem" and the error

value "MPLS label allocation failure." This includes the case where

a label range has been specified and a label cannot be allocated from

that range.

A node which receives and forwards a Path message each with a

LABEL_REQUEST object, MUST copy the L3PID from the received

LABEL_REQUEST object to the forwarded LABEL_REQUEST object.

If the receiver cannot support the protocol L3PID, it SHOULD send a

PathErr with the error code "Routing problem" and the error value

"Unsupported L3PID." This causes the RSVP session to fail.

4.2.5. Non-support of the Label Request Object

An RSVP router that does not recognize the LABEL_REQUEST object sends

a PathErr with the error code "Unknown object class" toward the

sender. An RSVP router that recognizes the LABEL_REQUEST object but

does not recognize the C_Type sends a PathErr with the error code

"Unknown object C_Type" toward the sender. This causes the path

setup to fail. The sender should notify management that a LSP cannot

be established and possibly take action to continue the reservation

without the LABEL_REQUEST.

RSVP is designed to cope gracefully with non-RSVP routers anywhere

between senders and receivers. However, obviously, non-RSVP routers

cannot convey labels via RSVP. This means that if a router has a

neighbor that is known to not be RSVP capable, the router MUST NOT

advertise the LABEL_REQUEST object when sending messages that pass

through the non-RSVP routers. The router SHOULD send a PathErr back

to the sender, with the error code "Routing problem" and the error

value "MPLS being negotiated, but a non-RSVP capable router stands in

the path." This same message SHOULD be sent, if a router receives a

LABEL_REQUEST object in a message from a non-RSVP capable router.

See [1] for a description of how a downstream router can determine

the presence of non-RSVP routers.

4.3. Explicit Route Object

Explicit routes are specified via the EXPLICIT_ROUTE object (ERO).

The Explicit Route Class is 20. Currently one C_Type is defined,

Type 1 Explicit Route. The EXPLICIT_ROUTE object has the following

format:

Class = 20, C_Type = 1

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

// (Subobjects) //

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Subobjects

The contents of an EXPLICIT_ROUTE object are a series of variable-

length data items called subobjects. The subobjects are defined in

section 4.3.3 below.

If a Path message contains multiple EXPLICIT_ROUTE objects, only the

first object is meaningful. Subsequent EXPLICIT_ROUTE objects MAY be

ignored and SHOULD NOT be propagated.

4.3.1. Applicability

The EXPLICIT_ROUTE object is intended to be used only for unicast

situations. Applications of explicit routing to multicast are a

topic for further research.

The EXPLICIT_ROUTE object is to be used only when all routers along

the explicit route support RSVP and the EXPLICIT_ROUTE object. The

EXPLICIT_ROUTE object is assigned a class value of the form 0bbbbbbb.

RSVP routers that do not support the object will therefore respond

with an "Unknown Object Class" error.

4.3.2. Semantics of the Explicit Route Object

An explicit route is a particular path in the network topology.

Typically, the explicit route is determined by a node, with the

intent of directing traffic along that path.

An explicit route is described as a list of groups of nodes along the

explicit route. In addition to the ability to identify specific

nodes along the path, an explicit route can identify a group of nodes

that must be traversed along the path. This capability allows the

routing system a significant amount of local flexibility in

fulfilling a request for an explicit route. This capability allows

the generator of the explicit route to have imperfect information

about the details of the path.

The explicit route is encoded as a series of subobjects contained in

an EXPLICIT_ROUTE object. Each subobject identifies a group of nodes

in the explicit route. An explicit route is thus a specification of

groups of nodes to be traversed.

To formalize the discussion, we call each group of nodes an abstract

node. Thus, we say that an explicit route is a specification of a

set of abstract nodes to be traversed. If an abstract node consists

of only one node, we refer to it as a simple abstract node.

As an example of the concept of abstract nodes, consider an explicit

route that consists solely of Autonomous System number subobjects.

Each subobject corresponds to an Autonomous System in the global

topology. In this case, each Autonomous System is an abstract node,

and the explicit route is a path that includes each of the specified

Autonomous Systems. There may be multiple hops within each

Autonomous System, but these are opaque to the source node for the

explicit route.

4.3.3. Subobjects

The contents of an EXPLICIT_ROUTE object are a series of variable-

length data items called subobjects. Each subobject has the form:

0 1

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------//----------------+

L Type Length (Subobject contents)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------//----------------+

The L bit is an attribute of the subobject. The L bit is set

if the subobject represents a loose hop in the explicit route.

If the bit is not set, the subobject represents a strict hop in

the explicit route.

Type

The Type indicates the type of contents of the subobject.

Currently defined values are:

1 IPv4 prefix

2 IPv6 prefix

32 Autonomous system number

Length

The Length contains the total length of the subobject in bytes,

including the L, Type and Length fields. The Length MUST be at

least 4, and MUST be a multiple of 4.

4.3.3.1. Strict and Loose Subobjects

The L bit in the subobject is a one-bit attribute. If the L bit is

set, then the value of the attribute is 'loose.' Otherwise, the

value of the attribute is 'strict.' For brevity, we say that if the

value of the subobject attribute is 'loose' then it is a 'loose

subobject.' Otherwise, it's a 'strict subobject.' Further, we say

that the abstract node of a strict or loose subobject is a strict or

a loose node, respectively. Loose and strict nodes are always

interpreted relative to their prior abstract nodes.

The path between a strict node and its preceding node MUST include

only network nodes from the strict node and its preceding abstract

node.

The path between a loose node and its preceding node MAY include

other network nodes that are not part of the strict node or its

preceding abstract node.

4.3.3.2. Subobject 1: IPv4 prefix

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

L Type Length IPv4 address (4 bytes)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv4 address (continued) Prefix Length Resvd

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The L bit is an attribute of the subobject. The L bit is set

if the subobject represents a loose hop in the explicit route.

If the bit is not set, the subobject represents a strict hop in

the explicit route.

Type

0x01 IPv4 address

Length

The Length contains the total length of the subobject in bytes,

including the Type and Length fields. The Length is always 8.

IPv4 address

An IPv4 address. This address is treated as a prefix based on

the prefix length value below. Bits beyond the prefix are

ignored on receipt and SHOULD be set to zero on transmission.

Prefix length

Length in bits of the IPv4 prefix

Padding

Zero on transmission. Ignored on receipt.

The contents of an IPv4 prefix subobject are a 4-octet IPv4 address,

a 1-octet prefix length, and a 1-octet pad. The abstract node

represented by this subobject is the set of nodes that have an IP

address which lies within this prefix. Note that a prefix length of

32 indicates a single IPv4 node.

4.3.3.3. Subobject 2: IPv6 Prefix

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

L Type Length IPv6 address (16 bytes)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv6 address (continued)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv6 address (continued)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv6 address (continued)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv6 address (continued) Prefix Length Resvd

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The L bit is an attribute of the subobject. The L bit is set

if the subobject represents a loose hop in the explicit route.

If the bit is not set, the subobject represents a strict hop in

the explicit route.

Type

0x02 IPv6 address

Length

The Length contains the total length of the subobject in bytes,

including the Type and Length fields. The Length is always 20.

IPv6 address

An IPv6 address. This address is treated as a prefix based on

the prefix length value below. Bits beyond the prefix are

ignored on receipt and SHOULD be set to zero on transmission.

Prefix Length

Length in bits of the IPv6 prefix.

Padding

Zero on transmission. Ignored on receipt.

The contents of an IPv6 prefix subobject are a 16-octet IPv6 address,

a 1-octet prefix length, and a 1-octet pad. The abstract node

represented by this subobject is the set of nodes that have an IP

address which lies within this prefix. Note that a prefix length of

128 indicates a single IPv6 node.

4.3.3.4. Subobject 32: Autonomous System Number

The contents of an Autonomous System (AS) number subobject are a 2-

octet AS number. The abstract node represented by this subobject is

the set of nodes belonging to the autonomous system.

The length of the AS number subobject is 4 octets.

4.3.4. Processing of the Explicit Route Object

4.3.4.1. Selection of the Next Hop

A node receiving a Path message containing an EXPLICIT_ROUTE object

must determine the next hop for this path. This is necessary because

the next abstract node along the explicit route might be an IP subnet

or an Autonomous System. Therefore, selection of this next hop may

involve a decision from a set of feasible alternatives. The criteria

used to make a selection from feasible alternatives is implementation

dependent and can also be impacted by local policy, and is beyond the

scope of this specification. However, it is assumed that each node

will make a best effort attempt to determine a loop-free path. Note

that paths so determined can be overridden by local policy.

To determine the next hop for the path, a node performs the following

steps:

1) The node receiving the RSVP message MUST first evaluate the first

subobject. If the node is not part of the abstract node described

by the first subobject, it has received the message in error and

SHOULD return a "Bad initial subobject" error. If there is no

first subobject, the message is also in error and the system

SHOULD return a "Bad EXPLICIT_ROUTE object" error.

2) If there is no second subobject, this indicates the end of the

explicit route. The EXPLICIT_ROUTE object SHOULD be removed from

the Path message. This node may or may not be the end of the

path. Processing continues with section 4.3.4.2, where a new

EXPLICIT_ROUTE object MAY be added to the Path message.

3) Next, the node evaluates the second subobject. If the node is

also a part of the abstract node described by the second

subobject, then the node deletes the first subobject and continues

processing with step 2, above. Note that this makes the second

subobject into the first subobject of the next iteration and

allows the node to identify the next abstract node on the path of

the message after possible repeated application(s) of steps 2 and

4) Abstract Node Border Case: The node determines whether it is

topologically adjacent to the abstract node described by the

second subobject. If so, the node selects a particular next hop

which is a member of the abstract node. The node then deletes the

first subobject and continues processing with section 4.3.4.2.

5) Interior of the Abstract Node Case: Otherwise, the node selects a

next hop within the abstract node of the first subobject (which

the node belongs to) that is along the path to the abstract node

of the second subobject (which is the next abstract node). If no

such path exists then there are two cases:

5a) If the second subobject is a strict subobject, there is an error

and the node SHOULD return a "Bad strict node" error.

5b) Otherwise, if the second subobject is a loose subobject, the node

selects any next hop that is along the path to the next abstract

node. If no path exists, there is an error, and the node SHOULD

return a "Bad loose node" error.

6) Finally, the node replaces the first subobject with any subobject

that denotes an abstract node containing the next hop. This is

necessary so that when the explicit route is received by the next

hop, it will be accepted.

4.3.4.2. Adding subobjects to the Explicit Route Object

After selecting a next hop, the node MAY alter the explicit route in

the following ways.

If, as part of executing the algorithm in section 4.3.4.1, the

EXPLICIT_ROUTE object is removed, the node MAY add a new

EXPLICIT_ROUTE object.

Otherwise, if the node is a member of the abstract node for the first

subobject, a series of subobjects MAY be inserted before the first

subobject or MAY replace the first subobject. Each subobject in this

series MUST denote an abstract node that is a subset of the current

abstract node.

Alternately, if the first subobject is a loose subobject, an

arbitrary series of subobjects MAY be inserted prior to the first

subobject.

4.3.5. Loops

While the EXPLICIT_ROUTE object is of finite length, the existence of

loose nodes implies that it is possible to construct forwarding loops

during transients in the underlying routing protocol. This can be

detected by the originator of the explicit route through the use of

another opaque route object called the RECORD_ROUTE object. The

RECORD_ROUTE object is used to collect detailed path information and

is useful for loop detection and for diagnostics.

4.3.6. Forward Compatibility

It is anticipated that new subobjects may be defined over time. A

node which encounters an unrecognized subobject during its normal ERO

processing sends a PathErr with the error code "Routing Error" and

error value of "Bad Explicit Route Object" toward the sender. The

EXPLICIT_ROUTE object is included, truncated (on the left) to the

offending subobject. The presence of an unrecognized subobject which

is not encountered in a node's ERO processing SHOULD be ignored. It

is passed forward along with the rest of the remaining ERO stack.

4.3.7. Non-support of the Explicit Route Object

An RSVP router that does not recognize the EXPLICIT_ROUTE object

sends a PathErr with the error code "Unknown object class" toward the

sender. This causes the path setup to fail. The sender should

notify management that a LSP cannot be established and possibly take

action to continue the reservation without the EXPLICIT_ROUTE or via

a different explicit route.

4.4. Record Route Object

Routes can be recorded via the RECORD_ROUTE object (RRO).

Optionally, labels may also be recorded. The Record Route Class is

21. Currently one C_Type is defined, Type 1 Record Route. The

RECORD_ROUTE object has the following format:

Class = 21, C_Type = 1

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

// (Subobjects) //

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Subobjects

The contents of a RECORD_ROUTE object are a series of

variable-length data items called subobjects. The subobjects

are defined in section 4.4.1 below.

The RRO can be present in both RSVP Path and Resv messages. If a

Path message contains multiple RROs, only the first RRO is

meaningful. Subsequent RROs SHOULD be ignored and SHOULD NOT be

propagated. Similarly, if in a Resv message multiple RROs are

encountered following a FILTER_SPEC before another FILTER_SPEC is

encountered, only the first RRO is meaningful. Subsequent RROs

SHOULD be ignored and SHOULD NOT be propagated.

4.4.1. Subobjects

The contents of a RECORD_ROUTE object are a series of variable-length

data items called subobjects. Each subobject has its own Length

field. The length contains the total length of the subobject in

bytes, including the Type and Length fields. The length MUST always

be a multiple of 4, and at least 4.

Subobjects are organized as a last-in-first-out stack. The first

subobject relative to the beginning of RRO is considered the top.

The last subobject is considered the bottom. When a new subobject is

added, it is always added to the top.

An empty RRO with no subobjects is considered illegal.

Three kinds of subobjects are currently defined.

4.4.1.1. Subobject 1: IPv4 address

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type Length IPv4 address (4 bytes)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv4 address (continued) Prefix Length Flags

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type

0x01 IPv4 address

Length

The Length contains the total length of the subobject in bytes,

including the Type and Length fields. The Length is always 8.

IPv4 address

A 32-bit unicast, host address. Any network-reachable

interface address is allowed here. Illegal addresses, such as

certain loopback addresses, SHOULD NOT be used.

Prefix length

Flags

0x01 Local protection available

Indicates that the link downstream of this node is

protected via a local repair mechanism. This flag can

only be set if the Local protection flag was set in the

SESSION_ATTRIBUTE object of the corresponding Path

message.

0x02 Local protection in use

Indicates that a local repair mechanism is in use to

maintain this tunnel (usually in the face of an outage

of the link it was previously routed over).

4.4.1.2. Subobject 2: IPv6 address

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type Length IPv6 address (16 bytes)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv6 address (continued)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv6 address (continued)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv6 address (continued)

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv6 address (continued) Prefix Length Flags

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type

0x02 IPv6 address

Length

The Length contains the total length of the subobject in bytes,

including the Type and Length fields. The Length is always 20.

IPv6 address

A 128-bit unicast host address.

Prefix length

128

Flags

0x01 Local protection available

Indicates that the link downstream of this node is

protected via a local repair mechanism. This flag can

only be set if the Local protection flag was set in the

SESSION_ATTRIBUTE object of the corresponding Path

message.

0x02 Local protection in use

Indicates that a local repair mechanism is in use to

maintain this tunnel (usually in the face of an outage

of the link it was previously routed over).

4.4.1.3. Subobject 3, Label

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type Length Flags C-Type

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Contents of Label Object

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type

0x03 Label

Length

The Length contains the total length of the subobject in bytes,

including the Type and Length fields.

Flags

0x01 = Global label

This flag indicates that the label will be understood

if received on any interface.

C-Type

The C-Type of the included Label Object. Copied from the Label

Object.

Contents of Label Object

The contents of the Label Object. Copied from the Label Object

4.4.2. Applicability

Only the procedures for use in unicast sessions are defined here.

There are three possible uses of RRO in RSVP. First, an RRO can

function as a loop detection mechanism to discover L3 routing loops,

or loops inherent in the explicit route. The exact procedure for

doing so is described later in this document.

Second, an RRO collects up-to-date detailed path information hop-by-

hop about RSVP sessions, providing valuable information to the sender

or receiver. Any path change (due to network topology changes) will

be reported.

Third, RRO syntax is designed so that, with minor changes, the whole

object can be used as input to the EXPLICIT_ROUTE object. This is

useful if the sender receives RRO from the receiver in a Resv

message, applies it to EXPLICIT_ROUTE object in the next Path message

in order to "pin down session path".

4.4.3. Processing RRO

Typically, a node initiates an RSVP session by adding the RRO to the

Path message. The initial RRO contains only one subobject - the

sender's IP addresses. If the node also desires label recording, it

sets the Label_Recording flag in the SESSION_ATTRIBUTE object.

When a Path message containing an RRO is received by an intermediate

router, the router stores a copy of it in the Path State Block. The

RRO is then used in the next Path refresh event for formatting Path

messages. When a new Path message is to be sent, the router adds a

new subobject to the RRO and appends the resulting RRO to the Path

message before transmission.

The newly added subobject MUST be this router's IP address. The

address to be added SHOULD be the interface address of the outgoing

Path messages. If there are multiple addresses to choose from, the

decision is a local matter. However, it is RECOMMENDED that the same

address be chosen consistently.

When the Label_Recording flag is set in the SESSION_ATTRIBUTE object,

nodes doing route recording SHOULD include a Label Record subobject.

If the node is using a global label space, then it SHOULD set the

Global Label flag.

The Label Record subobject is pushed onto the RECORD_ROUTE object

prior to pushing on the node's IP address. A node MUST NOT push on a

Label Record subobject without also pushing on an IPv4 or IPv6

subobject.

Note that on receipt of the initial Path message, a node is unlikely

to have a label to include. Once a label is oBTained, the node

SHOULD include the label in the RRO in the next Path refresh event.

If the newly added subobject causes the RRO to be too big to fit in a

Path (or Resv) message, the RRO object SHALL be dropped from the

message and message processing continues as normal. A PathErr (or

ResvErr) message SHOULD be sent back to the sender (or receiver). An

error code of "Notify" and an error value of "RRO too large for MTU"

is used. If the receiver receives such a ResvErr, it SHOULD send a

PathErr message with error code of "Notify" and an error value of

"RRO notification".

A sender receiving either of these error values SHOULD remove the RRO

from the Path message.

Nodes SHOULD resend the above PathErr or ResvErr message each n

seconds where n is the greater of 15 and the refresh interval for the

associated Path or RESV message. The node MAY apply limits and/or

back-off timers to limit the number of messages sent.

An RSVP router can decide to send Path messages before its refresh

time if the RRO in the next Path message is different from the

previous one. This can happen if the contents of the RRO received

from the previous hop router changes or if this RRO is newly added to

(or deleted from) the Path message.

When the destination node of an RSVP session receives a Path message

with an RRO, this indicates that the sender node needs route

recording. The destination node initiates the RRO process by adding

an RRO to Resv messages. The processing mirrors that of the Path

messages. The only difference is that the RRO in a Resv message

records the path information in the reverse direction.

Note that each node along the path will now have the complete route

from source to destination. The Path RRO will have the route from

the source to this node; the Resv RRO will have the route from this

node to the destination. This is useful for network management.

A received Path message without an RRO indicates that the sender node

no longer needs route recording. Subsequent Resv messages SHALL NOT

contain an RRO.

4.4.4. Loop Detection

As part of processing an incoming RRO, an intermediate router looks

into all subobjects contained within the RRO. If the router

determines that it is already in the list, a forwarding loop exists.

An RSVP session is loop-free if downstream nodes receive Path

messages or upstream nodes receive Resv messages with no routing

loops detected in the contained RRO.

There are two broad classifications of forwarding loops. The first

class is the transient loop, which occurs as a normal part of

operations as L3 routing tries to converge on a consistent forwarding

path for all destinations. The second class of forwarding loop is

the permanent loop, which normally results from network mis-

configuration.

The action performed by a node on receipt of an RRO depends on the

message type in which the RRO is received.

For Path messages containing a forwarding loop, the router builds and

sends a "Routing problem" PathErr message, with the error value "loop

detected," and drops the Path message. Until the loop is eliminated,

this session is not suitable for forwarding data packets. How the

loop eliminated is beyond the scope of this document.

For Resv messages containing a forwarding loop, the router simply

drops the message. Resv messages should not loop if Path messages do

not loop.

4.4.5. Forward Compatibility

New subobjects may be defined for the RRO. When processing an RRO,

unrecognized subobjects SHOULD be ignored and passed on. When

processing an RRO for loop detection, a node SHOULD parse over any

unrecognized objects. Loop detection works by detecting subobjects

which were inserted by the node itself on an earlier pass of the

object. This ensures that the subobjects necessary for loop

detection are always understood.

4.4.6. Non-support of RRO

The RRO object is to be used only when all routers along the path

support RSVP and the RRO object. The RRO object is assigned a class

value of the form 0bbbbbbb. RSVP routers that do not support the

object will therefore respond with an "Unknown Object Class" error.

4.5. Error Codes for ERO and RRO

In the processing described above, certain errors must be reported as

either a "Routing Problem" or "Notify". The value of the "Routing

Problem" error code is 24; the value of the "Notify" error code is

25.

The following defines error values for the Routing Problem Error

Code:

Value Error:

1 Bad EXPLICIT_ROUTE object

2 Bad strict node

3 Bad loose node

4 Bad initial subobject

5 No route available toward destination

6 Unacceptable label value

7 RRO indicated routing loops

8 MPLS being negotiated, but a non-RSVP-capable router

stands in the path

9 MPLS label allocation failure

10 Unsupported L3PID

For the Notify Error Code, the 16 bits of the Error Value field are:

ss00 cccc cccc cccc

The high order bits are as defined under Error Code 1. (See [1]).

When ss = 00, the following subcodes are defined:

1 RRO too large for MTU

2 RRO notification

3 Tunnel locally repaired

4.6. Session, Sender Template, and Filter Spec Objects

New C-Types are defined for the SESSION, SENDER_TEMPLATE and

FILTER_SPEC objects.

The LSP_TUNNEL objects have the following format:

4.6.1. Session Object

4.6.1.1. LSP_TUNNEL_IPv4 Session Object

Class = SESSION, LSP_TUNNEL_IPv4 C-Type = 7

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv4 tunnel end point address

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

MUST be zero Tunnel ID

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Extended Tunnel ID

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv4 tunnel end point address

IPv4 address of the egress node for the tunnel.

Tunnel ID

A 16-bit identifier used in the SESSION that remains constant

over the life of the tunnel.

Extended Tunnel ID

A 32-bit identifier used in the SESSION that remains constant

over the life of the tunnel. Normally set to all zeros.

Ingress nodes that wish to narrow the scope of a SESSION to the

ingress-egress pair may place their IPv4 address here as a

globally unique identifier.

4.6.1.2. LSP_TUNNEL_IPv6 Session Object

Class = SESSION, LSP_TUNNEL_IPv6 C_Type = 8

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

+ +

IPv6 tunnel end point address

+ +

(16 bytes)

+ +

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

MUST be zero Tunnel ID

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

+ +

Extended Tunnel ID

+ +

(16 bytes)

+ +

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv6 tunnel end point address

IPv6 address of the egress node for the tunnel.

Tunnel ID

A 16-bit identifier used in the SESSION that remains constant

over the life of the tunnel.

Extended Tunnel ID

A 16-byte identifier used in the SESSION that remains constant

over the life of the tunnel. Normally set to all zeros.

Ingress nodes that wish to narrow the scope of a SESSION to the

ingress-egress pair may place their IPv6 address here as a

globally unique identifier.

4.6.2. Sender Template Object

4.6.2.1. LSP_TUNNEL_IPv4 Sender Template Object

Class = SENDER_TEMPLATE, LSP_TUNNEL_IPv4 C-Type = 7

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv4 tunnel sender address

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

MUST be zero LSP ID

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv4 tunnel sender address

IPv4 address for a sender node

LSP ID

A 16-bit identifier used in the SENDER_TEMPLATE and the

FILTER_SPEC that can be changed to allow a sender to share

resources with itself.

4.6.2.2. LSP_TUNNEL_IPv6 Sender Template Object

Class = SENDER_TEMPLATE, LSP_TUNNEL_IPv6 C_Type = 8

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

+ +

IPv6 tunnel sender address

+ +

(16 bytes)

+ +

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

MUST be zero LSP ID

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv6 tunnel sender address

IPv6 address for a sender node

LSP ID

A 16-bit identifier used in the SENDER_TEMPLATE and the

FILTER_SPEC that can be changed to allow a sender to share

resources with itself.

4.6.3. Filter Specification Object

4.6.3.1. LSP_TUNNEL_IPv4 Filter Specification Object

Class = FILTER SPECIFICATION, LSP_TUNNEL_IPv4 C-Type = 7

The format of the LSP_TUNNEL_IPv4 FILTER_SPEC object is identical to

the LSP_TUNNEL_IPv4 SENDER_TEMPLATE object.

4.6.3.2. LSP_TUNNEL_IPv6 Filter Specification Object

Class = FILTER SPECIFICATION, LSP_TUNNEL_IPv6 C_Type = 8

The format of the LSP_TUNNEL_IPv6 FILTER_SPEC object is identical to

the LSP_TUNNEL_IPv6 SENDER_TEMPLATE object.

4.6.4. Reroute and Bandwidth Increase Procedure

This section describes how to setup a tunnel that is capable of

maintaining resource reservations (without double counting) while it

is being rerouted or while it is attempting to increase its

bandwidth. In the initial Path message, the ingress node forms a

SESSION object, assigns a Tunnel_ID, and places its IPv4 address in

the Extended_Tunnel_ID. It also forms a SENDER_TEMPLATE and assigns

a LSP_ID. Tunnel setup then proceeds according to the normal

procedure.

On receipt of the Path message, the egress node sends a Resv message

with the STYLE Shared Explicit toward the ingress node.

When an ingress node with an established path wants to change that

path, it forms a new Path message as follows. The existing SESSION

object is used. In particular the Tunnel_ID and Extended_Tunnel_ID

are unchanged. The ingress node picks a new LSP_ID to form a new

SENDER_TEMPLATE. It creates an EXPLICIT_ROUTE object for the new

route. The new Path message is sent. The ingress node refreshes

both the old and new path messages.

The egress node responds with a Resv message with an SE flow

descriptor formatted as:

<new_LABEL_OBJECT>

(Note that if the PHOPs are different, then two messages are sent

each with the appropriate FILTER_SPEC and LABEL_OBJECT.)

When the ingress node receives the Resv Message(s), it may begin

using the new route. It SHOULD send a PathTear message for the old

route.

4.7. Session Attribute Object

The Session Attribute Class is 207. Two C_Types are defined,

LSP_TUNNEL, C-Type = 7 and LSP_TUNNEL_RA, C-Type = 1. The

LSP_TUNNEL_RA C-Type includes all the same fields as the LSP_TUNNEL

C-Type. Additionally it carries resource affinity information. The

formats are as follows:

4.7.1. Format without resource affinities

SESSION_ATTRIBUTE class = 207, LSP_TUNNEL C-Type = 7

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Setup Prio Holding Prio Flags Name Length

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

// Session Name (NULL padded display string) //

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Setup Priority

The priority of the session with respect to taking resources,

in the range of 0 to 7. The value 0 is the highest priority.

The Setup Priority is used in deciding whether this session can

preempt another session.

Holding Priority

The priority of the session with respect to holding resources,

in the range of 0 to 7. The value 0 is the highest priority.

Holding Priority is used in deciding whether this session can

be preempted by another session.

Flags

0x01 Local protection desired

This flag permits transit routers to use a local repair

mechanism which may result in violation of the explicit

route object. When a fault is detected on an adjacent

downstream link or node, a transit router can reroute

traffic for fast service restoration.

0x02 Label recording desired

This flag indicates that label information should be

included when doing a route record.

0x04 SE Style desired

This flag indicates that the tunnel ingress node may

choose to reroute this tunnel without tearing it down.

A tunnel egress node SHOULD use the SE Style when

responding with a Resv message.

Name Length

The length of the display string before padding, in bytes.

Session Name

A null padded string of characters.

4.7.2. Format with resource affinities

SESSION_ATTRIBUTE class = 207, LSP_TUNNEL_RA C-Type = 1

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Exclude-any

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Include-any

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Include-all

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Setup Prio Holding Prio Flags Name Length

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

// Session Name (NULL padded display string) //

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Exclude-any

A 32-bit vector representing a set of attribute filters

associated with a tunnel any of which renders a link

unacceptable.

Include-any

A 32-bit vector representing a set of attribute filters

associated with a tunnel any of which renders a link acceptable

(with respect to this test). A null set (all bits set to zero)

automatically passes.

Include-all

A 32-bit vector representing a set of attribute filters

associated with a tunnel all of which must be present for a

link to be acceptable (with respect to this test). A null set

(all bits set to zero) automatically passes.

Setup Priority

The priority of the session with respect to taking resources,

in the range of 0 to 7. The value 0 is the highest priority.

The Setup Priority is used in deciding whether this session can

preempt another session.

Holding Priority

The priority of the session with respect to holding resources,

in the range of 0 to 7. The value 0 is the highest priority.

Holding Priority is used in deciding whether this session can

be preempted by another session.

Flags

0x01 Local protection desired

This flag permits transit routers to use a local repair

mechanism which may result in violation of the explicit

route object. When a fault is detected on an adjacent

downstream link or node, a transit router can reroute

traffic for fast service restoration.

0x02 Label recording desired

This flag indicates that label information should be

included when doing a route record.

0x04 SE Style desired

This flag indicates that the tunnel ingress node may

choose to reroute this tunnel without tearing it down.

A tunnel egress node SHOULD use the SE Style when

responding with a Resv message.

Name Length

The length of the display string before padding, in bytes.

Session Name

A null padded string of characters.

4.7.3. Procedures applying to both C-Types

The support of setup and holding priorities is OPTIONAL. A node can

recognize this information but be unable to perform the requested

operation. The node SHOULD pass the information downstream

unchanged.

As noted above, preemption is implemented by two priorities. The

Setup Priority is the priority for taking resources. The Holding

Priority is the priority for holding a resource. Specifically, the

Holding Priority is the priority at which resources assigned to this

session will be reserved. The Setup Priority SHOULD never be higher

than the Holding Priority for a given session.

The setup and holding priorities are directly analogous to the

preemption and defending priorities as defined in [9]. While the

interaction of these two objects is ultimately a matter of policy,

the following default interaction is RECOMMENDED.

When both objects are present, the preemption priority policy element

is used. A mapping between the priority spaces is defined as

follows. A session attribute priority S is mapped to a preemption

priority P by the formula P = 2^(14-2S). The reverse mapping is

shown in the following table.

Preemption Priority Session Attribute Priority

0 - 3 7

4 - 15 6

16 - 63 5

64 - 255 4

256 - 1023 3

1024 - 4095 2

4096 - 16383 1

16384 - 65535 0

When a new Path message is considered for admission, the bandwidth

requested is compared with the bandwidth available at the priority

specified in the Setup Priority.

If the requested bandwidth is not available a PathErr message is

returned with an Error Code of 01, Admission Control Failure, and an

Error Value of 0x0002. The first 0 in the Error Value indicates a

globally defined subcode and is not informational. The 002 indicates

"requested bandwidth unavailable".

If the requested bandwidth is less than the unused bandwidth then

processing is complete. If the requested bandwidth is available, but

is in use by lower priority sessions, then lower priority sessions

(beginning with the lowest priority) MAY be preempted to free the

necessary bandwidth.

When preemption is supported, each preempted reservation triggers a

TC_Preempt() upcall to local clients, passing a subcode that

indicates the reason. A ResvErr and/or PathErr with the code "Policy

Control failure" SHOULD be sent toward the downstream receivers and

upstream senders.

The support of local-protection is OPTIONAL. A node may recognize

the local-protection Flag but may be unable to perform the requested

operation. In this case, the node SHOULD pass the information

downstream unchanged.

The recording of the Label subobject in the ROUTE_RECORD object is

controlled by the label-recording-desired flag in the

SESSION_ATTRIBUTE object. Since the Label subobject is not needed

for all applications, it is not automatically recorded. The flag

allows applications to request this only when needed.

The contents of the Session Name field are a string, typically of

display-able characters. The Length MUST always be a multiple of 4

and MUST be at least 8. For an object length that is not a multiple

of 4, the object is padded with trailing NULL characters. The Name

Length field contains the actual string length.

4.7.4. Resource Affinity Procedures

Resource classes and resource class affinities are described in [3].

In this document we use the briefer term resource affinities for the

latter term. Resource classes can be associated with links and

advertised in routing protocols. Resource class affinities are used

by RSVP in two ways. In order to be validated a link MUST pass the

three tests below. If the test fails a PathErr with the code "policy

control failure" SHOULD be sent.

When a new reservation is considered for admission over a strict node

in an ERO, a node MAY validate the resource affinities with the

resource classes of that link. When a node is choosing links in

order to extend a loose node of an ERO, the node MUST validate the

resource classes of those links against the resource affinities. If

no acceptable links can be found to extend the ERO, the node SHOULD

send a PathErr message with an error code of "Routing Problem" and an

error value of "no route available toward destination".

In order to be validated a link MUST pass the following three tests.

To precisely describe the tests use the definitions in the object

description above. We also define

Link-attr A 32-bit vector representing attributes associated

with a link.

The three tests are

1. Exclude-any

This test excludes a link from consideration if the link

carries any of the attributes in the set.

(link-attr & exclude-any) == 0

2. Include-any

This test accepts a link if the link carries any of the

attributes in the set.

(include-any == 0) ((link-attr & include-any) != 0)

3. Include-all

This test accepts a link only if the link carries all of the

attributes in the set.

(include-all == 0) (((link-attr & include-all) ^ include-

all) == 0)

For a link to be acceptable, all three tests MUST pass. If the test

fails, the node SHOULD send a PathErr message with an error code of

"Routing Problem" and an error value of "no route available toward

destination".

If a Path message contains multiple SESSION_ATTRIBUTE objects, only

the first SESSION_ATTRIBUTE object is meaningful. Subsequent

SESSION_ATTRIBUTE objects can be ignored and need not be forwarded.

All RSVP routers, whether they support the SESSION_ATTRIBUTE object

or not, SHALL forward the object unmodified. The presence of non-

RSVP routers anywhere between senders and receivers has no impact on

this object.

5. Hello Extension

The RSVP Hello extension enables RSVP nodes to detect when a

neighboring node is not reachable. The mechanism provides node to

node failure detection. When such a failure is detected it is

handled much the same as a link layer communication failure. This

mechanism is intended to be used when notification of link layer

failures is not available and unnumbered links are not used, or when

the failure detection mechanisms provided by the link layer are not

sufficient for timely node failure detection.

It should be noted that node failure detection is not the same as a

link failure detection mechanism, particularly in the case of

multiple parallel unnumbered links.

The Hello extension is specifically designed so that one side can use

the mechanism while the other side does not. Neighbor failure

detection may be initiated at any time. This includes when neighbors

first learn about each other, or just when neighbors are sharing Resv

or Path state.

The Hello extension is composed of a Hello message, a HELLO REQUEST

object and a HELLO ACK object. Hello processing between two

neighbors supports independent selection of, typically configured,

failure detection intervals. Each neighbor can autonomously issue

HELLO REQUEST objects. Each request is answered by an

acknowledgment. Hello Messages also contain enough information so

that one neighbor can suppress issuing hello requests and still

perform neighbor failure detection. A Hello message may be included

as a sub-message within a bundle message.

Neighbor failure detection is accomplished by collecting and storing

a neighbor's "instance" value. If a change in value is seen or if

the neighbor is not properly reporting the locally advertised value,

then the neighbor is presumed to have reset. When a neighbor's value

is seen to change or when communication is lost with a neighbor, then

the instance value advertised to that neighbor is also changed. The

HELLO objects provide a mechanism for polling for and providing an

instance value. A poll request also includes the sender's instance

value. This allows the receiver of a poll to optionally treat the

poll as an implicit poll response. This optional handling is an

optimization that can reduce the total number of polls and responses

processed by a pair of neighbors. In all cases, when both sides

support the optimization the result will be only one set of polls and

responses per failure detection interval. Depending on selected

intervals, the same benefit can occur even when only one neighbor

supports the optimization.

5.1. Hello Message Format

Hello Messages are always sent between two RSVP neighbors. The IP

source address is the IP address of the sending node. The IP

destination address is the IP address of the neighbor node.

The HELLO mechanism is intended for use between immediate neighbors.

When HELLO messages are being the exchanged between immediate

neighbors, the IP TTL field of all outgoing HELLO messages SHOULD be

set to 1.

The Hello message has a Msg Type of 20. The Hello message format is

as follows:

<Hello Message> ::= <Common Header> [ <INTEGRITY> ]

<HELLO>

5.2. HELLO Object formats

The HELLO Class is 22. There are two C_Types defined.

5.2.1. HELLO REQUEST object

Class = HELLO Class, C_Type = 1

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Src_Instance

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Dst_Instance

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

5.2.2. HELLO ACK object

Class = HELLO Class, C_Type = 2

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Src_Instance

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Dst_Instance

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Src_Instance: 32 bits

a 32 bit value that represents the sender's instance. The

advertiser maintains a per neighbor representation/value. This

value MUST change when the sender is reset, when the node reboots,

or when communication is lost to the neighboring node and

otherwise remains the same. This field MUST NOT be set to zero

(0).

Dst_Instance: 32 bits

The most recently received Src_Instance value received from the

neighbor. This field MUST be set to zero (0) when no value has

ever been seen from the neighbor.

5.3. Hello Message Usage

The Hello Message is completely OPTIONAL. All messages may be

ignored by nodes which do not wish to participate in Hello message

processing. The balance of this section is written assuming that the

receiver as well as the sender is participating. In particular, the

use of MUST and SHOULD with respect to the receiver applies only to a

node that supports Hello message processing.

A node periodically generates a Hello message containing a HELLO

REQUEST object for each neighbor who's status is being tracked. The

periodicity is governed by the hello_interval. This value MAY be

configured on a per neighbor basis. The default value is 5 ms.

When generating a message containing a HELLO REQUEST object, the

sender fills in the Src_Instance field with a value representing it's

per neighbor instance. This value MUST NOT change while the agent is

exchanging Hellos with the corresponding neighbor. The sender also

fills in the Dst_Instance field with the Src_Instance value most

recently received from the neighbor. For reference, call this

variable Neighbor_Src_Instance. If no value has ever been received

from the neighbor or this node considers communication to the

neighbor to have been lost, the Neighbor_Src_Instance is set to zero

(0). The generation of a message SHOULD be suppressed when a HELLO

REQUEST object was received from the destination node within the

prior hello_interval interval.

On receipt of a message containing a HELLO REQUEST object, the

receiver MUST generate a Hello message containing a HELLO ACK object.

The receiver SHOULD also verify that the neighbor has not reset.

This is done by comparing the sender's Src_Instance field value with

the previously received value. If the Neighbor_Src_Instance value is

zero, and the Src_Instance field is non-zero, the

Neighbor_Src_Instance is updated with the new value. If the value

differs or the Src_Instance field is zero, then the node MUST treat

the neighbor as if communication has been lost.

The receiver of a HELLO REQUEST object SHOULD also verify that the

neighbor is reflecting back the receiver's Instance value. This is

done by comparing the received Dst_Instance field with the

Src_Instance field value most recently transmitted to that neighbor.

If the neighbor continues to advertise a wrong non-zero value after a

configured number of intervals, then the node MUST treat the neighbor

as if communication has been lost.

On receipt of a message containing a HELLO ACK object, the receiver

MUST verify that the neighbor has not reset. This is done by

comparing the sender's Src_Instance field value with the previously

received value. If the Neighbor_Src_Instance value is zero, and the

Src_Instance field is non-zero, the Neighbor_Src_Instance is updated

with the new value. If the value differs or the Src_Instance field

is zero, then the node MUST treat the neighbor as if communication

has been lost.

The receiver of a HELLO ACK object MUST also verify that the neighbor

is reflecting back the receiver's Instance value. If the neighbor

advertises a wrong value in the Dst_Instance field, then a node MUST

treat the neighbor as if communication has been lost.

If no Instance values are received, via either REQUEST or ACK

objects, from a neighbor within a configured number of

hello_intervals, then a node MUST presume that it cannot communicate

with the neighbor. The default for this number is 3.5.

When communication is lost or presumed to be lost as described above,

a node MAY re-initiate HELLOs. If a node does re-initiate it MUST

use a Src_Instance value different than the one advertised in the

previous HELLO message. This new value MUST continue to be

advertised to the corresponding neighbor until a reset or reboot

occurs, or until another communication failure is detected. If a new

instance value has not been received from the neighbor, then the node

MUST advertise zero in the Dst_instance value field.

5.4. Multi-Link Considerations

As previously noted, the Hello extension is targeted at detecting

node failures not per link failures. When there is only one link

between neighboring nodes or when all links between a pair of nodes

fail, the distinction between node and link failures is not really

meaningful and handling of such failures has already been covered.

When there are multiple links shared between neighbors, there are

special considerations. When the links between neighbors are

numbered, then Hellos MUST be run on each link and the previously

described mechanisms apply.

When the links are unnumbered, link failure detection MUST be

provided by some means other than Hellos. Each node SHOULD use a

single Hello exchange with the neighbor. The case where all links

have failed, is the same as the no received value case mentioned in

the previous section.

5.5. Compatibility

The Hello extension does not affect the processing of any other RSVP

message. The only effect is to allow a link (node) down event to be

declared sooner than it would have been. RSVP response to that

condition is unchanged.

The Hello extension is fully backwards compatible. The Hello class

is assigned a class value of the form 0bbbbbbb. Depending on the

implementation, implementations that do not support the extension

will either silently discard Hello messages or will respond with an

"Unknown Object Class" error. In either case the sender will fail to

see an acknowledgment for the issued Hello.

6. Security Considerations

In principle these extensions to RSVP pose no security exposures over

and above RFC2205[1]. However, there is a slight change in the

trust model. Traffic sent on a normal RSVP session can be filtered

according to source and destination addresses as well as port

numbers. In this specification, filtering occurs only on the basis

of an incoming label. For this reason an administration may wish to

limit the domain over which LSP tunnels can be established. This can

be accomplished by setting filters on various ports to deny action on

a RSVP path message with a SESSION object of type LSP_TUNNEL_IPv4 (7)

or LSP_TUNNEL_IPv6 (8).

7. IANA Considerations

IANA assigns values to RSVP protocol parameters. Within the current

document an EXPLICIT_ROUTE object and a ROUTE_RECORD object are

defined. Each of these objects contain subobjects. This section

defines the rules for the assignment of subobject numbers. This

section uses the terminology of BCP 26 "Guidelines for Writing an

IANA Considerations Section in RFCs" [15].

EXPLICIT_ROUTE Subobject Type

EXPLICIT_ROUTE Subobject Type is a 7-bit number that identifies

the function of the subobject. There are no range restrictions.

All possible values are available for assignment.

Following the policies outlined in [15], subobject types in the

range 0 - 63 (0x00 - 0x3F) are allocated through an IETF Consensus

action, codes in the range 64 - 95 (0x40 - 0x5F) are allocated as

First Come First Served, and codes in the range 96 - 127 (0x60 -

0x7F) are reserved for Private Use.

ROUTE_RECORD Subobject Type

ROUTE_RECORD Subobject Type is an 8-bit number that identifies the

function of the subobject. There are no range restrictions. All

possible values are available for assignment.

Following the policies outlined in [15], subobject types in the

range 0 - 127 (0x00 - 0x7F) are allocated through an IETF

Consensus action, codes in the range 128 - 191 (0x80 - 0xBF) are

allocated as First Come First Served, and codes in the range 192 -

255 (0xC0 - 0xFF) are reserved for Private Use.

The following assignments are made in this document.

7.1. Message Types

Message Message

Number Name

20 Hello

7.2. Class Numbers and C-Types

Class Class

Number Name

1 SESSION

Class Types or C-Types:

7 LSP Tunnel IPv4

8 LSP Tunnel IPv6

10 FILTER_SPEC

Class Types or C-Types:

7 LSP Tunnel IPv4

8 LSP Tunnel IPv6

11 SENDER_TEMPLATE

Class Types or C-Types:

7 LSP Tunnel IPv4

8 LSP Tunnel IPv6

16 RSVP_LABEL

Class Types or C-Types:

1 Type 1 Label

19 LABEL_REQUEST

Class Types or C-Types:

1 Without Label Range

2 With ATM Label Range

3 With Frame Relay Label Range

20 EXPLICIT_ROUTE

Class Types or C-Types:

1 Type 1 Explicit Route

21 ROUTE_RECORD

Class Types or C-Types:

1 Type 1 Route Record

22 HELLO

Class Types or C-Types:

1 Request

2 Acknowledgment

207 SESSION_ATTRIBUTE

Class Types or C-Types:

1 LSP_TUNNEL_RA

7 LSP Tunnel

7.3. Error Codes and Globally-Defined Error Value Sub-Codes

The following list extends the basic list of Error Codes and Values

that are defined in [RFC2205].

Error Code Meaning

24 Routing Problem

This Error Code has the following globally-defined

Error Value sub-codes:

1 Bad EXPLICIT_ROUTE object

2 Bad strict node

3 Bad loose node

4 Bad initial subobject

5 No route available toward

destination

6 Unacceptable label value

7 RRO indicated routing loops

8 MPLS being negotiated, but a

non-RSVP-capable router stands

in the path

9 MPLS label allocation failure

10 Unsupported L3PID

25 Notify Error

This Error Code has the following globally-defined

Error Value sub-codes:

1 RRO too large for MTU

2 RRO Notification

3 Tunnel locally repaired

7.4. Subobject Definitions

Subobjects of the EXPLICIT_ROUTE object with C-Type 1:

1 IPv4 prefix

2 IPv6 prefix

32 Autonomous system number

Subobjects of the RECORD_ROUTE object with C-Type 1:

1 IPv4 address

2 IPv6 address

3 Label

8. Intellectual Property Considerations

The IETF has been notified of intellectual property rights claimed in

regard to some or all of the specification contained in this

document. For more information consult the online list of claimed

rights.

9. Acknowledgments

This document contains ideas as well as text that have appeared in

previous Internet Drafts. The authors of the current document wish

to thank the authors of those drafts. They are Steven Blake, Bruce

Davie, Roch Guerin, Sanjay Kamat, Yakov Rekhter, Eric Rosen, and Arun

Viswanathan. We also wish to thank Bora Akyol, Yoram Bernet and Alex

Mondrus for their comments on this document.

10. References

[1] Braden, R., Zhang, L., Berson, S., Herzog, S. and S. Jamin,

"Resource ReSerVation Protocol (RSVP) -- Version 1, Functional

Specification", RFC2205, September 1997.

[2] Rosen, E., Viswanathan, A. and R. Callon, "Multiprotocol Label

Switching Architecture", RFC3031, January 2001.

[3] Awduche, D., Malcolm, J., Agogbua, J., O'Dell and J. McManus,

"Requirements for Traffic Engineering over MPLS", RFC2702,

September 1999.

[4] Wroclawski, J., "Specification of the Controlled-Load Network

Element Service", RFC2211, September 1997.

[5] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., Farinacci, D.,

Li, T. and A. Conta, "MPLS Label Stack Encoding", RFC3032,

January 2001.

[6] Bradner, S., "Key words for use in RFCs to Indicate Requirement

Levels", BCP 14, RFC2119, March 1997.

[7] Almquist, P., "Type of Service in the Internet Protocol Suite",

RFC1349, July 1992.

[8] Nichols, K., Blake, S., Baker, F. and D. Black, "Definition of

the Differentiated Services Field (DS Field) in the IPv4 and

IPv6 Headers", RFC2474, December 1998.

[9] Herzog, S., "Signaled Preemption Priority Policy Element", RFC

2751, January 2000.

[10] Awduche, D., Hannan, A. and X. Xiao, "Applicability Statement

for Extensions to RSVP for LSP-Tunnels", RFC3210, December

2001.

[11] Wroclawski, J., "The Use of RSVP with IETF Integrated Services",

RFC2210, September 1997.

[12] Postel, J., "Internet Control Message Protocol", STD 5, RFC792,

September 1981.

[13] Mogul, J. and S. Deering, "Path MTU Discovery", RFC1191,

November 1990.

[14] Conta, A. and S. Deering, "Internet Control Message Protocol

(ICMPv6) for the Internet Protocol Version 6 (IPv6)", RFC2463,

December 1998.

[15] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA

Considerations Section in RFCs", BCP 26, RFC2434, October 1998.

[16] Bernet, Y., Smiht, A. and B. Davie, "Specification of the Null

Service Type", RFC2997, November 2000.

11. Authors' Addresses

Daniel O. Awduche

Movaz Networks, Inc.

7926 Jones Branch Drive, Suite 615

McLean, VA 22102

Voice: +1 703-298-5291

EMail: awduche@movaz.com

Lou Berger

Movaz Networks, Inc.

7926 Jones Branch Drive, Suite 615

McLean, VA 22102

Voice: +1 703 847 1801

EMail: lberger@movaz.com

Der-Hwa Gan

Juniper Networks, Inc.

385 Ravendale Drive

Mountain View, CA 94043

EMail: dhg@juniper.net

Tony Li

Procket Networks

3910 Freedom Circle, Ste. 102A

Santa Clara CA 95054

EMail: tli@procket.com

Vijay Srinivasan

Cosine Communications, Inc.

1200 Bridge Parkway

Redwood City, CA 94065

Voice: +1 650 628 4892

EMail: vsriniva@cosinecom.com

George Swallow

Cisco Systems, Inc.

250 Apollo Drive

Chelmsford, MA 01824

Voice: +1 978 244 8143

EMail: swallow@cisco.com

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