RFC3103 - Realm Specific IP: Protocol Specification

Network Working Group M. Borella

Request for Comments: 3103 D. Grabelsky

Category: EXPerimental CommWorks

J. Lo

Candlestick Networks

K. TanigUChi

NEC USA

October 2001

Realm Specific IP: Protocol Specification

Status of this Memo

This memo defines an Experimental Protocol for the Internet

community. It does not specify an Internet standard of any kind.

Discussion and suggestions for improvement are requested.

Distribution of this memo is unlimited.

IESG Note

The IESG notes that the set of documents describing the RSIP

technology imply significant host and gateway changes for a complete

implementation. In addition, the floating of port numbers can cause

problems for some applications, preventing an RSIP-enabled host from

interoperating transparently with existing applications in some cases

(e.g., IPsec). Finally, there may be significant operational

complexities associated with using RSIP. Some of these and other

complications are outlined in section 6 of the RFC3102, as well as

in the Appendices of RFC3104. Accordingly, the costs and benefits

of using RSIP should be carefully weighed against other means of

relieving address shortage.

Abstract

This document presents a protocol with which to implement Realm

Specific IP (RSIP). The protocol defined herein allows negotiation

of resources between an RSIP host and gateway, so that the host can

lease some of the gateway's addressing parameters in order to

establish a global network presence. This protocol is designed to

operate on the application layer and to use its own TCP or UDP port.

In particular, the protocol allows a gateway to allocate addressing

and control parameters to a host such that a flow policy can be

enforced at the gateway.

Table of Contents

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

2. Specification of Requirements . . . . . . . . . . . . . . . . 4

3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4

4. Architecture . . . . . . . . . . . . . . . . . . . . . . . . 5

5. Transport Protocol . . . . . . . . . . . . . . . . . . . . . 7

6. Host / Gateway Relationships . . . . . . . . . . . . . . . . 7

7. Gateway Flow Policy and State . . . . . . . . . . . . . . . . 8

7.1. Local Flow Policy . . . . . . . . . . . . . . . . . . . . . 9

7.2. Remote Flow Policy . . . . . . . . . . . . . . . . . . . . 9

7.3. Gateway State . . . . . . . . . . . . . . . . . . . . . . . 10

8. Parameter Specification and Formats . . . . . . . . . . . . . 11

8.1. Address . . . . . . . . . . . . . . . . . . . . . . . . . . 11

8.2. Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

8.3. Lease Time . . . . . . . . . . . . . . . . . . . . . . . . 13

8.4. Client ID . . . . . . . . . . . . . . . . . . . . . . . . . 13

8.5. Bind ID . . . . . . . . . . . . . . . . . . . . . . . . . . 13

8.6. Tunnel Type . . . . . . . . . . . . . . . . . . . . . . . . 14

8.7. RSIP Method . . . . . . . . . . . . . . . . . . . . . . . . 14

8.8. 8.8. Error . . . . . . . . . . . . . . . . . . . . . . . . 14

8.9. Flow Policy . . . . . . . . . . . . . . . . . . . . . . . . 15

8.10. Indicator . . . . . . . . . . . . . . . . . . . . . . . . 15

8.11. Message Counter . . . . . . . . . . . . . . . . . . . . . 16

8.12. Vendor Specific Parameter . . . . . . . . . . . . . . . . 16

9. Message Types . . . . . . . . . . . . . . . . . . . . . . . . 16

9.1. ERROR_RESPONSE . . . . . . . . . . . . . . . . . . . . . . 17

9.2. REGISTER_REQUEST . . . . . . . . . . . . . . . . . . . . . 18

9.3. REGISTER_RESPONSE . . . . . . . . . . . . . . . . . . . . . 19

9.4. DE-REGISTER_REQUEST . . . . . . . . . . . . . . . . . . . . 19

9.5. DE-REGISTER_RESPONSE . . . . . . . . . . . . . . . . . . . 20

9.6. ASSIGN_REQUEST_RSA-IP . . . . . . . . . . . . . . . . . . . 21

9.7. ASSIGN_RESPONSE_RSA-IP . . . . . . . . . . . . . . . . . . 22

9.8. ASSIGN_REQUEST_RSAP-IP . . . . . . . . . . . . . . . . . . 23

9.9. ASSIGN_RESPONSE_RSAP-IP . . . . . . . . . . . . . . . . . . 26

9.10. EXTEND_REQUEST . . . . . . . . . . . . . . . . . . . . . . 27

9.11. EXTEND_RESPONSE . . . . . . . . . . . . . . . . . . . . . 28

9.12. FREE_REQUEST . . . . . . . . . . . . . . . . . . . . . . . 28

9.13. FREE_RESPONSE . . . . . . . . . . . . . . . . . . . . . . 29

9.14. QUERY_REQUEST . . . . . . . . . . . . . . . . . . . . . . 30

9.15. QUERY_RESPONSE . . . . . . . . . . . . . . . . . . . . . . 31

9.16. LISTEN_REQUEST . . . . . . . . . . . . . . . . . . . . . . 32

9.17. LISTEN_RESPONSE . . . . . . . . . . . . . . . . . . . . . 35

10. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . 36

10.1. Use of Message Counters . . . . . . . . . . . . . . . . . 36

10.2. RSIP Host and Gateway Failure Scenarios . . . . . . . . . 37

10.3. General Gateway Policy . . . . . . . . . . . . . . . . . . 38

10.4. Errors Not From the RSIP Protocol . . . . . . . . . . . . 39

10.5. Address and Port Requests and Allocation . . . . . . . . . 40

10.6. Local Gateways and Flow Policy Interaction . . . . . . . . 40

11. Security Considerations . . . . . . . . . . . . . . . . . . 40

12. IANA Considerations . . . . . . . . . . . . . . . . . . . . 41

13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 41

14. Appendix A: RSIP Error Numbers . . . . . . . . . . . . . . . 42

15. Appendix B: Message Types . . . . . . . . . . . . . . . . . 44

16. Appendix C: Example RSIP host/gateway transactions . . . . . 45

17. Appendix D: Example RSIP host state diagram . . . . . . . . 50

18. References . . . . . . . . . . . . . . . . . . . . . . . . . 52

19. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 53

20. Full Copyright Statement . . . . . . . . . . . . . . . . . . 54

1. Introduction

Network Address Translation (NAT) has gained popularity as a method

of separating public and private address spaces, and alleviating

network address shortages. A NAT translates the addresses of packets

leaving a first routing realm to an address from a second routing

realm, and performs the reverse function for packets entering the

first routing realm from the second routing realm. This translation

is performed transparently to the hosts in either space, and may

include modification of TCP/UDP port numbers and IP addresses in

packets that traverse the NAT.

While a NAT does not require hosts to be aware of the translation, it

will require an application layer gateway (ALG) for any protocol that

transmits IP addresses or port numbers in packet payloads (such as

FTP). Additionally, a NAT will not work with protocols that require

IP addresses and ports to remain unmodified between the source and

destination hosts, or protocols that prevent such modifications from

occurring (such as some IPsec modes, or application-layer end-to-end

encryption).

An alternative to a NAT is an architecture that allows the hosts

within the first (e.g., private) routing realm to directly use

addresses and other routing parameters from the second (e.g., public)

routing realm. Thus, RSIP [RSIP-FRAME] has been defined as a method

for address sharing that exhibits more transparency than NAT. In

particular, RSIP requires that an RSIP gateway (a router or gateway

between the two realms) assign at least one address from the second

routing realm, and perhaps some other resources, to each RSIP host.

An RSIP host is a host in the first routing realm that needs to

establish end-to-end connectivity to a host, entity or device in the

second routing realm. Thus, the second routing realm is not directly

Accessible from the RSIP host, but this system allows packets to

maintain their integrity from the RSIP host to their destination.

ALGs are not required in the RSIP gateway.

RSIP requires that hosts be modified so that they place some number

of layer three, layer four or other values from those assigned by the

RSIP gateway in each packet bound for the second routing realm.

This document discusses a method for assigning parameters to an RSIP

host from an RSIP gateway. The requirements, scope, and

applicability of RSIP, as well as its interaction with other layer 3

protocols, are discussed in a companion framework document [RSIP-

FRAME]. Extensions to this protocol that enable end-to-end IPsec are

discussed in [RSIP-IPSEC].

2. Specification of Requirements

The keyWords "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",

"SHALL", "SHALL NOT", "MAY" and "MAY NOT" that appear in this

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

3. Terminology

Private Realm

A routing realm that uses private IP addresses from the ranges

(10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) specified in

[RFC1918], or addresses that are non-routable from the Internet.

Public Realm

A routing realm with unique network addresses assigned by the

Internet Assigned Number Authority (IANA) or an equivalent address

registry.

RSIP Host

A host within the private realm that acquires publicly unique

parameters from an RSIP gateway through the use of the RSIP

client/server protocol.

RSIP Gateway

A router situated on the boundary between a private realm and a

public realm and owns one or more public IP addresses. An RSIP

gateway is responsible for public parameter management and

assignment to RSIP hosts. An RSIP gateway may act as a NAT router

for hosts within the private realm that are not RSIP enabled.

RSIP Client

An application program that performs the client portion of the

RSIP client/server protocol. An RSIP client application MUST

exist on all RSIP hosts, and MAY exist on RSIP gateways.

RSIP Server

An application program that performs the server portion of the

RSIP client/server protocol. An RSIP server application MUST

exist on all RSIP gateways.

RSA-IP: Realm Specific Address IP

An RSIP method in which each RSIP host is allocated a unique IP

address from the public realm. Discussed in detail in [RSIP-

FRAME]

RSAP-IP: Realm Specific Address and Port IP

An RSIP method in which each RSIP host is allocated an IP address

(possibly shared with other RSIP hosts) and some number of per-

address unique ports from the public realm. Discussed in detail

in [RSIP-FRAME]

Binding

An association of some combination of a local address, one or more

local ports, a remote address, and a remote port with an RSIP

host.

Resource

A general way to refer to an item that an RSIP host leases from an

RSIP gateway; e.g., an address or port.

All other terminology found in this document is consistent with that

of [RFC2663] and [RSIP-FRAME].

4. Architecture

For simplicity, in the remainder of this document we will assume that

the RSIP hosts in the first routing realm (network) use private

(e.g., see [RFC1918]) IP addresses, and that the second routing realm

(network) uses public IP addresses. (This assumption is made without

loss of generality and the ensuing discussion applies to more general

cases.) The RSIP gateway connects the public and private realms and

contains interfaces to both. Other NAT terminology found in this

document is defined in [RFC2663].

The diagram below describes an exemplary reference architecture for

RSIP.

RSIP Host RSIP Gateway Host

Xa Na Nb Yb

[X]------( Addr sp. A )----[N]-----( Addr sp. B )-------[Y]

( Network ) ( Network )

Hosts X and Y belong to different addressing realms A and B,

respectively, and N is an RSIP gateway (which may also perform NAT

functions). N has two interfaces: Na on address space A, and Nb on

address space B. N may have a pool of addresses in address space B

which it can assign to or lend to X and other hosts in address space

A. These addresses are not shown above, but they can be denoted as

Nb1, Nb2, Nb3 and so on.

Host X, needing to establish an end-to-end connection to a network

entity Y situated within address space B, first negotiates and

oBTains assignment of the resources from the RSIP gateway. Upon

assignment of these parameters, the RSIP gateway creates a mapping,

of X's addressing information and the assigned resources. This

binding enables the RSIP gateway to correctly de-multiplex and

forward inbound traffic generated by Y for X. A lease time is

associated with each bind.

Using the public parameters assigned by the RSIP gateway, RSIP hosts

tunnel data packets across address space A to the RSIP gateway. The

RSIP gateway acts as the end point of such tunnels, stripping off the

outer headers and routing the inner packets onto the public realm.

As mentioned above, an RSIP gateway maintains a mapping of the

assigned public parameters as demultiplexing fields for uniquely

mapping them to RSIP host private addresses. When a packet from the

public realm arrives at the RSIP gateway and it matches a given set

of demultiplexing fields, then the RSIP gateway will tunnel it to the

appropriate RSIP host. The tunnel headers of outbound packets from X

to Y, given that X has been assigned Nb, are as follows:

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

X -> Na Nb -> Y payload

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

There are two basic flavors of RSIP: RSA-IP and RSAP-IP. RSIP hosts

and gateways MUST support RSAP-IP and MAY support RSA-IP. Details of

RSA-IP and RSAP-IP are found in [RSIP-FRAME].

5. Transport Protocol

RSIP is an application layer protocol that requires the use of a

transport layer protocol for end-to-end delivery of packets.

RSIP gateways MUST support TCP, and SHOULD support UDP. Due to the

fact that RSIP may be deployed across a wide variety of network

links, RSIP hosts SHOULD support TCP, because of TCP's robustness

across said variety of links. However, RSIP hosts MAY support UDP

instead of TCP, or both UDP and TCP.

For RSIP hosts and gateways using UDP, timeout and retransmissions

MUST occur. We recommend a binary exponential bacKOFf scheme with an

initial duration of 12.5 ms, and a maximum of six retries (seven

total attempts before failure). However, these parameters MAY be

adjusted or tuned for specific link types or scenarios.

Once a host and gateway have established a registration using either

TCP or UDP, they may not switch between the two protocols for the

duration of the registration. The decision of whether to use TCP or

UDP is made by the client, and is determined by the transport

protocol of the first packet sent by a client in a successful

registration procedure.

6. Host / Gateway Relationships

An RSIP host can be in exactly one of three fundamental relationships

with respect to an RSIP gateway:

Unregistered: The RSIP gateway does not know of the RSIP host's

existence, and it will not forward or deliver globally addressed

packets on behalf of the host. The only valid RSIP-related action

for an RSIP host to perform in this state is to request

registration with an RSIP gateway.

Registered: The RSIP gateway knows of the RSIP host and has assigned

it a client ID and has specified the flow policies that it

requires of the host. However, no resources, such as addresses or

ports, have been allocated to the host, and the gateway will not

forward or deliver globally addressed packets on behalf of the

host. All registrations have an associated lease time. If this

lease time expires, the RSIP host automatically reverts to the

unregistered state.

Assigned: The RSIP gateway has granted one or more bindings of

resources to the host. The gateway will forward and deliver

globally addressed packets on behalf of the host. Each binding

has an associated lease time. If this lease time expires, the

binding is automatically revoked.

Architectures in which an RSIP host is simultaneously registered with

more than one RSIP gateway are possible. In such cases, an RSIP host

may be in different relationships with different RSIP gateways at the

same time.

An RSIP gateway MAY redirect an RSIP host to use a tunnel endpoint

for data traffic that is not the RSIP gateway itself, or perhaps is a

different interface on the RSIP gateway. This is done by specifying

the tunnel endpoint's address as part of an assignment. In such an

architecture, it is desirable (though not necessary) for the RSIP

gateway to have a method with which to notify the tunnel endpoint of

assignments, and the expiration status of these assignments.

Lease times for bindings and registrations are managed as follows.

All lease times are given in units of seconds from the current time,

indicating a time in the future at which the lease will expire.

These expiration times are used in the ensuing discussion.

An initial expiration time (R) is given to a registration. Under

this registration, multiple bindings may be established, each with

their own expiration times (B1, B2, ...). When each binding is

established or extended, the registration expiration time is adjusted

so that the registration will last at least as long as the longest

lease. In other words, when binding Bi is established or extended,

the following calculation is performed: R = max(R, Bi).

Under this scheme, a registration will never expire while any

binding's lease is still valid. However, a registration may expire

when the last binding's lease expires, or at some point thereafter.

7. Gateway Flow Policy and State

Since an RSIP gateway is likely to reside on the boundary between two

or more different administrative domains, it is desirable to enable

an RSIP gateway to be able to enforce flow-based policy. In other

words, an RSIP gateway should have the ability to explicitly control

which local addresses and ports are used to communicate with remote

addresses and ports.

In the following, macro-flow policy refers to controlling flow policy

at the granularity level of IP addresses, while micro-flow policy

refers to controlling flow policy at the granularity of IP address

and port tuples. Of course there may be no policy at all, which

indicates that the RSIP gateway does not care about the flow

parameters used by RSIP hosts. We consider two levels of local flow

policy and three levels of remote flow policy.

7.1. Local Flow Policy

Local flow policy determines the granularity of control that an RSIP

gateway has over the local addressing parameters that an RSIP host

uses for particular sessions.

Since an RSIP host must use at least an IP address allocated by the

gateway, the loosest level of local flow policy is macro-flow based.

Under local macro-flow policy, an RSIP host is allocated an IP

address (RSA-IP) or an IP address and one or more ports to use with

it (RSAP-IP). However, the host may use the ports as it desires for

establishing sessions with public hosts.

Under micro-flow policy, a host is allocated exactly one port at a

time. The host may request more ports, also one at a time. This

policy gives the gateway very tight control over local port use,

although it affords the host less flexibility.

Note that only local macro-flow policy can be used with RSA-IP, while

either local macro-flow or local micro-flow policy may be used with

RSAP-IP.

Examples of how RSIP flow policy operates are given in Appendix C.

7.2. Remote Flow Policy

Remote flow policy determines the granularity of control that an RSIP

gateway has over the remote (public) hosts with which an RSIP host

communicates. In particular, remote flow policy dictates what level

of detail that a host must specify addressing parameters of a remote

host or application before the RSIP gateway allows the host to

communicate with that host or application.

The simplest and loosest form of flow policy is no policy at all. In

other words, the RSIP gateway allocates addressing parameters to the

host, and the host may use these parameters to communicate with any

remote host, without explicitly notifying the gateway.

Macro-flow policy requires that the host identify the remote address

of the host that it wishes to communicate with as part of its request

for local addressing parameters. If the request is granted, the host

MUST use the specified local parameters only with the remote address

specified, and MUST NOT communicate with the remote address using any

local parameters but the ones allocated. However, the host may

contact any port number at the remote host without explicitly

notifying the gateway.

Micro-flow policy requires that the host identify the remote address

and port of the host that it wishes to communicate with as part of

its request for local addressing parameters. If the request is

granted, the host MUST use the specified local parameters only with

the remote address and port specified, and MUST NOT communicate with

the remote address and port using any local parameters but the ones

allocated.

Remote flow policy is implemented in both the ingress and egress

directions, with respect to the location of the RSIP gateway.

7.3. Gateway State

An RSIP gateway must maintain state for all RSIP hosts and their

assigned resources. The amount and type of state maintained depends

on the local and remote flow policy. The required RSIP gateway state

will vary based on the RSIP method, but will always include the

chosen method's demultiplexing parameters.

7.3.1. RSA-IP State

An RSIP gateway serving an RSIP host using the RSA-IP method MUST

maintain the following minimum state to ensure proper mapping of

incoming packets to RSIP hosts:

- Host's private address

- Host's assigned public address(es)

7.3.2. RSAP-IP State

An RSIP gateway serving an RSIP host using the RSAP-IP method MUST

maintain the following minimum state to ensure proper mapping of

incoming packets to RSIP hosts:

- Host's private address

- Host's assigned public address(es)

- Host's assigned port(s) per address

7.3.3. Flow State

Regardless of whether the gateway is using RSA-IP or RSAP-IP,

additional state is necessary if either micro-flow based or macro-

flow based remote policy is used.

If the gateway is using macro-flow based remote policy, the following

state must be maintained:

- Remote host's address

If the gateway is using micro-flow based remote policy, the following

state must be maintained:

- Remote host's address

- Remote host's port

More state MAY be used by an RSIP gateway if desired. For example,

ToS/DS bytes may be recorded in order to facilitate quality of

service support.

8. Parameter Specification and Formats

In this section we define the formats for RSIP parameters. Each RSIP

message contains one or more parameters that encode the information

passed between the host and gateway. The general format of all

parameters is TLV (type-length-value) consisting of a 1-byte type

followed by a 2-byte length followed by a 'length' byte value as

shown below.

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 Value

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

Value ...

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

The value field may be divided into a number of other fields as per

the type of the parameter. Note that the length field encodes the

number of bytes in the value field, NOT the overall number of bytes

in the parameter.

8.1. 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 = 1 Length Addrtype

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

Address...

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

The address parameter contains addressing information, either an IPv4

address or netmask, an IPv6 address or netmask, or a fully qualified

domain name (FQDN). The Addrtype field is 1 byte in length,

indicating the type of address.

Addrtype Length of address field (in bytes)

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

0 Reserved 0

1 IPv4 4

2 IPv4 netmask 4

3 IPv6 16

4 FQDN varies

For FQDN (Fully qualified domain name), the length of the address

field will be one less than the value of the length field, and the

name will be represented as an ASCII string (no terminating

character).

In some cases, it is necessary to specify a "don't care" value for an

address. This is signified by a setting the length field to 1 and

omitting the value field.

It is not valid for a host to request an address with an FQDN type as

its local address (See specification of ASSIGN_REQUEST_RSA-IP and

ASSIGN_REQUEST_RSAP-IP, below).

8.2. Ports

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 = 2 Length Number

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

Port number ...

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

The ports parameter encodes zero or more TCP or UDP ports. When a

single port is specified, the value of the number field is 1 and

there is one port field following the number field. When more than

one port is specified, the value of the number field will indicate

the total number of ports contained, and the parameter may take one

of two forms. If there is one port field, the ports specified are

considered to be contiguous starting at the port number specified in

the port field. Alternatively, there may be a number of port fields

equal to the value of the number field. The number of port fields

can be extrapolated from the length field.

In some cases, it is necessary to specify a don't care value for one

or more ports (e.g., when a client application is using ephemeral

source ports). This is accomplished by setting the length field to

1, setting the number field to the number of ports necessary, and

omitting all port fields. The value of the number field MUST be

greater than or equal to one.

If micro-flow based policy applies to a given ports parameter, it

MUST contain exactly one port field.

8.3. Lease Time

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 = 3 Length = 4 Lease time

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

Lease time

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

The lease time parameter specifies the length, in seconds, of an

RSIP host registration or parameter binding.

8.4. Client ID

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 = 4 Length = 4 Client ID

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

Client ID

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

The client ID parameter specifies an RSIP client ID. Client ID's

by an RSIP gateway to differentiate RSIP hosts.

8.5. Bind ID

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 = 5 Length = 4 Bind ID

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

Bind ID

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

The bind ID parameter specifies an RSIP bind ID. Bind ID's are used

by RSIP hosts and gateways to differentiate an RSIP host's bindings.

8.6. Tunnel Type

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 = 6 Length = 1 Tunnel type

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

The tunnel type parameter specifies the type of tunnel used between

an RSIP host and an RSIP gateway. Defined tunnel types are:

Tunnel Type

-----------

0 Reserved

1 IP-IP

2 GRE

3 L2TP

8.7. RSIP Method

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 = 7 Length = 1 RSIP method

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

The RSIP method parameter specifies an RSIP method. Defined RSIP

methods are:

RSIP method

-----------

0 Reserved

1 RSA-IP

2 RSAP-IP

8.8. Error

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 = 8 Length = 2 Error

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

Error

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

The error parameter specifies an error. The currently defined error

values are presented in Appendix A.

8.9. Flow Policy

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 = 9 Length = 2 Local

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

Remote

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

The flow policy parameter specifies both the local and remote flow

policy.

Defined local flow policies are:

Local Flow Policy

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

0 Reserved

1 Macro flows

2 Micro flows

Defined remote flow policies are:

Remote Flow Policy

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

0 Reserved

1 Macro flows

2 Micro flows

3 No policy

8.10. Indicator

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 = 10 Length = 2 Value

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

Value

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

An indicator parameter is a general-purpose parameter, the use of

which is defined by the message that it appears in. An RSIP message

that uses an indicator parameter MUST define the meaning and

interpretation of all of the indicator's possible values.

8.11. Message Counter

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 = 11 Length = 4 Counter

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

Counter

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

A message counter parameter is used to mark RSIP messages with

sequentially-increasing values. Message counters MUST be used with

UDP, in order to facilitate reliability.

8.12. Vendor Specific Parameter

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 = 12 Length Vendor ID

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

Vendor ID Subtype Value...

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

The vendor specific parameter is used to encode parameters that are

defined by a particular vendor. The vendor ID field is the vendor-

specific ID assigned by IANA. Subtypes are defined and used by each

vendor as necessary. An RSIP host or gateway SHOULD silently ignore

vendor-specific messages that it does not understand.

9. Message Types

RSIP messages consist of three mandatory fields, version, message

type, and overall length, followed by one or more required

parameters, followed in turn by zero or more optional parameters. In

an RSIP message, all required parameters MUST appear in the exact

order specified below. Optional parameters MAY appear in any order.

Message format is shown below:

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

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

Version Message type Overall length

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

Parameters...

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

The version number field is a single byte and specifies the RSIP

version number that is being used. The current RSIP version number

is 1.

The message type field is a single byte and specifies the message

contained in the current packet. There may be only one message per

packet. Message types are given numerical assignments in Appendix B.

The overall length field is two bytes and contains the number of

bytes in the RSIP message, including the three mandatory fields.

Most parameters are only allowed to appear once in each message. The

exceptions are as follows:

- Multiple address parameters MUST appear in ASSIGN_REQUEST_RSA-

IP, ASSIGN_RESPONSE_RSA-IP, ASSIGN_REQUEST_RSAP-IP,

ASSIGN_RESPONSE_RSAP-IP, LISTEN_REQUEST and LISTEN_RESPONSE.

- Multiple ports parameters MUST appear in ASSIGN_REQUEST_RSAP-

IP, ASSIGN_RESPONSE_RSAP-IP, LISTEN_REQUEST and

LISTEN_RESPONSE.

- Multiple RSIP method and tunnel type parameters MAY appear in

RESISTER_RESPONSE.

- Multiple address parameters and multiple indicator parameters

MAY appear in QUERY_REQUEST and QUERY_RESPONSE.

The following message types are defined in BNF. Required parameters

are enclosed in <> and MUST appear. Optional parameters are enclosed

in [] and MAY appear. Not all message types need to be implemented

in order to be RSIP compliant. For example, an RSIP host and/or

gateway may not support LISTEN_REQUEST and LISTEN_RESPONSE, or may

only support RSAP-IP and not RSA-IP.

9.1. ERROR_RESPONSE

9.1.1. Description

An ERROR_RESPONSE is used to provide error messages from an RSIP

gateway to an RSIP host. Usually, errors indicate that the RSIP

gateway cannot or will not perform an action or allocate resources on

behalf of the host. If the error is related to a particular client

ID or bind ID, these associated parameters MUST be included.

Multiple errors MAY NOT be reported in the same ERROR_RESPONSE. In

situations where more than one error has occurred, the RSIP gateway

MUST choose only one error to report.

9.1.2. Format

<ERROR_RESPONSE> ::= <Version>

<Error>

[Message Counter]

[Client ID]

[Bind ID]

9.1.3. Behavior

An ERROR_RESPONSE message MUST only be transmitted by an RSIP

gateway. An RSIP host that detects an error in a message received

from an RSIP gateway MUST silently discard the message. There are no

error conditions that can be caused by an ERROR_RESPONSE. An

ERROR_RESPONSE is typically transmitted in response to a request from

an RSIP host, but also may be transmitted asynchronously by an RSIP

gateway.

9.2. REGISTER_REQUEST

9.2.1. Description

The REGISTER_REQUEST message is used by an RSIP host to establish

registration with an RSIP gateway. An RSIP host MUST register before

it requests resources or services from an RSIP gateway. Once an RSIP

host has registered with an RSIP gateway, it may not register again

until it has de-registered from that gateway.

9.2.2. Format

<REGISTER_REQUEST> ::= <Version>

[Message Counter]

9.2.3. Behavior

The following message-specific error conditions exist:

- If the host is already registered with the gateway, the gateway

MUST respond with an ERROR_RESPONSE containing the

ALREADY_REGISTERED error and the RSIP host's client ID.

- If the gateway's policy will not allow the host to register,

the gateway MUST respond with an ERROR_RESPONSE containing the

REGISTRATION_DENIED error.

9.3. REGISTER_RESPONSE

9.3.1. Description

The REGISTER_RESPONSE message is used by an RSIP gateway to confirm

the registration of an RSIP host, and to provide a client ID, flow

policy, and possibly a message counter and one or more RSIP methods

and/or tunnel types.

9.3.2. Format

<REGISTER_RESPONSE> ::= <Version>

[Message Counter]

[RSIP Method]...

[Tunnel Type]...

9.3.3. Behavior

An RSIP gateway MUST assign a different client ID to each host that

is simultaneously registered with it. The RSIP gateway MAY respond

with one or more RSIP methods and tunnel types that it supports. If

an RSIP method is not specified, RSAP-IP MUST be assumed. If a

tunnel type is not specified, IP-IP MUST be assumed.

9.4. DE-REGISTER_REQUEST

9.4.1. Description

The DE-REGISTER_REQUEST message is used by an RSIP host to de-

assigned state, all of the host's bindings are revoked. The host

SHOULD NOT de-register from the unregistered state.

9.4.2. Format

<DE-REGISTER_REQUEST> ::= <Version>

[Message Counter]

9.4.3. Behavior

The following message-specific error conditions exist:

- If the host is not registered with the gateway, the gateway

MUST respond with an ERROR_RESPONSE containing the

REGISTER_FIRST error.

- If the message contains an incorrect client ID, the gateway

MUST respond with an ERROR_RESPONSE containing the

BAD_CLIENT_ID error.

If there are no errors that result from this message, the gateway

MUST respond with an appropriate DE-REGISTER_RESPONSE. Upon de-

registering a host, an RSIP gateway must delete all binds associated

with that host and return their resources to the pool of free

resources. Once a host has de-registered, it may not use any of the

RSIP gateway's resources without registering again.

9.5. DE-REGISTER_RESPONSE

9.5.1. Description

The DE-REGISTER_RESPONSE message is used by an RSIP gateway to

confirm the de-registration of an RSIP host or to force an RSIP host

to relinquish all of its bindings and terminate its relationship with

the RSIP gateway. Upon receiving a DE-REGISTER_RESPONSE message, an

RSIP host MUST stop all use of the resources that have been allocated

to it by the gateway.

9.5.2. Format

<DE-REGISTER_RESPONSE> ::= <Version>

[Message Counter]

9.5.3. Behavior

An RSIP gateway MUST send a DE-REGISTER_RESPONSE in response to a

valid DE-REGISTER_REQUEST. An RSIP gateway MUST send a DE-

REGISTER_RESPONSE to an RSIP host when that host's registration lease

time times out. An RSIP gateway SHOULD send a DE-REGISTER_RESPONSE

if it detects that it will no longer be able to perform RSIP

functionality for a given host. An RSIP host MUST be ready to accept

a DE-REGISTER_RESPONSE at any moment.

9.6. ASSIGN_REQUEST_RSA-IP

9.6.1. Description

The ASSIGN_REQUEST_RSA-IP message is used by an RSIP host to request

resources to use with RSA-IP. Note that RSA-IP cannot be used in

combination with micro-flow based local policy.

9.6.2. Format

<ASSIGN_REQUEST_RSA-IP> ::= <Version>

[Message Counter]

[Lease Time]

[Tunnel Type]

9.6.3. Behavior

The RSIP host specifies two address parameters. The RSIP host may

request a particular local address by placing that address in the

first address parameter. To indicate that it has no preference for

local address, the RSIP host may place a "don't care" value in the

address parameter.

If macro-flow based remote policy is used, the host MUST specify the

remote address that it will use this binding (if granted) to contact;

however, the remote port number MAY remain unspecified. If micro-

flow based remote policy is used, the host MUST specify the remote

address and port number that it will use this binding (if granted) to

contact. If no flow policy is used, the RSIP host may place a "don't

care" value in the value fields of the respective address and ports

parameters.

The following message-specific error conditions exist:

- If the host is not registered with the gateway, the gateway

MUST respond with an ERROR_RESPONSE containing the

REGISTER_FIRST error.

- If the message contains an incorrect client ID, the gateway

MUST respond with an ERROR_RESPONSE containing the

BAD_CLIENT_ID error.

- If the local address parameter is a don't care value and the

RSIP gateway cannot allocate ANY addresses, the RSIP gateway

MUST respond with an ERROR_RESPONSE containing the

LOCAL_ADDR_UNAVAILABLE error.

- If the local address parameter is not a don't care value there

are three possible error conditions:

o If the RSIP gateway cannot allocate ANY addresses, it MUST

respond with an ERROR_RESPONSE containing the

LOCAL_ADDR_UNAVAILABLE error.

o If the RSIP gateway cannot allocate the requested address

because it is in use, the RSIP gateway MUST respond with an

ERROR_RESPONSE containing the LOCAL_ADDR_INUSE error.

o If the RSIP gateway cannot allocate the requested address

because it is not allowed by policy, the RSIP gateway MUST

respond with an ERROR_RESPONSE containing the

LOCAL_ADDR_UNALLOWED error.

- If macro-flow based remote policy is used and the requested

remote address is not allowed by the RSIP gateway's policy, the

RSIP gateway MUST respond with an ERROR_RESPONSE containing the

REMOTE_ADDR_UNALLOWED error.

- If micro-flow based remote policy is used and the requested

remote address / port pair is not allowed by the RSIP gateway's

policy, the RSIP gateway MUST respond with an ERROR_RESPONSE

containing the REMOTE_ADDRPORT_UNALLOWED error.

- If an unsupported or unallowed tunnel type is specified, the

RSIP gateway MUST respond with an ERROR_RESPONSE containing the

BAD_TUNNEL_TYPE error.

- If the host has not specified local or remote address or port

information in enough detail, the RSIP gateway MUST respond

with an ERROR_RESPONSE containing the FLOW_POLICY_VIOLATION

error.

9.7. ASSIGN_RESPONSE_RSA-IP

9.7.1. Description

The ASSIGN_RESPONSE_RSA-IP message is used by an RSIP gateway to

deliver parameter assignments to an RSIP host using RSA-IP. A host-

wise unique bind ID, lease time, and tunnel type must be provided for

every assignment.

9.7.2. Format

<ASSIGN_RESPONSE_RSA-IP> ::= <Version>

[Address (tunnel endpoint)]

[Message Counter]

9.7.3. Behavior

If no remote flow policy is used, the RSIP gateway MUST use "don't

care" values for the remote address and ports parameters. If macro-

flow based remote policy is used, the remote address parameter MUST

contain the address specified in the associated request, and the

remote ports parameter MUST contain a "don't care" value. If micro-

flow based remote policy is used, the remote address and remote ports

parameters MUST contain the address and port information specified in

the associated request.

If the host detects an error or otherwise does not "understand" the

gateway's response, it SHOULD send a FREE_REQUEST with the bind ID

from the said ASSIGN_RESPONSE_RSA-IP. This will serve to help

synchronize the states of the host and gateway.

The address of a tunnel endpoint that is not the RSIP gateway MAY be

specified. If this parameter is not specified, the RSIP gateway MUST

be assumed to be the tunnel endpoint.

9.8. ASSIGN_REQUEST_RSAP-IP

9.8.1. Description

The ASSIGN_REQUEST_RSAP-IP message is used by an RSIP host to request

resources to use with RSAP-IP. The RSIP host specifies two address

and two port parameters, the first of each, respectively, refer to

the local address and port(s) that will be used, and the second of

each, respectively, refer to the remote address and port(s) that will

be contacted.

9.8.2. Format

<ASSIGN_REQUEST_RSAP-IP> ::= <Version>

[Message Counter]

[Lease Time]

[Tunnel Type]

9.8.3. Behavior

An RSIP host may request a particular local address by placing that

address in the value field of the first address parameter. The RSIP

host may request particular local ports by placing them in the first

port parameter. To indicate that it has no preference for local

address or ports, the RSIP host may place a "don't care" value in the

respective address or ports parameters.

If macro-flow based remote policy is used, the host MUST specify the

remote address that it will use this binding (if granted) to contact;

however, the remote port number(s) MAY remain unspecified. If

micro-flow based remote policy is used, the host MUST specify the

remote address and port number(s) that it will use this binding (if

granted) to contact. If no flow policy is used, the RSIP host may

place a value of all 0's in the value fields of the respective

address or port parameters.

The following message-specific error conditions exist:

- If the host is not registered with the gateway, the gateway

MUST respond with an ERROR_RESPONSE containing the

REGISTER_FIRST error.

- If the message contains an incorrect client ID, the gateway

MUST respond with an ERROR_RESPONSE containing the

BAD_CLIENT_ID error.

- If the local address parameter is a don't care value and the

RSIP gateway cannot allocate ANY addresses, the RSIP gateway

MUST respond with an ERROR_RESPONSE containing the

LOCAL_ADDR_UNAVAILABLE error.

- If the local address parameter is not a don't care value there

are five possible error conditions:

o If the RSIP gateway cannot allocate ANY addresses, it MUST

respond with an ERROR_RESPONSE containing the

LOCAL_ADDR_UNAVAILABLE error.

o If the RSIP gateway cannot allocate the requested address

because it is in use, the RSIP gateway MUST respond with an

ERROR_RESPONSE containing the LOCAL_ADDR_INUSE error.

o If the RSIP gateway cannot allocate the requested address

because it is not allowed by policy, the RSIP gateway MUST

respond with an ERROR_RESPONSE containing the

LOCAL_ADDR_UNALLOWED error.

o If the RSIP gateway cannot allocate a requested address /

port tuple because it is in use, the RSIP gateway MUST

respond with an ERROR_RESPONSE containing the

LOCAL_ADDRPORT_INUSE error.

o If the RSIP gateway cannot allocate a requested address /

port tuple because it is not allowed by policy, the RSIP

gateway MUST respond with an ERROR_RESPONSE containing the

LOCAL_ADDRPORT_UNALLOWED error.

- If the RSIP host requests a number of ports (greater that one),

but does not specify particular port numbers (i.e., uses "don't

care" values) the RSIP gateway cannot grant the entire request,

the RSIP gateway MUST return an ERROR_RESPONSE containing the

LOCAL_ADDRPORT_UNAVAILABLE error.

- If macro-flow based remote policy is used and the requested

remote address is not allowed by the RSIP gateway's policy, the

RSIP gateway MUST respond with an ERROR_RESPONSE containing the

REMOTE_ADDR_UNALLOWED error.

- If micro-flow based remote policy is used and the requested

remote address / port pair is not allowed by the RSIP gateway's

policy, the RSIP gateway MUST respond with an ERROR_RESPONSE

containing the REMOTE_ADDRPORT_UNALLOWED error.

- If an unsupported or unallowed tunnel type is specified, the

RSIP gateway MUST respond with an ERROR_RESPONSE containing the

BAD_TUNNEL_TYPE error.

- If the host has not specified local or remote address or port

information in enough detail, the RSIP gateway MUST respond

with an ERROR_RESPONSE containing the FLOW_POLICY_VIOLATION

error.

9.9. ASSIGN_RESPONSE_RSAP-IP

9.9.1. Description

The ASSIGN_RESPONSE_RSAP-IP message is used by an RSIP gateway to

deliver parameter assignments to an RSIP host. A host-wise unique

bind ID, lease time, and tunnel type must be provided for every

assignment.

9.9.2. Format

<ASSIGN_RESPONSE_RSAP-IP> ::= <Version>

[Address (tunnel endpoint)]

[Message Counter]

9.9.3. Behavior

Regardless of local flow policy, a local address and port(s) MUST be

assigned to the host. If macro-flow based local policy is used, the

host is assigned an address and one or more ports. If micro-flow

based local policy is used, the host is assigned an address and

exactly one port.

If no remote flow policy is used, the RSIP gateway MUST use "don't

care" values for the remote address and ports parameters. If macro-

flow based remote policy is used, the remote address parameter MUST

contain the address specified in the associated request, and the

remote ports parameter must contain a "don't care" value. If micro-

flow based remote policy is used, the remote address and remote ports

parameters MUST contain the address and port information specified in

the associated request.

If the host detects an error or otherwise does not "understand" the

gateway's response, it SHOULD send a FREE_REQUEST with the bind ID

from the said ASSIGN_RESPONSE_RSAP-IP. This will serve to help

synchronize the states of the host and gateway.

The address of a tunnel endpoint that is not the RSIP gateway MAY be

specified. If this parameter is not specified, the RSIP gateway MUST

be assumed to be the tunnel endpoint.

9.10. EXTEND_REQUEST

9.10.1. Description

The EXTEND_REQUEST message is used to request a lease extension to a

current bind. It may be used with both RSA-IP and RSAP-IP. The host

MUST specify its client ID and the bind ID in question, and it MAY

suggest a lease time to the gateway.

9.10.2. Format

<EXTEND_REQUEST> ::= <Version>

[Lease Time]

[Message Counter]

9.10.3. Behavior

The following message-specific error conditions exist:

- If the host is not registered with the gateway, the gateway

MUST respond with an ERROR_RESPONSE containing the

REGISTER_FIRST error.

- If the message contains an incorrect client ID, the gateway

MUST respond with an ERROR_RESPONSE containing the

BAD_CLIENT_ID error.

- If the message contains an incorrect bind ID, the gateway MUST

respond with an ERROR_RESPONSE containing the BAD_BIND_ID

error.

If the RSIP gateway grants an extension to the host's lease, it MUST

RESPOND with an appropriate EXTEND_RESPONSE message. If the lease is

not renewed, the RSIP gateway MAY let it implicitly expire by doing

nothing or make it explicitly expire by sending an appropriate

FREE_RESPONSE message.

9.11. EXTEND_RESPONSE

9.11.1. Description

The EXTEND_RESPONSE message is used by an RSIP gateway to grant a

requested lease extension. The gateway MUST specify the client ID of

the host, the bind ID in question, and the new assigned lease time.

9.11.2. Format

<EXTEND_RESPONSE> ::= <Version>

[Message Counter]

9.11.3. Behavior

The RSIP gateway will determine lease time as per its local policy.

The returned time is to be interpreted as the number of seconds

before the lease expires, counting from the time at which the message

is sent/received.

9.12. FREE_REQUEST

9.12.1. Description

The FREE_REQUEST message is used by an RSIP host to free a binding.

The given bind ID identifies the bind to be freed. Resources may

only be freed using the granularity of a bind ID.

9.12.2. Format

<FREE_REQUEST> ::= <Version>

[Message Counter]

9.12.3. Behavior

The following message-specific error conditions exist:

- If the host is not registered with the gateway, the gateway

MUST respond with an ERROR_RESPONSE containing the

REGISTER_FIRST error.

- If the message contains an incorrect client ID, the gateway

MUST respond with an ERROR_RESPONSE containing the

BAD_CLIENT_ID error.

- If the message contains an incorrect bind ID, the gateway MUST

respond with an ERROR_RESPONSE containing the BAD_BIND_ID

error.

If a host receives an error in response to a FREE_REQUEST, this may

indicate that the host and gateway's states have become

unsynchronized. Therefore, the host SHOULD make an effort to

resynchronize, such as freeing resources then re-requesting them, or

de-registering then re-registering.

9.13. FREE_RESPONSE

9.13.1. Description

The FREE_RESPONSE message is used by an RSIP gateway to acknowledge a

FREE_REQUEST sent by an RSIP host, and to asynchronously deallocate

resources granted to an RSIP host.

9.13.2. Format

<FREE_RESPONSE> ::= <Version>

[Message Counter]

9.13.3. Behavior

An RSIP host must always be ready to accept a FREE_RESPONSE, even if

its lease on the specified bind ID is not yet expired.

9.14. QUERY_REQUEST

9.14.1. Description

A QUERY_REQUEST message is used by an RSIP host to ask an RSIP

gateway whether or not a particular address or network is local or

remote. The host uses this information to determine whether to

contact the host(s) directly (in the local case), or via RSIP (in the

remote case).

This message defines an indicator parameter with a 1-byte value field

and 2 defined values:

- 1 address

- 2 network

9.14.2. Format

<QUERY_REQUEST> ::= <Version>

[Message Counter]

[Address Tuple]...

[Network Tuple]...

where

9.14.3. Behavior

One or more address or network tuples may be specified. Each tuple

encodes a request regarding the locality (local or remote) of the

encoded address or network. If no tuple is specified, the RSIP

gateway should interpret the message as a request for all tuples that

it is willing to provide. Note that the FQDN form of the address

parameter cannot be used to specify the address of a network, and

only the netmask form of the address parameter can be used to specify

the netmask of a network.

If an RSIP gateway cannot determine whether a queried host or network

is local or remote, it SHOULD transmit a QUERY_RESPONSE with no

response specified for the said host or network.

The following message-specific error conditions exist:

- If the host is not registered with the gateway, the gateway

MUST respond with an ERROR_RESPONSE containing the

REGISTER_FIRST error.

- If the message contains an incorrect client ID, the gateway

MUST respond with an ERROR_RESPONSE containing the

BAD_CLIENT_ID error.

9.15. QUERY_RESPONSE

9.15.1. Description

A QUERY_RESPONSE message is used by an RSIP gateway to answer a

QUERY_REQUEST from an RSIP host.

This message defines an indicator parameter with a 1-byte value field

and 4 defined values:

- 1 local address

- 2 local network

- 3 remote address

- 4 remote network

9.15.2. Format

<QUERY_RESPONSE> ::= <Version>

[Message Counter]

[Local Address Tuple]...

[Local Network Tuple]...

[Remote Address Tuple]...

[Remote Network Tuple]...

where

9.15.3. Behavior

An RSIP gateway has some leeway in how it responds to a

QUERY_REQUEST. It may just provide the information requested, if it

can provide such information. It may provide its complete list of

address and networks, in order to minimize the number of requests

that the host needs to perform in the future. How an RSIP gateway

responds may depend on network traffic considerations as well.

If an RSIP gateway sends a QUERY_RESPONSE that does not contain any

tuples, or a QUERY_RESPONSE that does not contain a tuple that

applies to an associated tuple in the associated QUERY_REQUEST, this

should be interpreted that the RSIP gateway does not know whether the

queried host or network is local or remote. Appropriate host

behavior upon receipt of such a message is to assume that the queried

host or network is remote.

Note that an RSIP gateway is not expected to maintain a complete list

of all remote hosts and networks. In fact, a typical RSIP gateway

will only maintain a list of the networks and hosts that it knows are

local (private with respect to the RSIP host).

9.16. LISTEN_REQUEST

9.16.1. Description

A LISTEN_REQUEST message is sent by an RSIP host that wants to

must include its client ID, local address parameter and ports

parameters, and remote address and ports parameters. The client MAY

suggest a lease time and one or more tunnel types.

9.16.2. Format

<LISTEN_REQUEST> ::= <Version>

[Message Counter]

[Lease Time]

[Tunnel Type]...

9.16.3. Behavior

If the host wants to listen on a particular address or port, it may

specify these in the address and ports parameters. Otherwise it may

leave one or both of these parameters with "don't care" values.

If no remote flow policy is being used, the host MUST fill both the

remote address and ports parameters with "don't care" values. If

macro-flow based remote policy is used, the host MUST specify the

remote address, but MAY or MAY NOT specify the remote port(s). If

micro-flow based remote policy is used, the host MUST specify the

remote address and ports parameter.

Once a LISTEN_REQUEST has been granted, the RSIP gateway MUST forward

all packets destined to the address and port in question to the host,

even if the remote host address and port tuple has not been

previously contacted by the host.

LISTEN_REQUEST is not necessary for RSA-IP.

The following message-specific error conditions exist:

- If the host is not registered with the gateway, the gateway

MUST respond with an ERROR_RESPONSE containing the

REGISTER_FIRST error.

- If the message contains an incorrect client ID, the gateway

MUST respond with an ERROR_RESPONSE containing the

BAD_CLIENT_ID error.

- If the local address parameter is a don't care value and the

RSIP gateway cannot allocate ANY addresses, the RSIP gateway

MUST respond with an ERROR_RESPONSE containing the

LOCAL_ADDR_UNAVAILABLE error.

- If the local address parameter is not a don't care value there

are five possible error conditions:

o If the RSIP gateway cannot allocate ANY addresses, it MUST

respond with an ERROR_RESPONSE containing the

LOCAL_ADDR_UNAVAILABLE error.

o If the RSIP gateway cannot allocate the requested address

because it is in use, the RSIP gateway MUST respond with an

ERROR_RESPONSE containing the LOCAL_ADDR_INUSE error.

o If the RSIP gateway cannot allocate the requested address

because it is not allowed by policy, the RSIP gateway MUST

respond with an ERROR_RESPONSE containing the

LOCAL_ADDR_UNALLOWED error.

o If the RSIP gateway cannot allocate the requested address /

port tuple because it is in use, the RSIP gateway MUST

respond with an ERROR_RESPONSE containing the

LOCAL_ADDRPORT_INUSE error.

o If the RSIP gateway cannot allocate the requested address /

port tuple because it is not allowed by policy, the RSIP

gateway MUST respond with an ERROR_RESPONSE containing the

LOCAL_ADDRPORT_UNALLOWED error.

- If macro-flow based remote policy is used and the requested

remote address is not allowed by the RSIP gateway's policy, the

RSIP gateway MUST respond with an ERROR_RESPONSE containing the

REMOTE_ADDR_UNALLOWED error.

- If micro-flow based remote policy is used and the requested

remote address / port pair is not allowed by the RSIP gateway's

policy, the RSIP gateway MUST respond with an ERROR_RESPONSE

containing the REMOTE_ADDRPORT_UNALLOWED error.

- If an unsupported or unallowed tunnel type is specified, the

RSIP gateway MUST respond with an ERROR_RESPONSE containing the

BAD_TUNNEL_TYPE error.

- If the host has not specified local or remote address or port

information in enough detail, the RSIP gateway MUST respond

with an ERROR_RESPONSE containing the FLOW_POLICY_VIOLATION

error.

9.17. LISTEN_RESPONSE

9.17.1. Description

A LISTEN_RESPONSE message is used by an RSIP gateway to respond to a

LISTEN_REQUEST message from an RSIP host. The RSIP gateway MUST

issue a bind ID, and specify the address and port which have been

granted to the host. The gateway must also specify a tunnel type and

lease time.

If no remote flow policy is being used, the gateway MUST fill both

the remote address and ports parameters with "don't care" values. If

macro-flow based remote policy is used, the gateway MUST specify the

remote address, but MAY or MAY NOT specify the remote port(s). If

micro-flow based remote policy is used, the gateway MUST specify the

remote address and ports parameter.

9.17.2. Format

<LISTEN_RESPONSE> ::= <Version>

[Address (tunnel endpoint)]

[Message Counter]

9.17.3. Behavior

If no remote flow policy is being used, the gateway MUST fill both

the remote address and ports parameters with "don't care" values. If

macro-flow based remote policy is used, the gateway MUST specify the

remote address, but MAY or MAY NOT specify the remote port(s). If

micro-flow based remote policy is used, the gateway MUST specify the

remote address and ports parameter.

The address of a tunnel endpoint that is not the RSIP gateway MAY be

specified. If this parameter is not specified, the RSIP gateway MUST

be assumed to be the tunnel endpoint.

10. Discussion

10.1. Use of Message Counters, Timeouts, and Retransmissions

Message counters are conceptually similar to sequence numbers. They

are necessary to facilitate reliability when UDP is the transport

protocol. Each UDP message is marked with a message counter. When

such a message is transmitted, the message is stored in a "last

message" buffer. For RSIP hosts, a timer is set to expire at the

appropriate timeout value.

General rules:

- When an RSIP host transmits a message with a message counter

value of n, the RSIP gateway's response will contain a message

counter value of n.

- An RSIP host will not increment its message counter value to

n+1 until it receives a message from the RSIP gateway with a

message counter value of n.

- An RSIP gateway begins all sessions with a message counter

value of 1.

- If the message counter value reaches the maximum possible 32-

bit value, it will wrap around to 1, not 0.

- If a message with a message counter value of n is transmitted

by an RSIP host, but a timer expires before a response to that

message is received, the copy of the message (from the "last

message" buffer) is retransmitted.

- When an RSIP gateway receives a duplicate copy of a message

with a message counter value of n, it transmits the contents of

its "last message" buffer.

- When the RSIP gateway transmits an asynchronous RSIP message

(an RSIP message for which there was no request by the RSIP

host), a message counter value of 0 MUST be used. Note that

only three RSIP messages can be transmitted asynchronously:

ERROR_RESPONSE, DE-REGISTER_RESPONSE, and FREE_RESPONSE. These

messages may also be transmitted in response to an RSIP host

request, so their message counter values MAY be non-zero.

- If a message counter is not present in a message from an RSIP

host, but is required, the RSIP gateway MUST respond with an

ERROR_RESPONSE containing the MESSAGE_COUNTER_REQUIRED error.

10.2. RSIP Host and Gateway Failure Scenarios

When either the RSIP host or gateway suffers from an unrecoverable

failure, such as a crash, all RSIP-related state will be lost. In

this section, we describe the sequence of events that will occur in

both host and gateway failures, and how the host and gateway re-

synchronize.

10.2.1. Host Failure

After a host failure, the host will reboot and be unaware of any RSIP

state held on its behalf at the gateway.

If the host does not immediately attempt to re-establish a session,

it may receive RSIP packets on the RSIP client application port that

it was using before it rebooted. If an RSIP client application is

not active on this port, these packets will be responded to with ICMP

port unreachable messages. If TCP is the transport protocol, it is

likely that the connection will be terminated with a TCP RST. If an

RSIP client is active on this port, it will not recognize the session

that these packets belong to, and it SHOULD silently ignore them.

The RSIP host may also receive packets from a remote host with which

it was communicating before it rebooted. These packets will be

destined to the RSIP tunnel interface, which should not exist. Thus

they SHOULD be silently discarded by the RSIP host's stack, or the

RSIP host will transmit appropriate ICMP messages to the tunnel

endpoint (e.g., the RSIP gateway). The behavior of the system with

respect to sessions that were active before the reboot should be

similar to that of a publically addressable non-RSIP host that

reboots.

Upon rebooting, an RSIP host may attempt to establish a new RSIP

session with the RSIP gateway. Upon receiving the REGISTER_REQUEST

message, the RSIP gateway will be able to determine that, as far as

it is concerned, the RSIP host is already registered. Thus, it will

transmit an ERROR_RESPONSE with the ALREADY_REGISTERED message. Upon

receipt of this message, the RSIP host will know the client ID of its

old registration, and SHOULD immediately transmit a DE-

REGISTER_REQUEST using this client ID. After this is accomplished,

the states of the RSIP host and gateway have been synchronized, and a

new RSIP session may be established.

If the RSIP host does not de-register itself from the RSIP gateway,

it will eventually receive a DE-REGISTER_RESPONSE from the gateway,

when the gateway times out the host's session. Since the DE-

REGISTER_RESPONSE will refer to a client ID that has no meaning to

the host, the host SHOULD silently ignore such a message. At this

point, the states of the RSIP host and gateway have been

synchronized, and a new RSIP session may be established.

10.2.2. Gateway Failure

After a gateway failure, the gateway will reboot and be unaware of

any RSIP state held by an RSIP host.

Since the gateway will not attempt to contact any of its RSIP hosts,

a problem will first be detected when either an RSIP host sends an

RSIP message to the gateway, an RSIP host sends tunneled data to the

gateway, or data from a remote host intended for an RSIP host

arrives.

In the first case, the RSIP gateway SHOULD immediately response to

all messages (except for a REGISTER_REQUEST) with an ERROR_RESPONSE

with a REGISTER_FIRST error. Upon receipt of such a message, an RSIP

host MUST interpret the message as an indication of a loss of

synchronization between itself and the RSIP gateway. The RSIP host

SHOULD immediately transmit a DE-REGISTRATION_REQUEST with its old

client ID (which will generate another error, but this error SHOULD

be ignored by the host). At this point, the states of the RSIP host

and gateway have been synchronized, and a new RSIP session may be

established.

In the second case, all data that an RSIP host sends to the tunneled

interface of an RSIP server will either (1) be discarded silently,

(2) responded to with an ICMP Destination Unreachable message, such

as "Communication Administratively Prohibited", or (3) blindly routed

to the intended destination. In all of the above cases, the RSIP

gateway will not have an explicit method to notify the RSIP host of

the problem. To prevent a long term communications outage, small

lease times of several minutes can be set by the RSIP gateway.

In the third case, the RSIP gateway SHOULD discard all incoming

packets and/or respond with ICMP Port Unreachable messages.

10.3. General Gateway Policy

There is a significant amount of RSIP gateway policy that may be

implemented, but is beyond the scope of this document. We expect

that most of this policy will be site-specific or implementation-

specific and therefore do not make any recommendations. Examples of

general gateway policy include:

- How ports are allocated to RSIP hosts.

- Preferred length of lease times.

- How flow policy is applied to which hosts.

- How an RSIP gateway with multiple public IP addresses that may

be leased by RSIP clients determines how to partition

and/or lease these addresses.

10.4. Errors Not From the RSIP Protocol

Once an RSIP host and gateway have established a relationship and the

host is assigned resources to use, error may occur due to the host's

misuse of the resources or its attempting to use unassigned

resources. The following error behavior is defined:

- If a host attempts to use a local address which it has not been

allocated, the RSIP gateway MUST drop the associated packet(s)

and send the host an ERROR_RESPONSE containing the

LOCAL_ADDR_UNALLOWED error.

- If a host attempts to use a local address / port tuple which it

has not been allocated, the RSIP gateway MUST drop the

associated packet(s) and send the host an ERROR_RESPONSE

containing the LOCAL_ADDRPORT_UNALLOWED error.

- If a host attempts to contact a remote address which has not

been properly specified or otherwise approved (e.g., via an

ASSIGN_RESPONSE_RSAP-IP and macro or micro based remote flow

policy), the RSIP gateway MUST drop the associated packet(s)

and send the host an ERROR_RESPONSE containing the

REMOTE_ADDR_UNALLOWED error.

- If a host attempts to contact a remote address / port tuple

which has not been properly specified or otherwise approved

(e.g., via an ASSIGN_RESPONSE_RSAP-IP and micro based remote

flow policy), the RSIP gateway MUST drop the associated

packet(s) and send the host an ERROR_RESPONSE containing the

REMOTE_ADDRPORT_UNALLOWED error.

- If a host attempts to establish or use an improper tunnel type,

the RSIP gateway MUST respond with an ERROR_RESPONSE containing

the BAD_TUNNEL_TYPE error.

- If the RSIP gateway's detects a local fault which prevents its

RSIP server module from continuing operation, the RSIP gateway

MUST respond with an ERROR_RESPONSE containing the

INTERNAL_SERVER_ERROR error.

10.5. Address and Port Requests and Allocation

Regardless of local flow policy, an RSIP host may "suggest" that it

would like to use a particular local address and/or port number in a

particular binding. An RSIP gateway that cannot grant such a

request, because the specified resources are already in use, MUST

respond with an ERROR_RESPONSE containing the LOCAL_ADDR_INUSE or

LOCAL_ADDRPORT_INUSE values.

10.6. Local Gateways and Flow Policy Interaction

An RSIP host may initialize a publically accessible gateway (such as

an FTP or HTTP gateway) by transmitting a LISTEN_REQUEST message to

an RSIP gateway and receiving a LISTEN_RESPONSE. However, unless no

remote flow policy is used, the gateway will have to specify the

address or address and port of a single remote host that will be

allowed to contact it. Obviously, such as restriction is not very

useful for hosts that require their gateways to be accessible by any

remote host.

This indicates that there is a conflict between flow-based policy and

support for gateways. The main purpose of enforcing flow-based

policy for LISTEN_REQUESTs is that it allows an RSIP gateway tight

control over how an RSIP host uses ports and the associated

accounting. For example, an RSIP host, operating under remote

micro-flow based policy and using a protocol such as FTP, will have

to specify the address and port that it will receive FTP data on, as

well as the address and port that the gateway will transmit data

from, in a LISTEN_REQUEST.

In general, an RSIP gateway may not allow arbitrary hosts to start

public gateways because of the traffic and security concerns. Thus,

we recommend that if remote micro-flow based policy is used, that an

RSIP gateway only allow public gateways on RSIP hosts via

administrative override.

Currently, RSIP hosts can only be identified by their local IP

address or MAC address.

11. Security Considerations

RSIP, in and of itself, does not provide security. It may provide

the illusion of security or privacy by hiding a private address

space, but security can only be ensured by the proper use of security

protocols and cryptographic techniques.

An RSIP gateway should take all measures deemed necessary to prevent

its hosts from performing intentional or unintentional denial-of-

service attacks by request large sets of resources.

Currently, RSIP hosts can only be identified by their local IP

address or, in some cases, MAC address. It is desirable to allow

RSIP messages sent between a host and gateway to be authenticated.

Further discussion of such authentication can be found in [RSIP-

FRAME].

Discussion of RSIP support for end-to-end IPsec can be found in

[RSIP-IPSEC].

12. IANA Considerations

All of the designations below have been registered by the IANA.

- RSIP port number: 4555

- RSIP error codes (see Appendix A).

- RSIP message type codes (see Appendix B).

- RSIP tunnel types, methods, and flow policies.

RSIP parameter values are designated as follows:

- 0 Reserved

- 1-240 Assigned by IANA

- 241-255 Reserved for private use

New registrations for the above namespaces are recommended to be

allocated via the Specification Required method documented in

[RFC2434].

13. Acknowledgements

The authors would like to specifically thank Gabriel Montenegro, Pyda

Srisuresh, Brian Carpenter, Eliot Lear, Dan Nessett, Gary Jaszewski,

Naveen Rajanikantha, Sudhakar Ramakrishna, Jim March, and Rick Cobb

for their input. The IETF NAT working group as a whole has been

extremely helpful in the ongoing development of RSIP.

14. Appendix A: RSIP Error Numbers

This section provides descriptions for the error values in the RSIP

error parameter.

All errors are grouped into the following categories:

100's: General errors.

101: UNKNOWN_ERROR. An error that cannot be identified has

occurred. This error should be used when all other error

messages are inappropriate.

102: USE_TCP. A host has attempted to use UDP on a server that

only supports TCP.

103: FLOW_POLICY_VIOLATION: A host has not specified address or

port information in enough detail for its assigned flow policy.

104: INTERNAL_SERVER_ERROR: An RSIP server application has

detected an unrecoverable error within itself or the RSIP

gateway.

105: MESSAGE_COUNTER_REQUIRED: An RSIP host did not use a message

counter parameter in a situation in which it should have.

106: UNSUPPORTED_RSIP_VERSION: An RSIP host sent a message with a

version number that is not supported by the RSIP gateway.

200's: Parameter and message errors. The gateway uses these errors

when it detects that a parameter or message is malformed, as well

as when it does not understand a parameter or message.

201: MISSING_PARAM. The request does not contain a required

parameter.

202: DUPLICATE_PARAM. The request contains an illegal duplicate

parameter.

203: EXTRA_PARAM. The request contains a parameter that it should

not.

204: ILLEGAL_PARAM. The gateway does not understand a parameter

type.

205: BAD_PARAM. A parameter is malformed.

206: ILLEGAL_MESSAGE. The gateway does not understand the message

type. The message type is neither mandatory nor optional.

207: BAD_MESSAGE. A message is malformed and gateway parsing

failed.

208: UNSUPPORTED_MESSAGE: The host has transmitted an optional

message that the gateway does not support.

300's: Permission, resource, and policy errors. The gateway uses

these errors when a host has attempted to do something that it is

not permitted to do, or something that violated gateway policy.

301: REGISTER_FIRST. The RSIP host has attempted to request or

use resources without registering.

302: ALREADY_REGISTERED. The host has attempted to register again

without first de-registering.

303: ALREADY_UNREGISTERED. The host has attempted to de-register

but it is already in the unregistered state.

304: REGISTRATION_DENIED. The gateway will not allow the host to

305: BAD_CLIENT_ID. The host has referred to itself with the

wrong client ID.

306: BAD_BIND_ID. The request refers to a bind ID that is not

valid for the host.

307: BAD_TUNNEL_TYPE. The request refers to a tunnel type that is

not valid for the host.

308: LOCAL_ADDR_UNAVAILABLE. The gateway is currently not able to

allocate ANY local address, but the host may try again later.

309: LOCAL_ADDRPORT_UNAVAILABLE. The gateway is currently not

able to allocate ANY local IP address / port tuple of the

requested magnitude (i.e., number of ports), but the host may

try again later.

310: LOCAL_ADDR_INUSE. The gateway was not able to allocate the

requested local address because it is currently used by another

entity.

311: LOCAL_ADDRPORT_INUSE. The gateway was not able to allocate

the requested local address / port tuple because it is

currently used by another entity.

312: LOCAL_ADDR_UNALLOWED. The gateway will not let the host use

the specified local IP address due to policy.

313: LOCAL_ADDRPORT_UNALLOWED. The gateway will not let the host

use the specified local address / port pair due to policy.

314: REMOTE_ADDR_UNALLOWED. The gateway will not allow the host

to establish a session to the specified remote address.

315: REMOTE_ADDRPORT_UNALLOWED. The gateway will not allow the

host to establish a session to the specified remote address /

port tuple.

400's: IPsec errors. All errors specific to RSIP / IPsec operation.

See [RSIP-IPSEC].

15. Appendix B: Message Types

This section defines the values assigned to RSIP message types. We

also indicate which RSIP entity, host or gateway, produces each

messages, and whether it is mandatory or optional. All *_REQUEST

messages are only to be implemented on hosts, while all *_RESPONSE

messages are only to be implemented on gateways. RSIP

implementations (both host and gateway) MUST support all mandatory

messages in order to be considered "RSIP compliant".

Value Message Implementation Status

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

1 ERROR_RESPONSE gateway mandatory

2 REGISTER_REQUEST host mandatory

3 REGISTER_RESPONSE gateway mandatory

4 DE-REGISTER_REQUEST host mandatory

5 DE-REGISTER_RESPONSE gateway mandatory

6 ASSIGN_REQUEST_RSA-IP host optional

7 ASSIGN_RESPONSE_RSA-IP gateway optional

8 ASSIGN_REQUEST_RSAP-IP host mandatory

9 ASSIGN_RESPONSE_RSAP-IP gateway mandatory

10 EXTEND_REQUEST host mandatory

11 EXTEND_RESPONSE gateway mandatory

12 FREE_REQUEST host mandatory

13 FREE_RESPONSE gateway mandatory

14 QUERY_REQUEST host optional

15 QUERY_RESPONSE gateway mandatory

16 LISTEN_REQUEST host optional

17 LISTEN_RESPONSE gateway optional

16. Appendix C: Example RSIP host/gateway transactions

In this appendix, we present an exemplary series of annotated

transactions between an RSIP host and an RSIP gateway. All host to

gateway traffic is denote by `C --> S' and all gateway to host

traffic is denoted by `S --> C'. Parameter values are denoted inside

of parentheses. Versions, message types, and overall lengths are not

included in order to save space. "Don't care" values are indicated

by 0's.

A ports parameter is represented by the number of ports followed by

the port numbers, separated by dashes. For example, 2-1012-1013

indicates two ports, namely 1012 and 1013, while 16-10000 indicates

16 ports, namely 10000-10015, and 4-0 indicates four ports, but the

sender doesn't care where they are.

IPv4 addresses are assumed.

16.1. RSAP-IP with Local Macro-flow Based Policy and No Remote Flow

Policy

This example exhibits the loosest policy framework for RSAP-IP.

C --> S: REGISTER_REQUEST ()

The host attempts to register with the gateway.

S --> C: REGISTER_RESPONSE (Client ID = 1, Local Flow Policy =

Macro, Remote Flow policy = None, Lease Time = 600)

The gateway responds, assigning a Client ID of 1, local macro-

flow based policy and no remote flow policy. No RSIP method is

indicated, so RSAP-IP is assumed. No tunnel type is indicated,

so IP-IP is assumed. A lease time of 600 seconds is assigned.

C --> S: ASSIGN_REQUEST_RSAP-IP: (Client ID = 1, Address (local) =

0, Ports (local) = 4-0, Address (remote) = 0, Ports (remote) =

0, Lease Time = 3600)

The host requests an address and four ports to use with it, but

doesn't care which address or ports are assigned. The host

does not specify the remote address or ports either. The host

suggests a lease time of 3600 seconds.

S --> C: ASSIGN_RESPONSE_RSAP-IP: (Client ID = 1, Bind ID = 1,

Address (local) = 149.112.240.156, Ports (local) = 4-1234,

Address (remote) = 0, Ports (remote) = 0, Lease Time = 1800,

Tunnel Type = IP-IP)

The gateway responds by indicating that a bind ID of 1 has been

assigned to IP address 149.112.240.156 with ports 1234-1237.

Any remote host may be communicated with, using any remote port

number. The lease time has been assigned to be 1800 seconds,

and the tunnel type is confirmed to be IP-IP.

The host is now able to communicate with any host on the public

network using these resources.

C --> S: QUERY_REQUEST: (Client ID = 1, Indicator = network,

Address (network) = 10.20.60.0, Address (netmask)

255.255.255.0)

The host asks the gateway if the network 10.20.60.0/24 is

local.

S --> C: QUERY_RESPONSE: (Client ID = 1, Indicator = network,

Address (network) = 10.20.60.0, Address (netmask) =

255.255.255.0)

The gateway responds indicating that the network in question is

local.

C --> S: ASSIGN_REQUEST_RSAP-IP: (Client ID = 1, Address (local) =

149.112.240.156, Ports (local) = 8-1238, Address (remote) = 0,

Ports (remote) = 0, Lease Time = 1800)

The host requests eight more particular ports for use with

RSAP-IP with the same address. A lease of 1800 seconds is

requested. IP-IP tunneling is implied by default.

S --> C: ASSIGN_RESPONSE_RSAP-IP: (Client ID = 1, Bind ID = 2,

Address (local) = 149.112.240.156, Ports (local) = 8-1305,

Address (remote) = 0, Ports (remote) = 0, Lease Time = 1800)

The gateway grants the request with the same address, but with

a different set of ports. IP-IP tunneling is implied by

default.

C --> S: FREE_REQUEST (Client ID = 1, Bind ID = 1)

The host frees bind ID 1; i.e., ports 1234-1237 from IP address

149.112.240.156. Note that the address itself is still

assigned to the host because the host is still assigned ports

1305-1314.

S --> C: FREE_RESPONSE (Client ID = 1, Bind ID = 1)

The gateway acknowledges that Bind ID 1 has been freed.

C --> S: EXTEND_REQUEST (Client ID = 1, Bind ID = 2, Lease Time =

1800)

The host request that the lease on bind ID 1 be extended for

1800 seconds.

S --> C: EXTEND_RESPONSE (Client ID = 1, Bind ID = 2, Lease Time =

1800)

The gateway confirms the request.

S --> C: FREE_RESPONSE (Client ID = 1, Bind ID = 2)

The gateway forces the host to free the resources of bind ID 2.

C --> S: DE-REGISTER_REQUEST (Client ID = 1)

The host de-registers with the sever.

S --> C: DE-REGISTER_RESPONSE (Client ID = 1)

The gateway acknowledges that the host has de-registered.

16.2. RSAP-IP with Local Micro-flow Based Policy and Remote Micro-

flow Based Policy

This example exhibits the strictest policy framework for RSAP-IP.

C --> S: REGISTER_REQUEST ()

The host attempts to register with the gateway.

S --> C: REGISTER_RESPONSE (Client ID = 5, Local Flow Policy =

Micro, Remote Flow policy = Micro, RSIP Method = RSAP-IP, RSIP

Method = RSA-IP, Tunnel Type = IP-IP, Tunnel Type = GRE, Lease

Time = 600)

The gateway responds, assigning a Client ID of 5, local micro-

flow based policy and remote micro-flow based policy. Both

RSAP-IP and RSA-IP are supported. Both IP-IP and GRE tunnel

types are supported. A lease time of 600 seconds is assigned.

C --> S: ASSIGN_REQUEST_RSAP-IP: (Client ID = 5, Address (local) =

0, Ports (local) = 0, Address (remote) = 38.196.73.6, Ports

(remote) = 21, Lease Time = 600, Tunnel Type = IP-IP)

The host requests a local address and a port assignment to use

with it. The host indicates that it wants to contact host

38.196.73.6 at port 21 (FTP control). The host requests a

lease time of 600 seconds and a tunnel type of IP-IP.

S --> C: ASSIGN_RESPONSE_RSAP-IP: (Client ID = 5, Bind ID = 1,

Address (local) = 149.112.240.156, Ports (local) = 2049,

Address (remote) = 38.196.73.6, Ports (remote) = 21, Lease Time

= 600, Tunnel Type = IP-IP)

The gateway responds by indicating that a bind ID of 1 has been

assigned to IP address 149.112.240.156 with port 2049. Only

host 38.196.73.6 at port 21 may be contacted. The lease time

has been assigned to be 600 seconds, and the tunnel type is

confirmed to be IP-IP.

C --> S: LISTEN_REQUEST: (Client ID = 5, Address (local) =

149.112.240.156, Ports (local) = 2050, Address (remote) =

38.196.73.6, Ports (remote) = 20)

The host requests a listen port 2050 at the same address that

it has been assigned. Only host 38.196.73.6 from ports 20 (FTP

data) will be able to contact it.

S --> C: LISTEN_RESPONSE: (Client ID = 5, Address (local) =

149.112.240.156, Ports (local) = 2050, Address (remote) =

38.196.73.6, Ports (remote) = 20, Lease Time = 600, Tunnel Type

= IP-IP)

The gateway confirms the request and assigns a lease time of

600 seconds and a tunnel type of IP-IP.

C --> S: DE-REGISTER_REQUEST (Client ID = 5)

The host de-registers with the sever.

S --> C: DE-REGISTER_RESPONSE (Client ID = 5)

The gateway acknowledges that the host has de-registered. All

of the host's bindings have been implicitly revoked.

16.3. RSA-IP with Local Macro-flow Based Policy and Remote Macro-

flow based Policy

This example exhibits a medium level of control for RSA-IP.

C --> S: REGISTER_REQUEST ()

The host attempts to register with the gateway.

S --> C: REGISTER_RESPONSE (Client ID = 3, Local Flow Policy =

Macro, Remote Flow policy = Macro, RSIP Method = RSAP-IP, RSIP

Method = RSA-IP, Tunnel Type = IP-IP, Tunnel Type = L2TP, Lease

Time = 600)

The gateway responds, assigning a Client ID of 3, local macro-

flow based policy and remote macro-flow based policy. Both

RSAP-IP and RSA-IP are supported. Both IP-IP and L2TP tunnel

types are supported. A lease time of 600 seconds is assigned.

C --> S: ASSIGN_REQUEST_RSA-IP: (Client ID = 3, Address (local) =

0, Address (remote) = www.foo.com, Ports (remote) = 0, Lease

Time = 3600, Tunnel Type = IP-IP)

The host requests a local address and indicates that it wants

to contact host www.foo.com.

S --> C: ERROR_RESPONSE: (Error = REMOTE_ADDR_UNALLOWED, Client ID

= 3)

The gateway indicates that the host is not permitted to

establish communication with www.foo.com.

C --> S: ASSIGN_REQUEST_RSA-IP: (Client ID = 3, Address (local) =

0, Address (remote) = www.bar.com, Ports (remote) = 0, Lease

Time = 3600, Tunnel Type = IP-IP)

The host requests a local address and indicates that it wants

to contact host www.bar.com.

S --> C: ASSIGN_RESPONSE_RSA-IP: (Client ID = 3, Bind ID = 1,

Address (local) = 149.112.240.17, Address (remote) =

www.bar.com, Ports (remote) = 0, Lease Time = 3600, Tunnel Type

= IP-IP)

The gateway responds by granting local IP address

149.112.240.17 to the host, and permitting it to communicate

with www.bar.com, at any port. Requested lease time and tunnel

type are also granted.

C --> S: DE-REGISTER_REQUEST (Client ID = 3)

The host de-registers with the sever.

S --> C: DE-REGISTER_RESPONSE (Client ID = 3)

The gateway acknowledges that the host has de-registered. All

of the host's bindings have been implicitly revoked.

17. Appendix D: Example RSIP host state diagram

This appendix provides an exemplary diagram of RSIP host state. The

host begins in the unregistered state. We assume that for UDP, if a

message is lost, the host will timeout and retransmit another copy of

it. We recommend a 7-fold binary exponential backoff timer for

retransmissions, with the first timeout occurring after 12.5 ms.

This diagram does not include transitions for the LISTEN_REQUEST

message.

send

REGISTER_REQUEST

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

------------->Registration<-- timeout/send

+--->Unregistered<------------- Pending --- REGISTER_REQUEST

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

+------------+ 7th timeout/recv

^ ERROR_RESPONSE

7th timeout/recv recv timeout/send

DE-REGISTER_RESPONSE REGISTER_RESPONSE QUERY_REQUEST

send

send DE- v QUERY_REQUEST

+----------------+ REGISTER_REQUEST+----------+ +----------+

Registered <---------------- --------->Registered

De-registration Registered Query

Pending ----------------> <--------- Pending

+----------------+ recv +----------+ +----------+

^ ERROR_RESPONSE ^ 7th timeout/recv

QUERY_RESPONSE or

timeout/send ERROR_RESPONSE

DE-REGISTER_REQUEST 7th timeout/recv

ERROR_RESPONSE

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

Go to Registered send

+----------------+ ASSIGN_REQUEST

^ timeout/send

Yes FREE_REQUEST

+ + v v

+ + 7th timeout/ +--------+ +----------+

+ Are all + recv Free Assignment<--timeout/send

+ resources +<-----------Pending Pending ---ASSIGN_REQUEST

+ freed? + FREE_RESPONSE+--------+ +----------+

+ + ^

+ +

+ recv

No send recv ASSIGN_RESPONSE

v ERROR_REQUEST ERROR_

+---------------+ RESPONSE

Go to Assigned 7th timeout/recv

+---------------+ QUERY_RESPONSE or

recv ERROR_RESPONSE

+---------------+ERROR_RESPONSE v v +-----------+

Assigned -------------->+-------------+--------> Assigned

+>De-registration Assigned Query

Pending <--------------+-------------+<-------- Pending

+---------------+ send ^ +-----------+

^ DE-REGISTER_REQUEST send ^

QUERY_REQUEST

timeout/send 7th/timeout/recv send

DE-REGISTER_ ASSIGN_RESPONSE ASSIGN_REQUEST timeout/send

REQUEST or ERROR_RESPONSE QUERY_REQUEST

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

Assigned

Assignment

Pending

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

timeout/send

ASSIGN_REQUEST

18. References

[RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot,

G.J. and E. Lear, "Address Allocation for Private

Internets", BCP 5, RFC1918, February 1996.

[RFC2119] Bradner, S., "Key words for use in RFCs to indicate

requirement levels", BCP 14, RFC2119, March 1997.

[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an

IANA Considerations Section in RFCs", BCP 26, RFC2434,

October 1998.

[RFC2663] Srisuresh, P. and M. Holdrege, "IP Network Address

Translator (NAT) Terminology and Considerations", RFC

2663, August 1999.

[RSIP-FRAME] Borella, M. Lo, J., Grabelsky, D. and G. Montenegro,

"Realm Specific IP: Framework", RFC3102, October 2001.

[RSIP-IPSEC] Montenegro, G. and M. Borella, "RSIP Support for End-

to-end IPSEC", RFC3104, October 2001.

19. Authors' Addresses

Michael Borella

CommWorks

3800 Golf Rd.

Rolling Meadows IL 60008

Phone: (847) 262-3083

EMail: mike_borella@commworks.com

David Grabelsky

CommWorks

3800 Golf Rd.

Rolling Meadows IL 60008

Phone: (847) 222-2483

EMail: david_grabelsky@commworks.com

Jeffrey Lo

Candlestick Networks, Inc

70 Las Colinas Lane,

San Jose, CA 95119

Phone: (408) 284 4132

EMail: yidarlo@yahoo.com

Kunihiro Taniguchi

NEC USA

C&C Research Labs.

110 Rio Robles

San Jose, CA 95134

Phone: (408) 943-3031

EMail: taniguti@ccrl.sj.nec.com

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