Network Working Group R. Rockell
Request for Comments: 2772 Sprint
Obsoletes: 2546 R. Fink
Category: Informational ESnet
February 2000
6Bone Backbone Routing Guidelines
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2000). All Rights Reserved.
Abstract
The 6Bone is an Ipv6 testbed to assist in the evolution and
deployment of IPv6. Because of this, it is important that the core
backbone of the IPv6 network maintain stability, and that all
operators have a common set of rules and guidelines by which to
deploy IPv6 routing equipment.
This document provides a set of guidelines for all 6bone routing
equipment operators to use as a reference for efficient and stable
deployment of 6bone routing systems. As the complexity of the 6Bone
grows,the adherence to a common set of rules becomes increasingly
important in order for an efficient, scalable backbone to exist.
Table of Contents
1. IntrodUCtion.................................................. 2
2. Scope of this document........................................ 3
3. Common Rules for the 6bone.................................... 3
3.1 Link-local prefixes...................................... 3
3.2 Site-local prefixes...................................... 4
3.3 Loopback and unspecified prefixes........................ 5
3.4 Multicast prefixes....................................... 5
3.5 IPv4 compatible prefixes................................. 5
3.6 IPv4-mapped prefixes..................................... 6
3.7 Default routes........................................... 6
3.8 Yet undefined unicast prefixes........................... 6
3.9 Inter-site links......................................... 6
3.10 6to4 Prefixes........................................... 7
3.11 Aggregation & advertisement issues...................... 7
4. Routing Policies for the 6bone................................ 7
5. The 6Bone Registry............................................ 8
6. Guidelines for new sites joining the 6Bone.................... 9
7. Guidelines for 6Bone pTLA sites............................... 9
8. 6Bone Operations group........................................ 11
9. Common rules enforcement for the 6bone........................ 11
10. Security Considerations...................................... 12
11. References................................................... 12
12. Authors' Addresses........................................... 13
13. Full Copyright Statement..................................... 14
1. Introduction
The 6Bone is an IPv6 testbed to assist in the evolution and
deployment of IPv6. Because of this, it is important that the core
backbone of the IPv6 network maintain stability, and that all
operators have a common set of rules and guidelines by which to
deploy IPv6 routing equipment.
This document provides a set of guidelines for all 6bone routing
equipment operators to use as a reference for efficient and stable
deployment of 6bone routing systems. As the complexity of the 6Bone
grows,the adherence to a common set of rules becomes increasingly
important in order for an efficient, scalable backbone to exist.
This document uses BGP-4 with Multiprotocol Extensions for BGP-4 as
defined [RFC2283], commonly referred to as BGP4+, as the currently
accepted EGP.
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].
2. Scope of this document
This document is a best-practices Informational document aimed at
IPv6 entities which operate under the 6Bone IPv6 testbed TLA
allocation.
3. Common Rules for the 6bone
This section details common rules governing the routing of the 6Bone.
They are derived from the issues encountered on the 6Bone, with
respect to the routes advertised, handling of special addresses, and
aggregation:
1) link local prefixes
2) site local prefixes
3) loopback and unspecified prefixes
4) multicast prefixes
5) IPv4-compatible prefixes
6) IPv4-mapped prefixes
7) default routes
8) yet undefined unicast prefixes (from a different /3 prefix)
9) inter-site links issues
10) 6to4 prefixes
11) aggregation & advertisement issues
3.1 Link-local prefixes
This link-local prefix (FE80::/10) MUST NOT be advertised through
either an IGP or an EGP. Under no circumstance should this prefix be
seen in the 6Bone backbone routing table.
By definition, the link-local prefix has a scope limited to a
specific link. Since the prefix is the same on all IPv6 links,
advertising it in any routing protocol does not make sense and,
worse, may introduce nasty error conditions.
Well known cases where link-local prefixes could be advertised by
mistake include, but are not limited to:
- a router advertising all directly connected network prefixes
including the link-local one
- subnetting of the link-local prefix
In such cases, vendors should be urged to correct their code. While
vendors should be encouraged to fix the problem, the ultimate
responsibility lies on the operator of that IPv6 site to correct the
problem through whatever means necessary.
Should a pTLA discover link-local prefixes coming from another pTLA,
it is the responsibility of the pTLA leaking the routes to filter
these, and correct the problem in a timely fashion. Should a pTLA
discover that a downstream of that pTLA is leaking link-local
prefixes, it is the pTLA's responsibility to ensure that these
prefixes are not leaked to other pTLA's, or to other downstreams of
that pTLA.
Failure to filter such routes in a timely fashion may result in the
manual shutting down of BGP4+ sessions to that pTLA, from other
pTLA's.
(Also, it is each pTLA, pNLA, and end-site's responsibility to not
only filter their own BGP4+ sessions appropriately to peers, but to
filter routes coming from peers as well, and to only allow those
routes that fit the aggregation model, and do not cause operational
problems).
3.2 Site-local prefixes
Site local prefixes (in the FEC0::/10 range) MAY be advertised by
IGP's or EGP's within a site. The precise definition of a site is
ongoing work of the IPng working group, but should generally include
a group of nodes that are operating under one administrator or group
of administrators, or a group of nodes which are used for a common
purpose.
Site-local prefixes MUST NOT be advertised across transit pNLAs,
pTLAs, or leaf-sites.
Again, should site-local prefixes be leaked outside of a given site,
it is the responsibility of the site to fix the problem in a timely
manner, either through filters, or via other means which remove the
operational impact that those prefixes had on the peering sites
involved. However, every site SHOULD filter not only outbound on
their EGP, but also inbound, in order to ensure proper routing
announcements are not only sent, but also received.
3.3 Loopback and unspecified prefixes
The loopback prefix (::1/128) and the unspecified prefix (::0/128)
MUST NOT be advertised by any routing protocol.
The same responsibility lies with the party guilty of advertising the
loopback or unspecified prefix as in Section 3.1 and 3.2.
3.4 Multicast prefixes
Multicast prefixes MUST NOT be advertised by any unicast routing
protocol. Multicast routing protocols are designed to respect the
semantics of multicast and MUST therefore be used to route packets
with multicast destination addresses (in the range of FF00::/8).
Multicast address scopes MUST be respected on the 6Bone. Only global
scope multicast addresses MAY be routed across transit pNLAs and
pTLAs. There is no requirement on a pTLA to route multicast packets
at the time of the writing of this memo.
Organization-local multicasts (in the FF08::/16 or FF18::/16 ranges)
MAY be routed across a pNLA to its leaf sites.
Site-local multicasts MUST NOT be routed toward transit pNLAs or
pTLAs.
Link-local multicasts and node-local multicasts MUST NOT be routed at
all.
3.5 IPv4 compatible prefixes
Sites may choose to use IPv4 compatible addresses (::a.b.c.d where
a.b.c.d represents the octets of an IPv4 address) internally. As
there is no real rationale today for doing so, these address SHOULD
NOT be used or routed in the 6Bone.
The ::/96 IPv4-compatible prefixes MAY be advertised by IGPs.
IPv4 compatible prefixes MUST NOT be advertised by EGPs to transit
pNLAs or pTLAs.
Should ::/96 IPv4-compatible prefixes be leaked into an EGP, it is
the responsibility of the party who is advertising the route to fix
the problem, either through proper filters, or through other means,
while it remains in the best interest of all particiapants of the
6Bone to filter both outbound and inbound at their IGP borders.
3.6 IPv4-mapped prefixes
IPv4-mapped prefixes (::FFFF:a.b.c.d where a.b.c.d represents the
octets of an IPv4 address) MAY be advertised by IGPs within a site.
It may be useful for some IPv6 only nodes within a site to have such
a route pointing to a translation device, to aid in deployment of
IPv6.
IPv4-mapped prefixes MUST NOT be advertised by EGPs.
3.7 Default routes
6Bone core pTLA routers MUST be default-free.
pTLAs MAY advertise a default route to any downstream peer (non-pTLA
site). Transit pNLAs MAY advertise a default route to any of their
downstreams (other transit pNLA or leaf site).
Should a default route be redistributed into an EGP and found on any
pTLA EGP sessions, it is the responsibility of the pTLA to fix this
problem immediately upon realization of the route's existence, and
the responsibility of the guilty pTLA to push the entity from which
the default route was originated, should the default route have
originated from downstream of a pTLA.
3.8 Yet undefined unicast prefixes
Yet undefined unicast prefixes from a format prefix other than
2000::/3 MUST NOT be advertised by any routing protocol in the 6Bone.
In particular, RFC2471 test addresses MUST NOT be advertised on the
6Bone.
Routing of global unicast prefixes outside the 6Bone range
(3ffe::/16), and routing of global unicast prefixes yet undelegated
in the range (3ffe::/16) are discussed in section 4, Routing
policies, below.
3.9 Inter-site links
Global IPv6 addresses must be used for the end points of inter-site
links. In particular, IPv4 compatible addresses MUST NOT be used for
tunnels.
Sites MAY use Other addressing schemes for Inter-site links, but
these addresses MUST NOT be advertised into the IPv6 global routing
table.
Prefixes for inter-site links MUST NOT be injected in the global
routing tables.
3.10 6to4 Prefixes
The 6to4 prefix, or some portion thereof, MAY be announced by any
pTLA which has a current implementation of 6to4 in their IPv6
network. However, as 6to4 implementors gain more operational
eXPerience, it MAY be necessary to change this in some way. At the
time of the writing of this docuement, any pTLA MAY announce the 6to4
prefix into global EBGP. However, in order to announce this block,
the pTLA MUST have a 6to4 router active, sourcing this prefix
announcement.
This section subject to change, and MAY vary, depending on 6to4
progress within the NGTRANS working group.
3.11 Aggregation & advertisement issues
Route aggregation MUST be performed by any border router talking EGP
with any other IPv6 sites. More-specifics MUST NOT be leaked into or
across the IPv6 6Bone backbone.
4. Routing Policies for the 6bone
Leaf sites or pNLAs MUST only advertise to an upstream provider the
prefixes assigned by that provider. Advertising a prefix assigned by
another provider to a provider is not acceptable, and breaks the
aggregation model. A site MUST NOT advertise a prefix from another
provider to a provider as a way around the multi-homing problem.
However, in the interest of testing new solutions, one may break this
policy, so long as ALL affected parties are aware of this test, and
all agree to support this testing. These policy breaks MUST NOT
affect the 6bone routing table globally.
To clarify, if one has two upstream pNLA or pTLA providers, (A and B
for this example), one MUST only announce the prefix delegated to one
by provider A to provider A, and one MUST only announce the prefeix
delegated by one from provider B upstream to provider B. There exists
no circumstance where this should be violated, as it breaks the
aggregation model, and could globally affect routing decisions if
downstreams are able to leak other providers' more specific
delegations up to a pTLA. As the IPNG working group works through the
multi-homing problem, there may be a need to alter this rule
slightly, to test new strategies for deployment. However, in the case
of current specifications at the time of this writing, there is no
reason to advertise more specifics, and pTLA's MUST adhere to the
current aggregation model.
Site border routers for pNLA or leaf sites MUST NOT advertise
prefixes more specific (longer) than the prefix that was allocated by
their upstream provider.
All 6bone pTLAs MUST NOT advertise prefixes longer than a given pTLA
delegation (currently /24 or /28) to other 6bone pTLAs unless special
peering arrangements are implemented. When such special peering
aggreements are in place between any two or more 6bone pTLAs, care
MUST be taken not to leak the more specifics to other 6bone pTLAs not
participating in the peering aggreement. 6bone pTLAs which have such
agreements in place MUST NOT advertise other 6bone pTLA more
specifics to downstream 6bone pNLAs or leaf sites, as this will break
the best-path routing decision.
The peering agreements across the 6Bone may be by nature non-
commercial, and therefore MAY allow transit traffic, if peering
agreements of this nature are made. However, no pTLA is REQUIRED to
give or receive transit service from another pTLA.
Eventually, the Internet registries will assign prefixes under other
than the 6Bone TLA (3FFE::/16). As of the time this document was
written in 1999, the Internet registries were starting to assign /35
sub-TLA (sTLA) blocks from the 2001::/16 TLA. Others will certainly
be used in the future.
The organizations receiving prefixes under these newer TLAs would be
expected to want to establish peering and connectivity relationships
with other IPv6 networks, both in the newer TLA space and in the
6bone pTLA space. Peering between new TLA's and the current 6Bone
pTLA's MAY occur, and details such as transit, and what routes are
received by each, are outside of general peering rules as stated in
this memo, and are left up to the members of those TLA's and pTLA's
that are establishing said peerings. However, it is expected that
most of the rules discussed here are equally applicable to new TLAs.
5. The 6Bone Registry
The 6Bone registry is a RIPE-181 database with IPv6 extensions used
to store information about the 6Bone, and its sites. The 6bone is
Accessible at:
<http://www.6bone.net/whois.Html>)
Each 6Bone site MUST maintain the relevant entries in the 6Bone
registry. In particular, the following object MUST be present for all
6Bone leaf sites, pNLAs and pTLAs:
- IPv6-site: site description
- Inet6num: prefix delegation (one record MUST exist for each
delegation)
- Mntner: contact info for site maintance/administration staff.
Other object MAY be maintained at the discretion of the sites such as
routing policy descriptors, person, or role objects. The Mntner
object MUST make reference to a role or person object, but those MAY
NOT necessarily reside in the 6Bone registry. They can be stored
within any of the Internet registry databases (ARIN, APNIC, RIPE-NCC,
etc.)
6. Guidelines for new sites joining the 6Bone
New sites joining the 6Bone should seek to connect to a transit pNLA
or a pTLA within their region, and preferably as close as possible to
their existing IPv4 physical and routing path for Internet service.
The 6Bone web site at <http://www.6bone.net> has various information
and tools to help find candidate 6bone networks.
Any site connected to the 6Bone MUST maintain a DNS server for
forward name lookups and reverse address lookups. The joining site
MUST maintain the 6Bone objects relative to its site, as describe in
section 5.
The upstream provider MUST delegate the reverse address translation
zone in DNS to the joining site, or have an agreement in place to
perform primary DNS for that downstream. The provider MUST also
create the 6Bone registry inet6num object reflecting the delegated
address space.
Up to date informatino about how to join the 6Bone is available on
the 6Bone Web site at <http://www.6bone.net>.
7. Guidelines for 6Bone pTLA sites
The following rules apply to qualify for a 6Bone pTLA allocation. It
should be recognized that holders of 6Bone pTLA allocations are
expected to provide production quality backbone network services for
the 6Bone.
1. The pTLA Applicant must have a minimum of three (3) months
qualifying experience as a 6Bone end-site or pNLA transit. During
the entire qualifying period the Applicant must be operationally
providing the following:
a. Fully maintained, up to date, 6Bone Registry entries for their
ipv6-site inet6num, mntner, and person objects, including each
tunnel that the Applicant has.
b. Fully maintained, and reliable, BGP4+ peering and connectivity
between the Applicant's boundary router and the appropriate
connection point into the 6Bone. This router must be IPv6
pingable. This criteria is judged by members of the 6Bone
Operations Group at the time of the Applicant's pTLA request.
c. Fully maintained DNS forward (AAAA) and reverse (ip6.int)
entries for the Applicant's router(s) and at least one host
system.
d. A fully maintained, and reliable, IPv6-accessible system
providing, at a mimimum, one or more web pages, describing the
Applicant's IPv6 services. This server must be IPv6 pingable.
2. The pTLA Applicant MUST have the ability and intent to provide
"production-quality" 6Bone backbone service. Applicants must
provide a statement and information in support of this claim.
This MUST include the following:
a. A support staff of two persons minimum, three preferable, with
person attributes registered for each in the ipv6-site object
for the pTLA applicant.
b. A common mailbox for support contact purposes that all support
staff have acess to, pointed to with a notify attribute in the
ipv6-site object for the pTLA Applicant.
3. The pTLA Applicant MUST have a potential "user community" that
would be served by its becoming a pTLA, e.g., the Applicant is a
major provider of Internet service in a region, country, or focus
of interest. Applicant must provide a statement and information in
support this claim.
4. The pTLA Applicant MUST commit to abide by the current 6Bone
operational rules and policies as they exist at time of its
application, and agree to abide by future 6Bone backbone
operational rules and policies as they evolve by consensus of the
6Bone backbone and user community.
When an Applicant seeks to receive a pTLA allocation, it will apply
to the 6Bone Operations Group (see section 8 below) by providing to
the Group information in support of its claims that it meets the
criteria above.
8. 6Bone Operations Group
The 6Bone Operations Group is the group in charge of monitoring and
policing adherence to the current rules. Membership in the 6Bone
Operations Group is mandatory for, and restricted to, sites connected
to the 6Bone.
The 6Bone Operations Group is currently defined by those members of
the existing 6Bone mailing list who represent sites participating in
the 6Bone. Therefore it is incumbent on relevant site contacts to
join the 6Bone mailing list. Instructions on how to join the list are
maintained on the 6Bone web site at < http://www.6bone.net>.
9. Common rules enforcement for the 6bone
Participation in the 6Bone is a voluntary and benevolent undertaking.
However, participating sites are expected to adhere to the rules and
policies described in this document in order to maintain the 6Bone as
a quality tool for the deployment of, and transition to, IPv6
protocols and the products implementing them.
The following is in support of policing adherence to 6Bone rules and
policies:
1. Each pTLA site has committed to implement the 6Bone's rules and
policies, and SHOULD try to ensure they are adhered to by sites
within their administrative control, i.e. those to who prefixes
under their respective pTLA prefix have been delegated.
2. When a site detects an issue, it SHOULD first use the 6Bone
registry to contact the site maintainer and work the issue.
3. If nothing happens, or there is disagreement on what the right
solution is, the issue SHOULD be brought to the 6Bone Operations
Group.
4. When the problem is related to a product issue, the site(s)
involved SHOULD be responsible for contacting the product vendor
and work toward its resolution.
5. When an issue causes major operational problems, backbone sites
SHOULD decide to temporarily set filters in order to restore
service.
10. Security Considerations
The result of incorrect entries in routing tables is usually
unreachable sites. Having guidelines to aggregate or reject routes
will clean up the routing tables. It is expected that using these
rules and policies, routing on the 6Bone will be less sensitive to
denial of service attacks due to misleading routes.
The 6Bone is an IPv6 testbed to assist in the evolution and
deployment of IPv6. Therefore, denial of service or packet disclosure
are to be expected. However, it is the pTLA from where the attack
originated who has ultimate responsibility for isolating and fixing
problems of this nature. It is also every 6Bone site's responsibility
to safely introduce new test systems into the 6Bone, by placing them
at a strategically safe places which will have minimal impact on
other 6Bone sites, should bugs or misconfigurations occur.
11. References
[RFC2373] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC2373, July 1998.
[RFC2471] Hinden, R., Fink, R. and J. Postel, "IPv6 Testing Address
Allocation", RFC2471, December 1998.
[RFC2546] Durand, A. and B. Buclin, "6Bone Routing Practice", RFC
2546, March 1999
[RFC2080] Malkin, G. and R. Minnear, "RIPng for IPv6", RFC2080,
January 1997.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC2119, March 1997.
[RFC2283] Bates, T., Chandra, R., Katz, D. and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC2283, March
1998.
[RIPE-181] Bates, T., Gerich, E., Joncheray, L., Jouanigot, J.,
Karrenberg, D., Terpstra, M. and J. Yu, Representation
of IP Routing Policies in a Routing Registry. Technical
Report ripe-181, RIPE, RIPE NCC, Amsterdam, Netherlands,
October 1994.
12. Authors' Addresses
Rob Rockell
EMail: rrockell@sprint.net
Bob Fink
EMail: fink@es.net
13. Full Copyright Statement
Copyright (C) The Internet Society (2000). All Rights Reserved.
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