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Network Working Group
Request for Comments: 2772
Obsoletes: 2546
Category: Informational
R. Rockell
Sprint
R. Fink
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 © 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 [RFC 2283], 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 [RFC 2119].

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
  1. site local prefixes
  1. loopback and unspecified prefixes
  1. multicast prefixes
  1. IPv4-compatible prefixes
  1. IPv4-mapped prefixes
  1. default routes
  1. yet undefined unicast prefixes (from a different /3 prefix)
  1. inter-site links issues
  1. 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, RFC 2471 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.
  1. 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.

  1. 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.
  1. 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.
  1. When a site detects an issue, it SHOULD first use the 6Bone registry to contact the site maintainer and work the issue.
  1. If nothing happens, or there is disagreement on what the right solution is, the issue SHOULD be brought to the 6Bone Operations Group.
  1. 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.
  1. 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

   [RFC 2373] Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 2373, July 1998.
   
   [RFC 2471] Hinden, R., Fink, R. and J. Postel, "IPv6 Testing Address
              Allocation", RFC 2471, December 1998.
   
   [RFC 2546] Durand, A. and B. Buclin, "6Bone Routing Practice", RFC
              2546, March 1999
   
   [RFC 2080] Malkin, G. and R. Minnear, "RIPng for IPv6", RFC 2080,
              January 1997.
   
   [RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate
              Requirement  Levels", BCP 14, RFC 2119, March 1997.
   
   [RFC 2283] Bates, T., Chandra, R., Katz, D. and Y. Rekhter,
              "Multiprotocol Extensions for BGP-4", RFC 2283, 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 © The Internet Society (2000). All Rights Reserved.

This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English.

The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns.

This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

Funding for the RFC Editor function is currently provided by the Internet Society.