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Versions: 00 01 02 03 04 RFC 2772

INTERNET-DRAFT                                       R. Rockell (Sprint)
Obsoletes: 2546                                          R. Fink (ESnet)
Category: Informational                                21 December 1999


                   6Bone Backbone Routing Guidelines
                   <draft-ietf-ngtrans-harden-04.txt>

Status of this Memo

This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.

Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups.  Note that
other groups may also distribute working documents as Internet-
Drafts.

Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time.  It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."

The list of current Internet-Drafts can be accessed at
    <http://www.ietf.org/ietf/1id-abstracts.txt>

The list of Internet-Draft Shadow Directories can be accessed at
   <http://www.ietf.org/shadow.html>

This draft expires on 21 June 2000.

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 guildelines by which to deploy IPv6 routing equipment.

This document provides a set of guildelines 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. Scope of this document.............................................
3. Common Rules for the 6bone.........................................
    3.1 Link-local prefixes
    3.2 Site-local prefixes
    3.3 Loopback and unspecified prefixes
    3.4 Multicast prefixes
    3.5 IPv4 compatible prefixes
    3.6 IPv4-mapped prefixes
    3.7 Default routes
    3.8 Yet undefined unicast prefixes
    3.9 Inter-site links
    3.10 6to4 Prefixes
    3.11 Aggregation & advertisement issues
4. Routing Policies for the 6bone.....................................
5. The 6Bone Registry.................................................
6. Guidelines for new sites joining the 6Bone.........................
7. Guidelines for 6Bone pTLA sites....................................
8. 6Bone Operations group.............................................
9. Common rules enforcement for the 6bone.............................
10. Security Considerations...........................................
11. References........................................................
12. Authors' Addresses................................................

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

   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 draft.

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 draft, 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

[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 (deceased), "IPv6
            Testing Address Allocation", RFC 2471, December 1998.

[RFC 2546] Durand, A., Buclin, B, "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
rrockell@sprint.net

Bob Fink
fink@es.net


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