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16 RFC 8207
Network Working Group R. Bush
Internet-Draft Internet Initiative Japan
Intended status: BCP March 10, 2012
Expires: September 11, 2012
BGPsec Operational Considerations
draft-ietf-sidr-bgpsec-ops-03
Abstract
Deployment of the BGPsec architecture and protocols has many
operational considerations. This document attempts to collect and
present them. It is expected to evolve as BGPsec is formalized and
initially deployed.
Requirements Language
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].
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
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."
This Internet-Draft will expire on September 11, 2012.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . 3
3. RPKI Distribution and Maintenance . . . . . . . . . . . . . . . 3
4. AS/Router Certificates . . . . . . . . . . . . . . . . . . . . 3
5. Within a Network . . . . . . . . . . . . . . . . . . . . . . . 4
6. Considerations for Edge Sites . . . . . . . . . . . . . . . . . 4
7. Routing Policy . . . . . . . . . . . . . . . . . . . . . . . . 5
8. Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
9. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
11.1. Normative References . . . . . . . . . . . . . . . . . . . 7
11.2. Informative References . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
BGPsec is a new protocol with many operational considerations. It is
expected to be deployed incrementally over a number of years. As
core BGPsec-capable routers may require large memory and/or modern
CPUs, it is thought that origin validation based on the RPKI will
occur over the next one to three years and that BGPsec will start to
deploy late in that window.
BGPsec relies on widespread propagation of the Resource Public Key
Infrastructure (RPKI) [RFC6480]. How the RPKI is distributed and
maintained globally and within an operator's infrastructure may be
different for BGPsec than for origin validation.
BGPsec need be spoken only by an AS's eBGP speaking, AKA border,
routers, and is designed so that it can be used to protect
announcements which are originated by small edge routers. This has
special operational considerations.
Different prefixes have different timing and replay protection
considerations.
2. Suggested Reading
It is assumed that the reader understands BGP, [RFC4271], BGPsec,
[I-D.lepinski-bgpsec-overview], the RPKI, see [RFC6480], the RPKI
Repository Structure, see [RFC6481], and ROAs, see [RFC6482].
3. RPKI Distribution and Maintenance
All non-ROA considerations in the section on RPKI Distribution and
Maintenance of [I-D.ietf-sidr-origin-ops] apply.
4. AS/Router Certificates
As described in [I-D.ymbk-bgpsec-rtr-rekeying] routers MAY be capable
of generating their own public/private key-pairs and having their
certificates signed and published in the RPKI by the RPKI CA system,
and/or MAY be given public/private key-pairs by the operator.
A site/operator MAY use a single certificate/key in all their
routers, one certificate/key per router, or any granularity in
between.
A large operator, concerned that a compromise of one router's key
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would make other routers vulnerable, MAY accept a more complex
certificate/key distribution burden to reduce this exposure.
On the other extreme, an edge site with one or two routers MAY use a
single certificate/key.
5. Within a Network
BGPsec is spoken by edge routers in a network, those which border
other networks/ASs.
In a fully BGPsec enabled AS, Route Reflectors MUST have BGPsec
enabled if and only if there are eBGP speakers in their client cone,
i.e. an RR client or the transitive closure of their customers'
customers' customers' ....
A BGPsec capable router MAY use the data it receives to influence
local policy within its network, see Section 7. In deployment this
policy should fit into the AS's existing policy, preferences, etc.
This allows a network to incrementally deploy BGPsec capable border
routers.
eBGP speakers which face more critical peers or up/downstreams would
be candidates for the earliest deployment. Both securing one's own
announcements and validating received announcements should be
considered in partial deployment.
As they are not signed, an eBGP listener SHOULD NOT strongly trust
unsigned markings such as communities received across a trust
boundary.
6. Considerations for Edge Sites
An edge site which does not provide transit and trusts its
upstream(s) SHOULD only originate a signed prefix announcement and
need not validate received announcements.
BGPsec protocol capability negotiation provides for a speaker signing
the data it sends but being unable to accept signed data. Thus a
smallish edge router may hold only its own signing key(s) and sign
it's announcement but not receive signed announcements and therefore
not need to deal with the majority of the RPKI. Thus such routers
CPU, RAM, and crypto needs are trivial and additional hardware should
not be needed.
As the vast majority (84%) of ASs are stubs, and they announce the
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majority of prefixes, this allows for simpler and cheaper early
incremental deployment. It may also mean that edge sites concerned
with routing security will be attracted to upstreams which support
BGPsec.
7. Routing Policy
Unlike origin validation based on the RPKI, BGPsec marks a received
announcement as Valid or Invalid, there is no NotFound state. How
this is used in routing is up to the operator's local policy. See
[I-D.ietf-sidr-pfx-validate].
As BGPsec will be rolled out over years and does not allow for
intermediate non-signing edge routers, coverage will be spotty for a
long time. Hence a normal operator's policy SHOULD NOT be overly
strict, perhaps preferring valid announcements and giving very low
preference, but still using, invalid announcements.
A BGPsec speaker validates signed paths at the eBGP edge.
Local policy on the eBGP edge MAY convey the validation state of a
BGP signed path through normal local policy mechanisms, e.g. setting
a BGP community, or modifying a metric value such as local-preference
or MED. Some MAY choose to use the large Local-Pref hammer. Others
MAY choose to let AS-Path rule and set their internal metric, which
comes after AS-Path in the BGP decision process.
Because of possible RPKI version skew, an AS Path which does not
validate at router R0 might validate at R1. Therefore, signed paths
that are invalid and yet propagated (because they are chosen as best
path) SHOULD have their signatures kept intact and MUST be signed if
sent to external BGPsec speakers.
This implies that updates which a speaker judges to be invalid MAY be
propagated to iBGP peers. Therefore, unless local policy ensures
otherwise, a signed path learned via iBGP MAY be invalid. If needed,
the validation state SHOULD be signaled by normal local policy
mechanisms such as communities or metrics.
On the other hand, local policy on the eBGP edge might preclude iBGP
or eBGP announcement of signed AS Paths which are invalid.
A BGPsec speaker receiving a path SHOULD perform origin validation
per [I-D.ietf-sidr-pfx-validate].
If it is known that a BGPsec neighbor is not a transparent route
server, and the router provides a knob to disallow a received pCount
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(prepend count, zero for transparent route servers) of zero, that
knob SHOULD be applied. Routers should default to this knob
disallowing pCount 0.
To prevent exposure of the internals of BGP Confederations [RFC5065],
a BGPsec speaker which is a Member-AS of a Confederation MUST NOT
sign updates sent to another Member-AS of the same Confederation.
8. Notes
For protection from attacks replaying BGP data on the order of a day
or longer old, re-keying routers with new keys (previously)
provisioned in the RPKI is sufficient. For one procedure, see
[I-D.rogaglia-sidr-bgpsec-rollover]
Like the DNS, the global RPKI presents only a loosely consistent
view, depending on timing, updating, fetching, etc. Thus, one cache
or router may have different data about a particular prefix than
another cache or router. There is no 'fix' for this, it is the
nature of distributed data with distributed caches.
Operators who manage certificates SHOULD have RPKI Ghostbuster
Records (see [I-D.ietf-sidr-ghostbusters]), signed indirectly by End
Entity certificates, for those certificates on which others' routing
depends for certificate and/or ROA validation.
Operators should be aware of impending algorithm transitions, which
will be rare and slow-paced, see see
[I-D.ietf-sidr-algorithm-agility]. They should work with their
vendors to ensure support for new algorithms.
As a router must evaluate certificates and ROAs which are time
dependent, routers' clocks MUST be correct to a tolerance of
approximately an hour.
If a router has reason to believe its clock is seriously incorrect,
e.g. it has a time earlier than 2011, it SHOULD NOT attempt to
validate incoming updates. It SHOULD defer validation until it
believes it is within reasonable time tolerance.
Servers should provide time service, such as [RFC5905], to client
routers.
9. Security Considerations
The major security considerations for the BGPsec protocol are
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described in [I-D.ietf-sidr-bgpsec-protocol].
10. IANA Considerations
This document has no IANA Considerations.
11. References
11.1. Normative References
[I-D.ietf-sidr-bgpsec-protocol]
Lepinski, M., "BGPSEC Protocol Specification",
draft-ietf-sidr-bgpsec-protocol-01 (work in progress),
October 2011.
[I-D.ietf-sidr-ghostbusters]
Bush, R., "The RPKI Ghostbusters Record",
draft-ietf-sidr-ghostbusters-16 (work in progress),
December 2011.
[I-D.ietf-sidr-origin-ops]
Bush, R., "RPKI-Based Origin Validation Operation",
draft-ietf-sidr-origin-ops-13 (work in progress),
November 2011.
[I-D.lepinski-bgpsec-overview]
Lepinski, M. and S. Turner, "An Overview of BGPSEC",
draft-lepinski-bgpsec-overview-00 (work in progress),
March 2011.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support
Secure Internet Routing", RFC 6480, February 2012.
[RFC6481] Huston, G., Loomans, R., and G. Michaelson, "A Profile for
Resource Certificate Repository Structure", RFC 6481,
February 2012.
[RFC6482] Lepinski, M., Kent, S., and D. Kong, "A Profile for Route
Origin Authorizations (ROAs)", RFC 6482, February 2012.
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11.2. Informative References
[I-D.ietf-sidr-algorithm-agility]
Gagliano, R., Kent, S., and S. Turner, "Algorithm Agility
Procedure for RPKI.", draft-ietf-sidr-algorithm-agility-05
(work in progress), January 2012.
[I-D.ietf-sidr-pfx-validate]
Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R.
Austein, "BGP Prefix Origin Validation",
draft-ietf-sidr-pfx-validate-03 (work in progress),
October 2011.
[I-D.rogaglia-sidr-bgpsec-rollover]
Gagliano, R., Patel, K., and B. Weis, "BGPSEC router key
roll-over as an alternative to beaconing",
draft-rogaglia-sidr-bgpsec-rollover-00 (work in progress),
March 2012.
[I-D.ymbk-bgpsec-rtr-rekeying]
Turner, S., Patel, K., and R. Bush, "Router Keying for
BGPsec", draft-ymbk-bgpsec-rtr-rekeying-00 (work in
progress), March 2012.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous
System Confederations for BGP", RFC 5065, August 2007.
[RFC5905] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network
Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, June 2010.
Author's Address
Randy Bush
Internet Initiative Japan
5147 Crystal Springs
Bainbridge Island, Washington 98110
US
Phone: +1 206 780 0431 x1
Email: randy@psg.com
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