Internet Engineering Task Force (IETF) O. Borchert
Internet-Draft D. Montgomery
Intended status: Standards Track USA NIST
Expires: September 27, 2019 March 26, 2019
BGPsec Validation State Signaling
draft-borchert-sidrops-bgpsec-validation-signaling-00
Abstract
This document defines a new BGP opaque extended community to carry
the BGPsec path validation state inside an autonomous system.
Internal BGP (IBGP) speakers that receive this community string can
use the embedded BGPsec validation state and configure local policies
that allow it being used to influence their decision process. This
is specially helpful because (Section 5) of [RFC8205] specifically
allows putting BGPsewc path validation temporarily on hold. This
would allow to reduce the load of validation especially from IBGP
learned routes.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Suggested Reading . . . . . . . . . . . . . . . . . . . . . . 3
3. BGPsec Validation State Extended Community . . . . . . . . . . 3
4. Deployment Considerations . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6.1. Normative References . . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . . 6
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6
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1. Introduction
This document defines a new BGP opaque extended community to carry
the BGPsec path validation state inside an autonomous system.
Internal BGP (IBGP) speakers that receive this community string can
use the embedded BGPsec validation state and configure local policies
that allow it being used to influence their decision process. This
is specially helpful because (Section 5) of [RFC8205] specifically
allows putting BGPsewc path validation temporarily on hold. This
would allow to reduce the load of validation especially from IBGP
learned routes.
1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Suggested Reading
It is assumed that the reader understands BGPsec [RFC8205].
3. BGPsec Validation State Extended Community
The origin validation state extended community is an opaque extended
community [RFC4360] with the following encoding:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x43 | TBD | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |validationstate|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The value of the high-order octet of the extended Type field is 0x43,
which indicates it is non-transitive. The value of the low-order
octet of the extended Type field as assigned by IANA is TBD. The
Reserved field MUST be set to 0 and ignored upon the receipt of this
community. The last octet of the extended community is an unsigned
integer that gives the BGPsec route's validation state [RFC8205] and
[BORCHERT]. It can assume the following values:
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+-------+------------------------------+
| Value | Meaning |
+-------+------------------------------+
| 0 | Lookup result = "unverified" |
| 1 | Lookup result = "valid" |
| 2 | Lookup result = "invalid" |
+-------+------------------------------+
If the router is configured to support the extensions defined in this
document, it SHOULD attach the BGPsec path validation state extended
community to BGP UPDATE messages sent to IBGP peers by mapping the
validation state in the last octet of the extended community.
Similarly, a receiving BGP speaker, in the absence of a validation
state set based on local data, SHOULD derive a validation state from
the last octet of the extended community, if present.
An implementation SHOULD NOT send more than one instance of the
BGPsec path validation state extended community. However, if more
than one instance is received, an implementation MUST disregard all
instances other than the one with the numerically greatest validation
state value. If the value received is greater than the largest
specified value (2), the implementation MUST apply a strategy similar
to attribute discard [RFC7606] by discarding the erroneous community
and logging the error for further analysis.
By default, implementations MUST drop the BGPsec validation state
extended community if received from an External BGP (EBGP) peer,
without processing it further. Similarly, by default, an
implementation SHOULD NOT send the community to EBGP peers. However,
it SHOULD be possible to configure an implementation to send or
accept the community when warranted. An example of a case where the
community would reasonably be received from, or sent to, an EBGP peer
is when two adjacent ASes are under control of the same
administration. A second example is documented in [SIDR-RPKI].
4. Deployment Considerations
As specified in (Section 5) of [RFC8205] "a BGPsec speaker MAY
temporarily defer validation of incoming BGPsec UPDATE messages. The
treatment of such BGPsec UPDATE messages, whose validation has been
deferred, is a matter of local policy". Furthermore one can envision
that the operator of a BGPsec router decides to defer BGPsec
validation learned via IBGP (including a trusted EBGP peer for
instance controlled by the same operator as lined out in Section 3)
when already validated by the peer. The router then will use the
validation result learned via the community string and apply it the
the route. In case the peer did send the validation state
unverified, the receiving router SHOULD apply the validation state
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"unverified" and perform BGPsec path validation as described in
(section 5.2) of [RFC8205].
5. Security Considerations
Security considerations such as those described in [RFC4272] continue
to apply. Because this document introduces an extended community
that will generally be used to affect route selection, the analysis
in Section 4.5 ("Falsification") of [RFC4593] is relevant. These
issues are neither new nor unique to the validation extended
community.
The security considerations provided in [RFC8205] apply equally to
this application of BGPsec path validation. In addition, this
document describes a scheme where router A outsources validation to
some router B. If this scheme is used, the participating routers
should have the appropriate trust relationship -- B should trust A
either because they are under the same administrative control or for
some other reason (for example, consider [SIDR-RPKI]). The security
properties of the TCP connection between the two routers should also
be considered. See Section 5.1 of [RFC7454] for advice regarding
protection of the TCP connection.
6. IANA Considerations
IANA shall assign a new value from the "BGP Opaque Extended
Community" type registry from the non-transitive range, to be called
"BGPsec Validation State Extended Community".
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6. References
6.1. Normative References
[BORCHERT] Borchert, O., Montgomery, D., "BGPsec Validation State
Unverified", draft-borchert-sidr-bgpsec-validation-state-
unverified, <httpd://https://tools.ietf.org/html/draft-
borchert-sidrops-bgpsec-state-unverified-00>
8.2. Informative References
[SIDR-RPKI] King, T., Kopp, D., Lambrianidis, A., and A. Fenioux,
"Signaling Prefix Origin Validation Results from a Route-
Server to Peers", Work in Progress,
draft-ietf-sidrops-route-server-rpki-light-01, January
2017.
Acknowledgements
The authors would like to acknowledge the valuable review and
suggestions from K. Sriram on this document.
Authors' Addresses
Oliver Borchert
National Institute of Standards and Technology (NIST)
100 Bureau Drive
Gaithersburg, MD 20899
United States of America
Email: oliver.borchert@nist.gov
Doug Montgomery
National Institute of Standards and Technology (NIST)
100 Bureau Drive
Gaithersburg, MD 20899
United States of America
Email: dougm@nist.gov
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