Origin Validation Community: BGP Prefix Origin Validation State Extended Community
A BGP tag that passes a route's origin validation result between routers inside one network.
Mohapatra, P., Patel, K., Scudder, J., Ward, D., and R. Bush, "BGP Prefix Origin Validation State Extended Community", RFC 8097, DOI 10.17487/RFC8097, March 2017, <https://www.rfc-editor.org/info/rfc8097>.
@misc{rfc8097,
series = {Request for Comments},
number = 8097,
howpublished = {RFC 8097},
publisher = {RFC Editor},
doi = {10.17487/RFC8097},
url = {https://www.rfc-editor.org/info/rfc8097},
author = {P. Mohapatra and K. Patel and J. Scudder and D. Ward and R. Bush},
title = {{BGP Prefix Origin Validation State Extended Community}},
pagetotal = 6,
year = 2017,
month = mar,
} RFC text
Contents
Internet Engineering Task Force (IETF) P. Mohapatra
Request for Comments: 8097 Sproute Networks
Category: Standards Track K. Patel
ISSN: 2070-1721 Arrcus, Inc.
J. Scudder
Juniper Networks
D. Ward
Cisco
R. Bush
Internet Initiative Japan, Inc.
March 2017
BGP Prefix Origin Validation State Extended Community
Abstract
This document defines a new BGP opaque extended community to carry
the origination Autonomous System (AS) validation state inside an
autonomous system. Internal BGP (IBGP) speakers that receive this
validation state can configure local policies that allow it to
influence their decision process.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc8097.
Copyright Notice
Copyright (c) 2017 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
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
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Origin Validation State Extended Community . . . . . . . . . 3
3. Deployment Considerations . . . . . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . 5
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
This document defines a new BGP opaque extended community to carry
the origination AS validation state inside an autonomous system.
IBGP speakers that receive this validation state can configure local
policies that allow it to influence their decision process.
1.1. 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 RFC 2119 [RFC2119].
2. Origin 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 | 0x00 | 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 0x00. 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 route's validation state [RFC6811]. It can
assume the following values:
+-------+-----------------------------+
| Value | Meaning |
+-------+-----------------------------+
| 0 | Lookup result = "valid" |
| 1 | Lookup result = "not found" |
| 2 | Lookup result = "invalid" |
+-------+-----------------------------+
If the router is configured to support the extensions defined in this
document, it SHOULD attach the origin validation state extended
community to BGP UPDATE messages sent to IBGP peers by mapping the
computed validation state in the last octet of the extended
community. Similarly, a receiving BGP speaker, in the absence of
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
origin 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 origin 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].
3. Deployment Considerations
In deployment scenarios in which not all the speakers in an
autonomous system are upgraded to support the extensions defined in
this document, it is necessary to define policies that match on the
origin validation extended community and set another BGP attribute
[RFC6811] that influences selection of the best path in the same way
that an implementation of this extension would.
4. IANA Considerations
IANA has registered the value 0x00, with the name "BGP Origin
Validation State Extended Community", in the "Non-Transitive Opaque
Extended Community Sub-Types" registry.
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 origin validation extended
community.
The security considerations provided in [RFC6811] apply equally to
this application of origin 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. References
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
February 2006, <http://www.rfc-editor.org/info/rfc4360>.
[RFC6811] Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R.
Austein, "BGP Prefix Origin Validation", RFC 6811,
DOI 10.17487/RFC6811, January 2013,
<http://www.rfc-editor.org/info/rfc6811>.
6.2. Informative References
[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, DOI 10.17487/RFC4272, January 2006,
<http://www.rfc-editor.org/info/rfc4272>.
[RFC4593] Barbir, A., Murphy, S., and Y. Yang, "Generic Threats to
Routing Protocols", RFC 4593, DOI 10.17487/RFC4593,
October 2006, <http://www.rfc-editor.org/info/rfc4593>.
[RFC7454] Durand, J., Pepelnjak, I., and G. Doering, "BGP
Operations and Security", BCP 194, RFC 7454,
DOI 10.17487/RFC7454, February 2015,
<http://www.rfc-editor.org/info/rfc7454>.
[RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K.
Patel, "Revised Error Handling for BGP UPDATE Messages",
RFC 7606, DOI 10.17487/RFC7606, August 2015,
<http://www.rfc-editor.org/info/rfc7606>.
[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 Wesley George, Roque Gagliano, and Bruno Decraene on
this document.
Authors' Addresses
Pradosh Mohapatra
Sproute Networks
Email: mpradosh@yahoo.com
Keyur Patel
Arrcus, Inc.
Email: keyur@arrcus.com
John Scudder
Juniper Networks
1194 N. Mathilda Ave
Sunnyvale, CA 94089
United States of America
Email: jgs@juniper.net
Dave Ward
Cisco
170 W. Tasman Drive
San Jose, CA 95124
United States of America
Email: dward@cisco.com
Randy Bush
Internet Initiative Japan, Inc.
5147 Crystal Springs
Bainbridge Island, WA 98110
United States of America
Email: randy@psg.com
AI ELI5
On this page
§1Why Carry Validation State
RFC 8097 defines a new BGP opaque extended community that carries the origination AS validation state inside an autonomous system. Internal BGP (IBGP) speakers that receive this state can configure local policies that let it influence their decision process.
The validation state itself is the one computed by origin validation as described in RFC 6811. This document only adds a way to hand that result from one router to another.
One router does the checking and writes the result on a tag. The other routers in the same network can read the tag and act on it.
§2The Community Encoding
The community is an opaque extended community as defined in RFC 4360. It is eight octets long. The high-order octet of the extended Type field is 0x43, which indicates it is non-transitive. The low-order octet of the Type field, as assigned by IANA, is 0x00.
The Reserved fields MUST be set to 0 and are ignored on receipt. The last octet is an unsigned integer that gives the route's validation state. Three values are defined: 0 means the lookup result is valid, 1 means not found, and 2 means invalid.
The tag is a small fixed-size label. Most of it is empty space, and the last piece holds a number: 0, 1 or 2, meaning good, unknown or bad.
| Field | Name | Size | Value | Description |
|---|---|---|---|---|
TYPE-HIGH | Type (high) | 1 byte | 0x43 | High-order type octet; indicates non-transitive. |
TYPE-LOW | Type (low) | 1 byte | 0x00 | Sub-type assigned by IANA. |
RESERVED-1 | Reserved | 2 bytes | Set to 0 and ignored on receipt. | |
RESERVED-2 | Reserved | 3 bytes | Set to 0 and ignored on receipt. | |
STATE | Validation state | 1 byte | The route's validation state. |
- 0valid — Lookup result is valid.
- 1not found — Lookup result is not found.
- 2invalid — Lookup result is invalid.
§3Sending and Receiving Rules
A router configured to support this extension SHOULD attach the community to BGP UPDATE messages it sends to IBGP peers, mapping its computed validation state into the last octet. A receiving BGP speaker that has no validation state set from local data SHOULD derive one from the last octet of the community, if present.
An implementation SHOULD NOT send more than one instance. If several arrive, it MUST disregard all but the one with the numerically greatest validation state value. If the value is greater than the largest specified value (2), the implementation MUST apply a strategy similar to attribute discard from RFC 7606: discard the erroneous community and log the error for further analysis.
Across AS borders the rules differ. By default, implementations MUST drop the community when it is received from an External BGP (EBGP) peer, without processing it, and SHOULD NOT send it to EBGP peers. It SHOULD be possible to configure an implementation to send or accept it when warranted, for example when two adjacent ASes are under the same administration.
A router puts the tag on routes it passes to friends inside its own network. If it gets several tags, it believes the worst one. Tags from outside networks are thrown away unless the owner says otherwise.
§4Deployment Considerations
Not every speaker in an autonomous system may be upgraded to support the extension. In that case it is necessary to define policies that match on the origin validation extended community and set another BGP attribute that influences best-path selection, in the same way an implementation of this extension would. The text refers to RFC 6811 for that attribute-setting approach.
If some routers in the network do not understand the tag yet, you give them a rule that turns the tag into something they do understand.
§5IANA Registration
IANA registered the value 0x00, with the name "BGP Origin Validation State Extended Community", in the "Non-Transitive Opaque Extended Community Sub-Types" registry.
The official list of tag types got a new entry so nobody else uses the same number for something different.
§6Security Considerations
The considerations in RFC 4272 continue to apply. Because the community will generally be used to affect route selection, the analysis of falsification in Section 4.5 of RFC 4593 is relevant. The text says these issues are neither new nor unique to this community. The security considerations of RFC 6811 apply equally.
The scheme lets router A outsource validation to router B. The participating routers should therefore have an appropriate trust relationship: B should trust A, for example because they are under the same administrative control. The security of the TCP connection between them should also be considered; see Section 5.1 of RFC 7454.
If you let a friend do the checking for you, you must trust that friend and make sure nobody can whisper false answers to you on the way.