Internet DRAFT - draft-dong-idr-node-target-ext-comm
draft-dong-idr-node-target-ext-comm
Network Working Group J. Dong
Internet-Draft S. Zhuang
Intended status: Standards Track Huawei Technologies
Expires: 12 January 2023 G. Van de Velde
Nokia
11 July 2022
BGP Extended Community for Identifying the Target Nodes
draft-dong-idr-node-target-ext-comm-05
Abstract
BGP has been used to distribute different types of routing and policy
information. In some cases, the information distributed may be only
intended for one or a particular group of BGP nodes in the network.
Currently BGP does not have a generic mechanism of designating the
target nodes of the routing information. This document defines a new
type of BGP Extended Community called "Node Target". The mechanism
of using the Node Target Extended Community to steer BGP route
distribution to particular BGP nodes is specified.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 12 January 2023.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
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Provisions Relating to IETF Documents (https://trustee.ietf.org/
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Please review these documents carefully, as they describe your rights
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and restrictions with respect to this document. Code Components
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Node Target Extended Communities . . . . . . . . . . . . . . 3
3. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Compatibility Considerations . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
BGP [RFC4271] has been used to distribute different types of routing
and policy information. In some cases, the information distributed
may be only intended for one or a group of receiving BGP nodes in the
network. One typical use case is the distribution of BGP Flow Spec
[RFC8955] [RFC8956] rules only to a particular group of BGP nodes.
Such a targeted distribution mechanism is considered useful as it can
save the resources on nodes which do not need that information.
Currently BGP does not have a generic mechanism of designating the
set of nodes to which the information is to be distributed. Route
Target (RT) as defined in [RFC4364] was designed for the matching of
VPN routes into the target VPN Routing and Forwarding tables (VRFs)
on the PE nodes. [I-D.ietf-idr-segment-routing-te-policy] introduces
the mechanism of steering the SR Policy information to the target
head end node based on RT, it is only applicable to the SR Policy
Address Family. Although it is possible to reuse RT to control the
distribution of non-VPN information to one or a group of receiving
nodes, such mechanism is not applicable when the information to be
distributed is VPN-specific and is advertised with another set of RTs
for the VRF matching, as the matching or any of the VPN RT in the BGP
route would result in that route being imported to a local VRF,
regardless of whether the receiving node is the target node or not.
Thus a general mechanism which is independent from the control of VPN
route to VRF import is needed.
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Another possible approach is to configure, on each router, a
community and the corresponding policies to match the community to
determine whether to accept the received routes or not. Such
mechanism relies on manual configuration thus is considered error-
prone. It is preferable by some operators that an automatic approach
can be provided, which would make the operation much easier.
This document defines a new type of BGP Extended Community called
"Node Target". The mechanism of using the Node Target extended
community to control the BGP route distribution only to particular
BGP nodes is also specified.
1.1. Requirements Language
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. Node Target Extended Communities
This section defines a new BGP Extended Community [RFC4360] called
"Node Target Extended Community". It can be a transitive extended
community with the high-order octet of the type set to 0x01, or a
non-transitive extended community with the high-order octet type set
to 0x41. The sub-type of the Node Target Extended Community is TBA.
The format of Node Target Extended Community is shown in Figure 1.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x01 or 0x41 | Sub-Type(TBA) | Target BGP Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Target BGP Identifier (cont.) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1. Node Target extended community
Where:
Target BGP Identifier (4 octets): The BGP Identifier of a target
node. It is a 4-octet, unsigned, non-zero integer as defined in
[RFC6286].
Reserved field (2 octets): Reserved for future use, MUST be set to
zero on transmission and ignored on receipt.
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One or more Node Target extended communities MAY be carried in an
Update message to designate a group of target BGP nodes.
3. Procedures
In this section, the mechanism for intra-domain scenario is
described, the mechanism for inter-domain scenario is for further
study. The domain here refers to an administrative domain, which may
consists of one or multiple ASes managed by a single operator.
When a network controller or BGP speaker plans to advertise some BGP
routing or policy information only to one or a group of BGP nodes in
the network, it MUST put the BGP Identifier of each target node into
the Node Target extended communities, and attach the Node Target
extended communities to the routes or policies to be advertised.
When a BGP speaker receives a BGP Update which contains one or more
Node Target extended communities, it MUST check the target BGP
Identifiers carried in the Node Target extended communities of the
Update.
* If the target BGP Identifier in any of the Node Target extended
community matches with the local BGP Identifier, this node is one
of the target nodes of the Update, the information in the Update
is eligible to be kept and installed on this node.
- If this node is a Route Reflector, and in the Update there is
one or more Node Target extended communities which contains
non-local BGP Identifiers, information in the Update are
eligible be reflected to its peers according to the rules
defined in [RFC4456]. The default behavior for the RR in this
case is to reflect the Update to all its peers without checking
their BGP Identifiers. Depends on a configurable policy, the
RR MAY further check the BGP Identifiers of its peers to
determine the set of peers which are the target nodes of the
Update, and only reflect the information in the Update to the
matched BGP peers.
- If this node is an Autonomous System Border Router (ASBR), and
the BGP Identifiers of one or more of its EBGP peers match with
the Node Target extended communities in the Update, information
in the Update is eligible to be advertised to the matched EBGP
peers.
* If the target BGP Identifier in any of the Node target extended
community does not match with the local BGP Identifier, this node
is not the target node of Update, the information in the Update is
not eligible to be installed on this node.
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- If this node is a Route Reflector, information in the Update is
eligible to be reflected to its peers according to the rules
defined in [RFC4456]. The default behavior for the RR in this
case is to reflect the Update to all its peers without checking
their BGP Identifiers. Depends on a configurable policy, the
RR MAY check the BGP Identifiers of its peers to determine the
set of peers which are the target nodes of the Update, and only
reflect the information in the Update to the matched BGP peers.
4. Compatibility Considerations
The Node Target extended community introduced in this document can be
deployed incrementally in the network. For BGP speakers which
understand the Node Target extended community, it is used to
determine whether the nodes are the target nodes of the Update. For
BGP speakers which do not understand the Node Target extended
community, it will be ignored and the information in the Update will
be processed and advertised based on normal BGP procedure. Although
this could ensure that the target nodes can always obtain the
information needed, this may result in unnecessary state maintained
on the legacy BGP nodes. If the information advertised is the Flow
Spec rules, the legacy BGP speakers may install unnecessary Flowspec
rules, this may have impact on traffic which matches such rules, thus
may result in unexpected traffic steering or filtering behaviors on
such nodes. This may be mitigated by setting appropriate routing
policies on the legacy BGP nodes.
5. IANA Considerations
This document requests that IANA assigns one new sub-type for "Node
Target Extended Community" from the "Transitive IPv4-Address-Specific
Extended Community" registry of the "BGP Extended Communities"
registry.
This document requests that IANA assigns the same sub-type for "Node
Target Extended Community" from the "Non-Transitive IPv4-Address-
Specific Extended Community" registry of the "BGP Extended
Communities" registry.
6. Security Considerations
The mechanism defined in this document can limit the scope of the
receiving nodes of BGP Updates, which make it possible for an
attacker to do fine-grained targeting of malicious BGP Updates only
to a restricted set of routers. This would potentially make it more
difficult for a network administrator to discover an attack. This
may be mitigated by filtering the Node Target Extended Communities at
the administrative network boundaries.
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7. Contributors
Haibo Wang
Email: rainsword.wang@huawei.com
8. Acknowledgements
The authors would like to thank Zhenbin Li, Ercin Torun, Jeff Haas,
Robert Raszuk and John Scudder for the review and discussion of this
document.
9. References
9.1. 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,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
February 2006, <https://www.rfc-editor.org/info/rfc4360>.
[RFC4456] Bates, T., Chen, E., and R. Chandra, "BGP Route
Reflection: An Alternative to Full Mesh Internal BGP
(IBGP)", RFC 4456, DOI 10.17487/RFC4456, April 2006,
<https://www.rfc-editor.org/info/rfc4456>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
9.2. Informative References
[I-D.ietf-idr-segment-routing-te-policy]
Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P.,
Jain, D., and S. Lin, "Advertising Segment Routing
Policies in BGP", Work in Progress, Internet-Draft, draft-
ietf-idr-segment-routing-te-policy-18, 16 June 2022,
<https://www.ietf.org/archive/id/draft-ietf-idr-segment-
routing-te-policy-18.txt>.
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[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
2006, <https://www.rfc-editor.org/info/rfc4364>.
[RFC5575] Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J.,
and D. McPherson, "Dissemination of Flow Specification
Rules", RFC 5575, DOI 10.17487/RFC5575, August 2009,
<https://www.rfc-editor.org/info/rfc5575>.
[RFC6286] Chen, E. and J. Yuan, "Autonomous-System-Wide Unique BGP
Identifier for BGP-4", RFC 6286, DOI 10.17487/RFC6286,
June 2011, <https://www.rfc-editor.org/info/rfc6286>.
[RFC8955] Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
Bacher, "Dissemination of Flow Specification Rules",
RFC 8955, DOI 10.17487/RFC8955, December 2020,
<https://www.rfc-editor.org/info/rfc8955>.
[RFC8956] Loibl, C., Ed., Raszuk, R., Ed., and S. Hares, Ed.,
"Dissemination of Flow Specification Rules for IPv6",
RFC 8956, DOI 10.17487/RFC8956, December 2020,
<https://www.rfc-editor.org/info/rfc8956>.
Authors' Addresses
Jie Dong
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing
100095
China
Email: jie.dong@huawei.com
Shunwan Zhuang
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing
100095
China
Email: zhuangshunwan@huawei.com
Gunter Van de Velde
Nokia
Antwerp
Belgium
Email: gunter.van_de_velde@nokia.com
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