Internet DRAFT - draft-xu-isis-routable-ip-address
draft-xu-isis-routable-ip-address
Network Working Group X. Xu
Internet-Draft Huawei
Intended status: Standards Track U. Chunduri
Expires: March 29, 2015 Ericsson
September 25, 2014
Carrying Routable IP Addresses in IS-IS Router Capability TLV
draft-xu-isis-routable-ip-address-01
Abstract
This document proposes two new sub-TLVs of the IS-IS Router
CAPABILITY TLV, called routable IPv4 address sub-TLV and routable
IPv6 address sub-TLV respectively.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Routable IPv4 Address Sub-TLV . . . . . . . . . . . . . . . . 3
4. Routable IPv6 Address Sub-TLV . . . . . . . . . . . . . . . . 3
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. Security Considerations . . . . . . . . . . . . . . . . . . . 4
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
8.1. Normative References . . . . . . . . . . . . . . . . . . 4
8.2. Informative References . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
There are several situations where it is useful for IS-IS routers
within a given area to identify the routable IP address of IS-IS
routers within the same area. In deployments, multiple IP addresses
can be hosted by an IS-IS router for a particular purpose and all
these addresses cannot be represented through the currently defined
TE Router ID TLVs [RFC5305] [RFC6119]. For example, a private
address range used for PQ nodes, as specified in Section 12 of
[I-D.ietf-rtgwg-remote-lfa], can be easily represented through the
sub-TLVs defined in this document without having to parse through all
TE reachability TLVs [RFC5305] [RFC5120] where a receiving node can
not identify if the prefix is an external prefix, an inter-area
leaked prefix or a locally attached prefix. Similarly, in the case
where a topology database is learned by an orchestrator or controller
[I-D.ietf-i2rs-problem-statement], an application can easily
determine the router reachability from a private address range
(specifically for this purpose), advertised through the sub-TLVs
defined in this document.
Meanwhile, there are also several situations where it is required for
IS-IS routers in one area to find correlations between routable IP
addresses and capabilities of IS-IS routers in another area. One
example is the Entropy Label Capability (ELC) advertisement
[I-D.xu-isis-mpls-elc] across the IS-IS domain. In this example,
assume the ELC TLV originated by a router in one area is propagated
to another area, those routers in the latter area need to find
routable IP addresses of the router originating that ELC TLV before
inserting the Entropy Label (EL) for packets going to the Label
Switch Path (LSP) tunnel towards one of the above routable IP
addresses. Another example is the S-BFD discriminator distribution
[I-D.ginsberg-isis-sbfd-discriminator] across the IS-IS domain. In
this example, assume the S-BFD Discriminator sub-TLV originated by a
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router in one area is propagated to another area, those routers in
the latter area need to find routable IP addresses of the router
originating that S-BFD Discriminator sub-TLV so as to set up S-BDF
sessions with that originating router.
However, in the IS-IS Router CAPABILITY TLV as defined in [RFC4971],
which is applicable for both IPv4 IS-IS [RFC1195] [RFC5305] and IPv6
MT IS-IS [RFC5120], there is no such field for containing the
routable IP address. Although TE Router ID sub-TLVs defined in
[RFC5316] can be used to carry routable IP addresses, TE Router ID
sub-TLVs are specifically designed for TE purpose. Therefore, this
document propose two new sub-TLVs of this CAPABILITY TLV to carry a
routable IPv4 and IPv6 address of the router originating the
CAPABILITY TLV respectively. These two sub-TLVs could be used for
non-TE purpose. A router MUST NOT advertise the sub-TLVs defined in
this document if the same has been advertised through TE Router ID
sub-TLVs.
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. Terminology
This memo makes use of the terms defined in [RFC4971].
3. Routable IPv4 Address Sub-TLV
A new sub-TLV of the IS-IS Router Capability TLV, called Routable
IPv4 Address sub-TLV is defined to carry one or more routable /32
IPv4 address of the router originating the CAPABILITY TLV. The Type
of this sub-TLV is TBD, the Length is variable (multiple of 4), and
the Value field contains one or more routable IPv4 address of the
router originating the CAPABILITY TLV. For every IPv4 address of
this type, a corresponding IP reachability TLV [RFC5305] or MT IP
reachability TLV [RFC5120] MUST be included in its LSP. An
implementation receiving a Routable IPv4 Address sub-TLV defined in
this document MUST NOT consider these /32 reachable prefixes in the
standard SPF calculation because this can lead to forwarding loops
when interacting with systems that do not support this TLV.
4. Routable IPv6 Address Sub-TLV
A new sub-TLV of the IS-IS Router Capability TLV, called Routable
IPv6 Address sub-TLV is defined to carry one or more routable /128
IPv6 global address of the router originating the CAPABILITY TLV.
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The Type of this sub-TLV is TBD, the Length is variable (multiple of
16), and the Value field contains one or more routable IPv6 global
address of the router originating the CAPABILITY TLV. For every IPv6
address of this type,a corresponding IPv6 reachability TLV [RFC5308]
orMT IPv6 reachability TLV [RFC5120] MUST be included in its LSP. An
implementation receiving a Routable IPv6 Address sub-TLV defined in
this document MUST NOT consider these /128 reachable prefixes in the
standard SPF calculation because this can lead to forwarding loops
when interacting with systems that do not support this TLV.
5. Acknowledgements
Thanks Karsten Thomann, Anton Smirnov, Joel Jaeggli, Joel M.
Halpern, Wes George and Acee Lindem for their valuable comments on
the initial idea of this draft.
6. IANA Considerations
This memo includes a request to IANA to allocate two sub-TLV type
codes within the IS-IS Router Capability TLV for the Routable IPv4
Address Sub-TLV and the Routable IPv6 Address Sub-TLV respectively.
7. Security Considerations
This document does not introduce any new security risk.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4971] Vasseur, JP., Shen, N., and R. Aggarwal, "Intermediate
System to Intermediate System (IS-IS) Extensions for
Advertising Router Information", RFC 4971, July 2007.
8.2. Informative References
[I-D.ginsberg-isis-sbfd-discriminator]
Ginsberg, L., Akiya, N., and M. Chen, "Advertising S-BFD
Discriminators in IS-IS", draft-ginsberg-isis-sbfd-
discriminator-00 (work in progress), May 2014.
[I-D.ietf-i2rs-problem-statement]
Atlas, A., Nadeau, T., and D. Ward, "Interface to the
Routing System Problem Statement", draft-ietf-i2rs-
problem-statement-04 (work in progress), June 2014.
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[I-D.ietf-rtgwg-remote-lfa]
Bryant, S., Filsfils, C., Previdi, S., Shand, M., and S.
Ning, "Remote LFA FRR", draft-ietf-rtgwg-remote-lfa-06
(work in progress), May 2014.
[I-D.xu-isis-mpls-elc]
Xu, X., Kini, S., Sivabalan, S., and C. Filsfils,
"Signaling Entropy Label Capability Using IS-IS", draft-
xu-isis-mpls-elc-00 (work in progress), December 2013.
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, December 1990.
[RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
Topology (MT) Routing in Intermediate System to
Intermediate Systems (IS-ISs)", RFC 5120, February 2008.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, October 2008.
[RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308, October
2008.
[RFC5316] Chen, M., Zhang, R., and X. Duan, "ISIS Extensions in
Support of Inter-Autonomous System (AS) MPLS and GMPLS
Traffic Engineering", RFC 5316, December 2008.
[RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic
Engineering in IS-IS", RFC 6119, February 2011.
Authors' Addresses
Xiaohu Xu
Huawei
Email: xuxiaohu@huawei.com
Uma Chunduri
Ericsson
Email: uma.chunduri@ericsson.com
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