IS-IS for IP Internets P. Sarkar, Ed.
Internet-Draft H. Gredler
Intended status: Standards Track S. Hegde
Expires: January 2, 2015 Juniper Networks, Inc.
S. Litkowski
B. Decraene
Orange
Z. Li
Huawei Technologies
H. Raghuveer
July 1, 2014
Advertising Per-node Admin Tags in IS-IS
draft-psarkar-isis-node-admin-tag-02
Abstract
This document describes an extension to IS-IS protocol [ISO10589],
[RFC1195] to add an optional operational capability, that allows
tagging and grouping ofthe nodes in an IS-IS domain. This allows
simple management and easy control over route and path selection,
based on local configured policies.
This document describes the protocol extensions to disseminate per-
node admin-tags in IS-IS protocols.
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].
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
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Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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This Internet-Draft will expire on January 2, 2015.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Administrative Tag . . . . . . . . . . . . . . . . . . . . . 2
3. TLV format . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Per-node Admin Tag sub-TLV . . . . . . . . . . . . . . . 3
3.2. Ordering of tags . . . . . . . . . . . . . . . . . . . . 4
4. Applications . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
This document provides mechanisms to advertise per-node
administrative tags in the IS-IS Link State PDU [RFC1195]. In
certain path-selection applications like for example in traffic-
engineering or LFA [RFC5286] selection there is a need to tag the
nodes based on their roles in the network and have policies to prefer
or prune a certain group of nodes.
2. Administrative Tag
For the purpose of advertising per-node administrative tags within
IS-IS, a new sub-TLV to the IS-IS Router Capability TLV-242 that is
defined in [RFC4971] is proposed. Because path selection is a
functional set which applies both to TE and non-TE applications the
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same has not added as a new sub-TLV in the Traffic Engingineering
TLVs [RFC5305].
An administrative Tag is a 32-bit integer value that can be used to
identify a group of nodes in the IS-IS domain. The new sub-TLV
specifies one or more administrative tag values. An IS-IS node
advertises the set of groups it is part of in the specific IS-IS
level. As an example, all PE-nodes may be configured with certain
tag value, whereas all P-nodes are configured with a different tag
value in.
The new sub-TLV defined will be carried inside the IS-IS Router
Capability TLV-242 (defined in [RFC4971]) in the Link State PDUs
originated by the router. Link State PDUs [ISO10589] has level-wise
(i.e. L1 or L2) flooding scope. Choosing the flooding scope to
flood the group tags are defined by the policies and is a local
matter. Once a group tag is decided in a specific level the same
will be inserted in the administrative tag sub-TLV in the Link State
PDU for the same level. Implementations should allow configuring
both a 'global' and 'per-level' admin tag. In the absence of a
specific admin tag configuration for a specific level the global
admin tag should be copied in to the LSP PDU for the same level.
3. TLV format
3.1. Per-node Admin Tag sub-TLV
The new Administrative Tag sub-TLV, like other ISIS Capability sub-
TLVs, is formatted as Type/Length/Value (TLV)triplets. Figure 1
below shows the format of the new sub-TLV.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Administrative Tag #1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Administrative Tag #2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Administrative Tag #N |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type : TBA
Length: A 8-bit field that indicates the length of the value
portion in octets and will be a multiple of 4 octets
dependent on the number of tags advertised.
Value: A sequence of multiple 4 octets defining the
administrative tags.
Figure 1: IS-IS per-node Administrative Tag sub-TLV
The 'Per-node Admin Tag' sub-TLV may be generated more than once by
an originating router. This MAY happen if a node carries more than
63 per-node admin groups and a single sub-TLV does not provide
sufficient space. As such occurence of the 'Per-node Admin Tag' sub-
TLV does not cancel previous announcements, but rather is cumulative.
3.2. Ordering of tags
The semantics of the tag order are implementation-dependent. There
is no implied meaning to the ordering of the tags that indicates a
certain operation or set of operations that need to be performed
based on the ordering.
Each tag SHOULD be treated as an independent identifier that MAY be
used in policy to perform a policy action. Whether or not tag A
precedes or succeeds tag B SHOULD not change the meaning of the tag
set.
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4. Applications
Increased deployment of Loop Free Alternates (LFA) [RFC5286] has
exposed some limitations. A recent draft on Operation management of
Loop Free Alternates [I-D.ietf-rtgwg-lfa-manageability] proposes
refinements to address those limitations. One of the proposed
refinements is to be able to group the nodes in IGP domain with
administrative tags and engineer the alternate paths based on
configured policies.
The proposal in this document helps provide the capability to
advertise group tags within IS-IS protocol and perform policy based
LFA selection. The policies configured on each node can then make
use of these tags to prefer or prune LFAs via certain group of nodes.
For a detailed list of more such applications please refer to section
5 in [I-D.hegde-ospf-node-admin-tag].
5. Security Considerations
This document does not introduce any further security issues other
than those discussed in [ISO10589] and [RFC1195].
6. IANA Considerations
IANA maintains the registry for the Router Capability sub-TLVs. IS-
IS Administrative Tags will require one new type code for the sub-TLV
defined in this document.
7. Acknowledgments
8. References
8.1. Normative References
[ISO10589]
"Intermediate system to Intermediate system intra-domain
routeing information exchange protocol for use in
conjunction with the protocol for providing the
connectionless-mode Network Service (ISO 8473), ISO/IEC
10589:2002, Second Edition.", Nov 2002.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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8.2. Informative References
[I-D.hegde-ospf-node-admin-tag]
Hegde, S., Raghuveer, H., Gredler, H., Shakir, R.,
Smirnov, A., and Z. Li, "Advertising per-node
administrative tags in OSPF", draft-hegde-ospf-node-admin-
tag-02 (work in progress), June 2014.
[I-D.ietf-rtgwg-lfa-manageability]
Litkowski, S., Decraene, B., Filsfils, C., and K. Raza,
"Operational management of Loop Free Alternates", draft-
ietf-rtgwg-lfa-manageability-00 (work in progress), May
2013.
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, December 1990.
[RFC4971] Vasseur, JP., Shen, N., and R. Aggarwal, "Intermediate
System to Intermediate System (IS-IS) Extensions for
Advertising Router Information", RFC 4971, July 2007.
[RFC5286] Atlas, A. and A. Zinin, "Basic Specification for IP Fast
Reroute: Loop-Free Alternates", RFC 5286, September 2008.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, October 2008.
Authors' Addresses
Pushpasis Sarkar (editor)
Juniper Networks, Inc.
Electra, Exora Business Park
Bangalore, KA 560103
India
Email: psarkar@juniper.net
Hannes Gredler
Juniper Networks, Inc.
1194 N. Mathilda Ave.
Sunnyvale, CA 94089
US
Email: hannes@juniper.net
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Shraddha Hegde
Juniper Networks, Inc.
Electra, Exora Business Park
Bangalore, KA 560103
India
Email: shraddha@juniper.net
Stephane Litkowski
Orange
Email: stephane.litkowski@orange.com
Bruno Decraene
Orange
Email: bruno.decraene@orange.com
Li Zhenbin
Huawei Technologies
Huawei Bld. No.156 Beiqing Rd
Beijing, KA 100095
China
Email: lizhenbin@huawei.com
Harish Raghuveer
Email: hraghuveer@juniper.net
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