IS-IS for IP Internets P. Sarkar, Ed.
Internet-Draft H. Gredler
Intended status: Standards Track S. Hegde
Expires: April 24, 2014 H. Raghuveer
Juniper Networks, Inc.
S. Litkowski
B. Decraene
Orange
October 21, 2013
Advertising Per-node Admin Tags in IS-IS
draft-psarkar-isis-node-admin-tag-00
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 24, 2014.
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Copyright Notice
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Administrative Tag TLV . . . . . . . . . . . . . . . . . . . 2
3. TLV format . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Per-node Admin Tag TLV . . . . . . . . . . . . . . . . . 3
3.2. Ordering of tags . . . . . . . . . . . . . . . . . . . . 4
4. Applications . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 4
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
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 TLV
For the purpose of advertising per-node administrative tags within
IS-IS, a new TLV is proposed. Because path selection is a functional
set which applies both to TE and non-TE applications the same has not
added as a new sub-TLV in the Traffic Engingineering TLVs [RFC5305].
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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 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 TLV defined will be carried as a new TLV 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 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 TLV
The new Administrative Tag TLV, like other ISIS TLVs, is formatted as
Type/Length/Value (TLV)triplets. Figure 1 below shows the format of
the new TLV.
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.
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Figure 1: IS-IS per-node Administrative Tag TLV
The 'Per-node Admin Tag' 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 TLV does not provide sufficient
space. As such occurence of the 'Per-node Admin Tag' TLV does not
cancel previous TLV 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.
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.
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 TLVs. IS-IS Administrative Tags
will require one new type code for the TLV defined in this document.
7. Acknowledgments
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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.
8.2. Informative References
[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.
[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
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Hannes Gredler
Juniper Networks, Inc.
1194 N. Mathilda Ave.
Sunnyvale, CA 94089
US
Email: hannes@juniper.net
Shraddha Hegde
Juniper Networks, Inc.
Electra, Exora Business Park
Bangalore, KA 560103
India
Email: shraddha@juniper.net
Harish Raghuveer
Juniper Networks, Inc.
Electra, Exora Business Park
Bangalore, KA 560103
India
Email: hraghuveer@juniper.net
Stephane Litkowski
Orange
Email: stephane.litkowski@orange.com
Bruno Decraene
Orange
Email: bruno.decraene@orange.com
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