IS-IS Working Group F. Wei
Internet-Draft Y. Qin
Updates: 5301, 5304, 5310 Z. Li
(if approved) China Mobile
Intended status: Standards Track T. Li
Expires: December 9, 2010 Cisco Systems, Inc.
J. Dong
Huawei Technologies
June 7, 2010
Purge Originator Identification TLV for IS-IS
draft-ietf-isis-purge-tlv-02
Abstract
At present an IS-IS purge does not contain any information
identifying the Intermediate System (IS) that generates the purge.
This makes it difficult to locate the source IS.
To address this issue, this document defines a TLV to be added to
purges to record the system ID of the IS generating it. Since normal
LSP flooding does not change LSP contents, this TLV should propagate
with the purge.
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 December 9, 2010.
Copyright Notice
Copyright (c) 2010 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
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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
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . . 3
3. The Purge Originator Identification TLV . . . . . . . . . . . . 3
4. Using the Dynamic Hostname TLV in Purges . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
6. Functional Changes . . . . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5
9. Normative References . . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6
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1. Introduction
The IS-IS [ISO 10589] routing protocol has been widely used in large-
scale IP networks because of its strong scalability and fast
convergence.
The IS-IS protocol floods purges throughout an area, regardless of
which IS initiated the purge. If a network operator would like to
investigate the cause of the purge, it is difficult to determine the
origin of the purge. At present the IS-IS protocol has no mechanism
to locate the originator of a purge. To address this problem, this
document defines a TLV to be added to purges to record the system ID
of the IS generating the purge.
Field experience has observed several circumstances where an IS can
improperly generate a purge. These are all due to implementation
deficiencies or implementations that predate [ISO TC1] and generate a
purge when they receive a corrupted LSP.
2. 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 [RFC2119].
3. The Purge Originator Identification TLV
This document defines a TLV to be included in purges. This TLV
carries the system ID of the IS generating the purge, or, in a proxy
mode, carries the system ID of the IS that first saw the purge and
inserted this TLV, as well as the system ID of the system that it
received the purge from.
This allows ISs receiving purges to log the system ID of the
originator, or the upstream source of the purge. This makes it much
easier for the network administrator to locate the origin of the
purge and thus the cause of the purge. Similarly, this TLV is
helpful to developers in lab situations.
The Purge Originator Identification TLV is defined as:
CODE - 13
LENGTH - total length of the value field.
VALUE -
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Number of system IDs carried in this TLV (1 octet) -- Only the
values 1 and 2 are defined.
System ID of the Intermediate System that inserted this TLV.
The system ID of the Intermediate System that the purge was
received from. (optional)
4. Using the Dynamic Hostname TLV in Purges
This document also extends the use of the Dynamic hostname TLV (type
137) [RFC5301]. This TLV MAY also be included in purges. This will
further aid in the rapid identification of the system that generated
the purge.
Implementations SHOULD include the Purge Originator Identification
TLV in addition to the Dynamic hostname TLV.
5. Security Considerations
If the proposed TLV or the Dynamic hostname TLV is used in
conjunction with IS-IS authentication mechanisms [RFC5304][RFC5310],
the purge LSP is constructed as follows. First, the original
contents of the LSP are removed, leaving only the LSP header, then
the Purge Originator Identification TLV and/or the Dynamic hostname
TLV are added, and then the IS-IS authentication TLV is added.
Legacy systems that implement [RFC5304] or [RFC5310] MUST discard
purges with these additional TLVs. This is not thought to be a
significant operational issue as the loss of purges is typically not
critical.
6. Functional Changes
This document amends the behavior specified in [RFC5301], [RFC5304]
and [RFC5310]. ISs that receive purges with the Purge Originator
Identification TLV or the Dynamic hostname TLV with valid
authentication MUST NOT discard the PDU and SHOULD process it
normally. ISs that receive purges with the Purge Originator
Identification TLV or the Dynamic hostname TLV MUST be accepted and
processed as a normal purge. The Purge Originator Identification TLV
or Dynamic hostname TLV MUST NOT be removed from the purge prior to
propagation. If multiple purges are received for the same LSP
fragment, then the implementation MAY propagate any one of the
purges.
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7. IANA Considerations
RFC EDITOR NOTE: This section to be removed upon publication.
This document requests that IANA assign a code point for this TLV
from the IS-IS 'TLV Codepoints Registry'.
8. Acknowledgments
Many thanks to Adrian Farrel and Daniel King for your comments to
improve this document and move it forward.
The first version of this document was mainly composed by Lianyuan
Li.
Acknowledgments to the discussion in the mailing list. Some
improvements of this document are based on the discussion.
9. Normative References
[ISO 10589]
ISO, "Intermediate system to Intermediate system routeing
information exchange protocol for use in conjunction with
the Protocol for providing the Connectionless-mode Network
Service (ISO 8473)", ISO/IEC 10589:2002.
[ISO TC1] ISO, "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) --
Technical Corrigendum 1", ISO/IEC 10589:1992/ Cor.1:1993.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5301] McPherson, D. and N. Shen, "Dynamic Hostname Exchange
Mechanism for IS-IS", RFC 5301, October 2008.
[RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic
Authentication", RFC 5304, October 2008.
[RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
and M. Fanto, "IS-IS Generic Cryptographic
Authentication", RFC 5310, February 2009.
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Authors' Addresses
Fang Wei
China Mobile
No. 29, Financial Street, Xicheng District
Beijing 100032
P.R. China
Email: weifang@chinamobile.com
Yue Qin
China Mobile
No. 29, Financial Street, Xicheng District
Beijing 100032
P.R. China
Email: qinyue@chinamobile.com
Zhenqiang Li
China Mobile
Unit2, Dacheng Plaza, No. 28 Xuanwumenxi Ave, Xuanwu District
Beijing 100053
P.R. China
Email: lizhenqiang@chinamobile.com
Tony Li
Cisco Systems, Inc.
170 W. Tasman Dr.
San Jose, CA 95134
USA
Email: tony.li@tony.li
Jie Dong
Huawei Technologies
KuiKe Building, No.9 Xinxi Rd., Haidian District
Beijing 100085
P.R. China
Email: dongjie_dj@huawei.com
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