draft-ietf-isis-purge-tlv-00.txt   draft-ietf-isis-purge-tlv-01.txt 
IS-IS Working Group F. Wei IS-IS Working Group F. Wei
Internet-Draft Y. Qin Internet-Draft Y. Qin
Updates: 5304, 5310 Z. Li Updates: 5301, 5304, 5310 Z. Li
(if approved) China Mobile (if approved) China Mobile
Intended status: Standards Track T. Li Intended status: Standards Track T. Li
Expires: October 21, 2010 Cisco Systems, Inc. Expires: November 15, 2010 Cisco Systems, Inc.
J. Dong J. Dong
Huawei Technologies Huawei Technologies
April 19, 2010 May 14, 2010
Purge Originator Identification TLV for IS-IS Purge Originator Identification TLV for IS-IS
draft-ietf-isis-purge-tlv-00 draft-ietf-isis-purge-tlv-01
Abstract Abstract
At present an IS-IS purge does not contain any information At present an IS-IS purge does not contain any information
identifying the Intermediate System (IS) that generates the purge. identifying the Intermediate System (IS) that generates the purge.
This makes it difficult to locate the source IS. This makes it difficult to locate the source IS.
To address this issue, this document defines a TLV to be added to 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 purges to record the system ID of the IS generating it. Since normal
LSP flooding does not change LSP contents, this TLV should propagate LSP flooding does not change LSP contents, this TLV should propagate
skipping to change at page 1, line 42 skipping to change at page 1, line 42
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Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Language . . . . . . . . . . . . . . . . . . . . . 3
3. Cases to Generate Purge Packet . . . . . . . . . . . . . . . . 3 3. The Purge Originator Identification TLV . . . . . . . . . . . . 3
4. The Purge Originator Identification TLV . . . . . . . . . . . . 4 4. Using the Dynamic Hostname TLV in Purges . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 6. Functional Changes . . . . . . . . . . . . . . . . . . . . . . 4
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 4 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
8. Normative References . . . . . . . . . . . . . . . . . . . . . 5 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5 9. Normative References . . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
The IS-IS [ISO 10589] routing protocol has been widely used in large- The IS-IS [ISO 10589] routing protocol has been widely used in large-
scale IP networks because of its strong scalability and fast scale IP networks because of its strong scalability and fast
convergence. convergence.
The IS-IS protocol floods purges throughout an area, regardless of The IS-IS protocol floods purges throughout an area, regardless of
which IS initiated the purge. If a network operator would like to which IS initiated the purge. If a network operator would like to
investigate the cause of the purge, it is difficult to determine the 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 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 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 document defines a TLV to be added to purges to record the system ID
of the IS generating the purge. 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 2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
3. Cases to Generate Purge Packet 3. The Purge Originator Identification TLV
In IS-IS there are three legitimate reasons for an IS to generate a
purge:
1. An IS purges its own LSP. 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.
2. A LSP owned by another IS ages out. 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.
3. A new DIS is elected. The Purge Originator Identification TLV is defined as:
Field experience has observed serveral other circumstances where an CODE - XX (to be assigned)
IS can improperly generate a purge:
1. An implementation misunderstanding [ISO 10589] or predating TC1 LENGTH - total length of the value field.
generates a purge when it receives a corrupted LSP.
2. An implementation with bugs tries to purge one of its LSPs and VALUE -
makes a truly egregious mistake. Number of system IDs carried in this TLV (1 octet) -- Only the
values 1 and 2 are defined.
3. An implementation fails to retain the LSP header after purging System ID of the Intermediate System that inserted this TLV.
while flooding is still in progress.
4. The Purge Originator Identification TLV The system ID of the Intermediate System that the purge was
received from. (optional)
This document defines a TLV to be included in purges. This TLV 4. Using the Dynamic Hostname TLV in Purges
carries the system ID of the IS generating the purge.
This allows ISs receiving purges to log the system ID of the This document also extends the use of the Dynamic hostname TLV (type
originator. This makes it much easier for the network administrator 137) [RFC5301]. This TLV MAY also be included in purges. This will
to locate the origin of the purge and thus the cause of the purge. further aid in the rapid identification of the system that generated
Similarly, this TLV is helpful to developers in lab situations. the purge.
The Purge Originator Identification TLV is defined as: Implementations SHOULD include the Purge Originator Identification
TLV in addition to the Dynamic hostname TLV.
CODE - XX (to be assigned) 5. Security Considerations
LENGTH - total length of the value field. 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.
VALUE - System ID of the Intermediate System that initiated the Legacy systems that implement [RFC5304] or [RFC5310] MUST discard
purge. purges with these additional TLVs. This is not thought to be a
significant operational issue as the loss of purges is typically not
critical.
5. Security Considerations 6. Functional Changes
If the proposed TLV is used in conjunction with IS-IS authentication This document amends the behavior specified in [RFC5301], [RFC5304]
mechanisms [RFC5304][RFC5310], the purge LSP is constructed by and [RFC5310]. ISs that receive purges with the Purge Originator
removing the original contents of the LSP, leaving only the LSP Identification TLV or the Dynamic hostname TLV with valid
header, adding the Purge Originator Identification TLV and then authentication MUST NOT discard the PDU and SHOULD process it
adding the IS-IS authentication TLV. This document amends the normally. ISs that receive purges with the Purge Originator
behavior specified in [RFC5304] and [RFC5310]. 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.
6. IANA Considerations 7. IANA Considerations
RFC EDITOR NOTE: This section to be removed upon publication. RFC EDITOR NOTE: This section to be removed upon publication.
This document requests that IANA assign a code point for this TLV This document requests that IANA assign a code point for this TLV
from the IS-IS 'TLV Codepoints Registry'. from the IS-IS 'TLV Codepoints Registry'.
7. Acknowledgments 8. Acknowledgments
Many thanks to Adrian Farrel and Daniel King for your comments to Many thanks to Adrian Farrel and Daniel King for your comments to
improve this document and move it forward. improve this document and move it forward.
The first version of this document was mainly composed by Lianyuan The first version of this document was mainly composed by Lianyuan
Li. Li.
Acknowledgments to the discussion in the mailing list. Some Acknowledgments to the discussion in the mailing list. Some
impovements of this document are based on the discussion. improvements of this document are based on the discussion.
8. Normative References 9. Normative References
[ISO 10589] [ISO 10589]
ISO, "Intermediate system to Intermediate system routeing ISO, "Intermediate system to Intermediate system routeing
information exchange protocol for use in conjunction with information exchange protocol for use in conjunction with
the Protocol for providing the Connectionless-mode Network the Protocol for providing the Connectionless-mode Network
Service (ISO 8473)", ISO/IEC 10589:2002. 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 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. 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 [RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic
Authentication", RFC 5304, October 2008. Authentication", RFC 5304, October 2008.
[RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., [RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
and M. Fanto, "IS-IS Generic Cryptographic and M. Fanto, "IS-IS Generic Cryptographic
Authentication", RFC 5310, February 2009. Authentication", RFC 5310, February 2009.
Authors' Addresses Authors' Addresses
Fang Wei Fang Wei
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