< draft-ginsberg-lsr-isis-invalid-tlv-02.txt   draft-ginsberg-lsr-isis-invalid-tlv-03.txt >
LSR Working Group L. Ginsberg LSR Working Group L. Ginsberg
Internet-Draft P. Wells Internet-Draft P. Wells
Updates: 3563 5305 6232 6233 (if Cisco Systems Updates: 3563 5305 6232 6233 (if Cisco Systems
approved) T. Li approved) T. Li
Intended status: Standards Track Arista Networks Intended status: Standards Track Arista Networks
Expires: September 28, 2019 T. Przygienda Expires: October 5, 2019 T. Przygienda
S. Hegde S. Hegde
Juniper Networks, Inc. Juniper Networks, Inc.
March 27, 2019 April 3, 2019
Invalid TLV Handling in IS-IS Invalid TLV Handling in IS-IS
draft-ginsberg-lsr-isis-invalid-tlv-02 draft-ginsberg-lsr-isis-invalid-tlv-03
Abstract Abstract
Key to the extensibility of the Intermediate System to Intermediate Key to the extensibility of the Intermediate System to Intermediate
System (IS-IS) protocol has been the handling of unsupported and/or System (IS-IS) protocol has been the handling of unsupported and/or
invalid Type/Length/Value (TLV) tuples. Although there are explicit invalid Type/Length/Value (TLV) tuples. Although there are explicit
statements in existing specifications, deployment experience has statements in existing specifications, deployment experience has
shown that there are inconsistencies in the behavior when a TLV which shown that there are inconsistencies in the behavior when a TLV which
is disallowed in a particular Protocol Data Unit (PDU) is received. is disallowed in a particular Protocol Data Unit (PDU) is received.
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This Internet-Draft will expire on September 28, 2019. This Internet-Draft will expire on October 5, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. TLV Codepoints Registry . . . . . . . . . . . . . . . . . . . 3 2. TLV Codepoints Registry . . . . . . . . . . . . . . . . . . . 3
3. TLV Acceptance in PDUs . . . . . . . . . . . . . . . . . . . 4 3. TLV Acceptance in PDUs . . . . . . . . . . . . . . . . . . . 4
3.1. Handling of Disallowed TLVs in Received PDUs . . . . . . 4 3.1. Handling of Disallowed TLVs in Received PDUs other than
3.2. Special Handling of Disallowed TLVs in Received Purges . 4 LSP Purges . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Special Handling of Disallowed TLVs in Received LSP
Purges . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.3. Applicability to sub-TLVs . . . . . . . . . . . . . . . . 5 3.3. Applicability to sub-TLVs . . . . . . . . . . . . . . . . 5
3.4. Correction to POI TLV Registry Entry . . . . . . . . . . 5 3.4. Correction to POI TLV Registry Entry . . . . . . . . . . 5
4. TLV Validation and LSP Acceptance . . . . . . . . . . . . . . 5 4. TLV Validation and LSP Acceptance . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . 6 8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . 8 8.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
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If "N" is entered in a column it means the TLV is NOT allowed in the If "N" is entered in a column it means the TLV is NOT allowed in the
corresponding PDU type. corresponding PDU type.
3. TLV Acceptance in PDUs 3. TLV Acceptance in PDUs
This section describes the correct behavior when a PDU is received This section describes the correct behavior when a PDU is received
which contains a TLV which is specified as disallowed in the TLV which contains a TLV which is specified as disallowed in the TLV
Codepoints Registry. Codepoints Registry.
3.1. Handling of Disallowed TLVs in Received PDUs 3.1. Handling of Disallowed TLVs in Received PDUs other than LSP Purges
[ISO10589] defines the behavior required when a PDU is received [ISO10589] defines the behavior required when a PDU is received
containing a TLV which is "not recognised". It states (see Sections containing a TLV which is "not recognised". It states (see Sections
9.3 - 9.13): 9.3 - 9.13):
"Any codes in a received PDU that are not recognised shall be "Any codes in a received PDU that are not recognised shall be
ignored." ignored."
This is the model to be followed when a TLV is received which is This is the model to be followed when a TLV is received which is
disallowed. Therefore TLVs in a PDU which are disallowed MUST be disallowed. Therefore TLVs in a PDU (other than LSP purges) which
ignored and MUST NOT cause the PDU itself to be rejected by the are disallowed MUST be ignored and MUST NOT cause the PDU itself to
receiving IS. be rejected by the receiving IS.
3.2. Special Handling of Disallowed TLVs in Received Purges 3.2. Special Handling of Disallowed TLVs in Received LSP Purges
When purging LSPs [ISO10589] recommends (but does not require) the When purging LSPs [ISO10589] recommends (but does not require) the
body of the LSP (i.e., all TLVs) be removed before generating the body of the LSP (i.e., all TLVs) be removed before generating the
purge. LSP purges which have TLVs in the body are accepted though purge. LSP purges which have TLVs in the body are accepted though
any TLVs which are present "MUST" be ignored. any TLVs which are present "MUST" be ignored.
When cryptographic authentication [RFC5304] was introduced, this When cryptographic authentication [RFC5304] was introduced, this
looseness when processing received purges had to be addressed in looseness when processing received purges had to be addressed in
order to prevent attackers from being able to initiate a purge order to prevent attackers from being able to initiate a purge
without having access to the authentication key. [RFC5304] therefore without having access to the authentication key. [RFC5304] therefore
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