draft-ietf-isis-rfc4971bis-03.txt   draft-ietf-isis-rfc4971bis-04.txt 
Networking Working Group L. Ginsberg Networking Working Group L. Ginsberg
Internet-Draft S. Previdi Internet-Draft S. Previdi
Obsoletes: 4971 (if approved) Cisco Systems Obsoletes: 4971 (if approved) Cisco Systems
Intended status: Standards Track M. Chen Intended status: Standards Track M. Chen
Expires: February 16, 2017 Huawei Technologies Co., Ltd Expires: February 19, 2017 Huawei Technologies Co., Ltd
August 15, 2016 August 18, 2016
IS-IS Extensions for Advertising Router Info IS-IS Extensions for Advertising Router Info
draft-ietf-isis-rfc4971bis-03.txt draft-ietf-isis-rfc4971bis-04.txt
Abstract Abstract
This document defines a new optional Intermediate System to This document defines a new optional Intermediate System to
Intermediate System (IS-IS) TLV named CAPABILITY, formed of multiple Intermediate System (IS-IS) TLV named CAPABILITY, formed of multiple
sub-TLVs, which allows a router to announce its capabilities within sub-TLVs, which allows a router to announce its capabilities within
an IS-IS level or the entire routing domain. This document obsoletes an IS-IS level or the entire routing domain. This document obsoletes
RFC 4971. RFC 4971.
Requirements Language Requirements Language
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 16, 2017. This Internet-Draft will expire on February 19, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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replaces. Where this is not possible, the two affected LSP fragments replaces. Where this is not possible, the two affected LSP fragments
should be flooded as an atomic action. should be flooded as an atomic action.
Systems that receive an update to an existing CAPABILITY TLV can Systems that receive an update to an existing CAPABILITY TLV can
minimize the potential disruption associated with the update by minimize the potential disruption associated with the update by
employing a holddown time prior to processing the update so as to employing a holddown time prior to processing the update so as to
allow for the receipt of multiple LSP fragments associated with the allow for the receipt of multiple LSP fragments associated with the
same update prior to beginning processing. same update prior to beginning processing.
Where a receiving system has two copies of a CAPABILITY TLV from the Where a receiving system has two copies of a CAPABILITY TLV from the
same system that have different settings for a given attribute, the same system that have conflicting information for a given sub-TLV,
procedure used to choose which copy shall be used is undefined. the procedure used to choose which copy shall be used is undefined.
4. Interoperability with Routers Not Supporting the Capability TLV 4. Interoperability with Routers Not Supporting the Capability TLV
Routers that do not support the Router CAPABILITY TLV MUST silently Routers that do not support the Router CAPABILITY TLV MUST silently
ignore the TLV(s) and continue processing other TLVs in the same LSP. ignore the TLV(s) and continue processing other TLVs in the same LSP.
Routers that do not support specific sub-TLVs carried within a Router Routers that do not support specific sub-TLVs carried within a Router
CAPABILITY TLV MUST silently ignore the unsupported sub-TLVs and CAPABILITY TLV MUST silently ignore the unsupported sub-TLVs and
continue processing those sub-TLVs that are supported in the Router continue processing those sub-TLVs that are supported in the Router
CAPABILITY TLV. How partial support may impact the operation of the CAPABILITY TLV. How partial support may impact the operation of the
capabilities advertised within the Router CAPABILITY TLV is outside capabilities advertised within the Router CAPABILITY TLV is outside
the scope of this document. the scope of this document.
In order for Router CAPABILITY TLVs with domain-wide scope originated In order for Router CAPABILITY TLVs with domain-wide scope originated
by L1 Routers to be flooded across the entire domain, at least one by L1 Routers to be flooded across the entire domain, at least one
L1/L2 Router in every area of the domain MUST support the Router L1/L2 Router in every area of the domain MUST support the Router
CAPABILITY TLV. CAPABILITY TLV.
If leaking of the CAPABILITY TLV is required, the entire CAPABILITY If leaking of the CAPABILITY TLV is required, the entire CAPABILITY
TLV MUST be leaked into another level without change even though it TLV MUST be leaked into another level without change (except for
may contain some sub-TLVs which are unsupported by the Router doing changes to the TLV flags as noted in Section 2) even though it may
the leaking. contain some sub-TLVs which are unsupported by the Router doing the
leaking.
5. Security Considerations 5. Security Considerations
Any new security issues raised by the procedures in this document Any new security issues raised by the procedures in this document
depend upon the opportunity for LSPs to be snooped and modified, the depend upon the opportunity for LSPs to be snooped and modified, the
ease/difficulty of which has not been altered. As the LSPs may now ease/difficulty of which has not been altered. As the LSPs may now
contain additional information regarding router capabilities, this contain additional information regarding router capabilities, this
new information would also become available to an attacker. new information would also become available to an attacker.
Specifications based on this mechanism need to describe the security Specifications based on this mechanism need to describe the security
considerations around the disclosure and modification of their considerations around the disclosure and modification of their
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