draft-ietf-idr-ext-opt-param-07.txt   draft-ietf-idr-ext-opt-param-08.txt 
Internet Engineering Task Force E. Chen Internet Engineering Task Force E. Chen
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Updates: 4271 (if approved) J. Scudder Updates: 4271 (if approved) J. Scudder
Intended status: Standards Track Juniper Networks Intended status: Standards Track Juniper Networks
Expires: February 1, 2020 July 31, 2019 Expires: May 21, 2020 November 18, 2019
Extended Optional Parameters Length for BGP OPEN Message Extended Optional Parameters Length for BGP OPEN Message
draft-ietf-idr-ext-opt-param-07 draft-ietf-idr-ext-opt-param-08
Abstract Abstract
The Optional Parameters in the BGP OPEN message as defined in the The Optional Parameters in the BGP OPEN message as defined in the
base BGP specification are limited to 255 octets due to a one-octet base BGP specification are limited to 255 octets due to a one-octet
length field. BGP Capabilities are carried in this field and may length field. BGP Capabilities are carried in this field and may
foreseeably exceed 255 octets in the future, leading to concern about foreseeably exceed 255 octets in the future, leading to concern about
this limitation. this limitation.
In this document we update RFC 4271 by extending the BGP OPEN length In this document we update RFC 4271 by extending, in a backward-
field in a backward-compatible manner. The Parameter Length field of compatible manner, the length of the Optional Parameters in the BGP
individual Optional Parameters is also extended. OPEN. The Parameter Length field of individual Optional Parameters
is also extended.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 https://datatracker.ietf.org/drafts/current/. Drafts is at https://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 1, 2020. This Internet-Draft will expire on May 21, 2020.
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.
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
(https://trustee.ietf.org/license-info) in effect on the date of (https://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
skipping to change at page 2, line 19 skipping to change at page 2, line 20
1. Introduction 1. Introduction
The Optional Parameters Length field in the BGP OPEN message is The Optional Parameters Length field in the BGP OPEN message is
defined in the base BGP specification [RFC4271] as one octet, thus defined in the base BGP specification [RFC4271] as one octet, thus
limiting the Optional Parameters field in the OPEN message to 255 limiting the Optional Parameters field in the OPEN message to 255
octets. Since BGP Capabilities [RFC5492] are carried in the Optional octets. Since BGP Capabilities [RFC5492] are carried in the Optional
Parameters field, and new BGP capabilities continue to be introduced, Parameters field, and new BGP capabilities continue to be introduced,
the limitation is a concern for BGP development. the limitation is a concern for BGP development.
In this document we update [RFC4271] by extending the BGP OPEN length In this document we update [RFC4271] by extending, in a backward-
field in a backward-compatible manner. The Parameter Length field of compatible manner, the length of the Optional Parameters in BGP OPEN.
individual Optional Parameters is also extended. This is done by This is done by using Optional Parameter Type 255 as a distinguished
using Optional Parameter Type 255 as a distinguished value, that value, that indicates an extended Optional Parameters Length field
indicates an extended Optional Parameters Length field follows. In follows. In this case the Parameter Length field of the individual
this case the Parameter Length field of the Optional Parameters in Optional Parameters in the BGP OPEN message is also extended.
the BGP OPEN message is also extended.
1.1. Requirements Language 1.1. 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 RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
2. Protocol Extensions 2. Protocol Extensions
This document reserves Optional Parameter Type code 255 as the This document reserves Optional Parameter Type code 255 as the
skipping to change at page 4, line 41 skipping to change at page 4, line 41
speaker which has not been upgraded to support this specification may speaker which has not been upgraded to support this specification may
legitimately send Optional Parameters whose length equals exactly legitimately send Optional Parameters whose length equals exactly
255, thus the Optional Parameters Length field alone is insufficient 255, thus the Optional Parameters Length field alone is insufficient
as an indicator. However, such a speaker would never legitimately as an indicator. However, such a speaker would never legitimately
send an Optional Parameter whose type code is 255, since that value send an Optional Parameter whose type code is 255, since that value
has been reserved by this specification. has been reserved by this specification.
The choice to mandate that when the extended encoding is in use, the The choice to mandate that when the extended encoding is in use, the
(non-extended) Optional Parameters Length field must be 255 was made (non-extended) Optional Parameters Length field must be 255 was made
for backward compatibility with implementations of earlier versions for backward compatibility with implementations of earlier versions
of this specification. In any event the value 0 MUST NOT be used in of this specification. When the extended encoding is in use, the
this field since the presence of that value could have the effect of value 0 MUST NOT be used in that field since the presence of that
causing a message parser to never inspect the following octet. value could have the effect of causing a message parser to never
inspect the following octet.
3. Errors 3. Errors
If a BGP speaker supporting this specification (a "new speaker") is If a BGP speaker supporting this specification (a "new speaker") is
peering with one which does not (an "old speaker") no peering with one which does not (an "old speaker") no
interoperability issues arise unless the new speaker needs to encode interoperability issues arise unless the new speaker needs to encode
Optional Parameters whose length exceeds 255. In that case, it will Optional Parameters whose length exceeds 255. In that case, it will
transmit an OPEN message which the old speaker will interpret as transmit an OPEN message which the old speaker will interpret as
containing an Optional Parameter with type code 255. Since by containing an Optional Parameter with type code 255. Since by
definition the old speaker will not recognize that type code, the old definition the old speaker will not recognize that type code, the old
 End of changes. 6 change blocks. 
16 lines changed or deleted 17 lines changed or added

This html diff was produced by rfcdiff 1.47. The latest version is available from http://tools.ietf.org/tools/rfcdiff/