draft-ietf-idr-ext-opt-param-12.txt   draft-ietf-idr-ext-opt-param-13.txt 
Internet Engineering Task Force E. Chen IDR E. Chen
Internet-Draft Palo Alto Networks Internet-Draft Palo Alto Networks
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: October 23, 2021 April 21, 2021 Expires: October 24, 2021 April 22, 2021
Extended Optional Parameters Length for BGP OPEN Message Extended Optional Parameters Length for BGP OPEN Message
draft-ietf-idr-ext-opt-param-12 draft-ietf-idr-ext-opt-param-13
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.
This document updates RFC 4271 by extending, in a backward-compatible This document updates RFC 4271 by extending, in a backward-compatible
skipping to change at page 1, line 40 skipping to change at page 1, line 40
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 October 23, 2021. This Internet-Draft will expire on October 24, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 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
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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.
This document updates [RFC4271] by extending, in a backward- This document updates [RFC4271] by extending, in a backward-
compatible manner, the length of the Optional Parameters in BGP OPEN. compatible manner, the length of the Optional Parameters in BGP OPEN.
This is done by using Optional Parameter Type 255 as a distinguished This is done by using Optional Parameter Type 255 as a distinguished
value, that indicates an extended Optional Parameters Length field value, that indicates an extended Optional Parameters Length field
follows. In this case the Parameter Length field of the individual follows and that the parsing of the BGP OPEN should be modified
Optional Parameters in the BGP OPEN message is also extended. according to these procedures. In this case the Parameter Length
field of the individual Optional Parameters in 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", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2. Update to RFC 4271 2. Update to RFC 4271
This document reserves Optional Parameter Type code 255 as the This document reserves Optional Parameter Type code 255 as the
"Extended Length" type code. "Extended Length" type code.
In the event that the length of Optional Parameters in the BGP OPEN In the event that the length of Optional Parameters in the BGP OPEN
message does not exceed 255, the encodings of the base BGP message does not exceed 255, the encodings of the base BGP
specification [RFC4271] MUST be used without alteration. (However, specification [RFC4271] SHOULD be used without alteration.
an implementation MUST accept an OPEN message that uses the encoding Configuration MAY override this to force the extended format to be
of this specification even if the length of Optional Parameters is used in all cases; this might be used, for example to test that a
255 or less.) peer supports this specification. (In any case, an implementation
MUST accept an OPEN message that uses the encoding of this
specification even if the length of Optional Parameters is 255 or
less.)
However, if the length of Optional Parameters in the BGP OPEN message However, if the length of Optional Parameters in the BGP OPEN message
does exceed 255, the OPEN message MUST be encoded according to the does exceed 255, the OPEN message MUST be encoded according to the
procedure below. procedure below.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
| Version | | Version |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| My Autonomous System | | My Autonomous System |
 End of changes. 6 change blocks. 
11 lines changed or deleted 15 lines changed or added

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