Re: [Idr] Mirja Kühlewind's No Objection on draft-ietf-idr-bgp-extended-messages-33: (with COMMENT)

Enke:

Your point is that a BGP speaker is defined in RFC5492 and a BGP listener is not? 

Cheerily, Susan Hares 

-----Original Message-----
From: Idr [mailto:idr-bounces@ietf.org] On Behalf Of Enke Chen (enkechen)
Sent: Tuesday, July 30, 2019 9:53 PM
To: Randy Bush; Alvaro Retana
Cc: idr@ietf.org; idr-chairs@ietf.org; draft-ietf-idr-bgp-extended-messages@ietf.org; The IESG; "Mirja Kühlewind via Datatracker"
Subject: Re: [Idr] Mirja Kühlewind's No Objection on draft-ietf-idr-bgp-extended-messages-33: (with COMMENT)

Hi, Randy and Alvaro:

Here is a patch that would clarify the capability definition, the issue that I brought up before.
It also include changing "BGP listener" to "BGP speaker" in two places.

Thanks.  -- Enke

*** bgp-large-msg-34.txt.orig	Tue Jul 30 18:24:32 2019
--- bgp-large-msg-34.txt	Tue Jul 30 18:34:07 2019
*************** Internet-Draft      Extended Message sup
*** 120,148 ****
     defined with Capability code 6 and Capability length 0.

     To advertise the BGP Extended Message Capability to a peer, a BGP
     speaker uses BGP Capabilities Advertisement [RFC5492].  By
     advertising the BGP Extended Message Capability to a peer, a BGP
!    speaker conveys that it is able to send, receive, and properly
     handle, see Section 4, BGP Extended Messages.

-    A peer which does not advertise this capability MUST NOT send BGP
-    Extended Messages, and BGP Extended Messages MUST NOT be sent to it.
- 
     Peers that wish to use the BGP Extended Message capability MUST
     support Error Handling for BGP UPDATE Messages per [RFC7606].

  4.  Operation

     The Extended Message Capability applies to all messages except for
     the OPEN and KEEPALIVE messages.  The former exception is to reduce
     the complexity of providing backward compatibility.

!    A BGP speaker that is capable of sending and receiving BGP Extended
     Messages SHOULD advertise the BGP Extended Message Capability to its
     peers using BGP Capabilities Advertisement [RFC5492].  A BGP speaker
!    MAY send Extended Messages to a peer if the Extended Message
     Capability was received from that peer.

     An implementation that advertises the BGP Extended Message capability
     MUST be capable of receiving a message with a Length up to and
     including 65,535 octets.
--- 120,145 ----
     defined with Capability code 6 and Capability length 0.

     To advertise the BGP Extended Message Capability to a peer, a BGP
     speaker uses BGP Capabilities Advertisement [RFC5492].  By
     advertising the BGP Extended Message Capability to a peer, a BGP
!    speaker conveys that it is able to receive, and properly
     handle, see Section 4, BGP Extended Messages.

     Peers that wish to use the BGP Extended Message capability MUST
     support Error Handling for BGP UPDATE Messages per [RFC7606].

  4.  Operation

     The Extended Message Capability applies to all messages except for
     the OPEN and KEEPALIVE messages.  The former exception is to reduce
     the complexity of providing backward compatibility.

!    A BGP speaker that is capable of receiving BGP Extended
     Messages SHOULD advertise the BGP Extended Message Capability to its
     peers using BGP Capabilities Advertisement [RFC5492].  A BGP speaker
!    MAY send Extended Messages to a peer only if the Extended Message
     Capability was received from that peer.

     An implementation that advertises the BGP Extended Message capability
     MUST be capable of receiving a message with a Length up to and
     including 65,535 octets.
*************** Internet-Draft      Extended Message sup
*** 157,168 ****
     4,096 octet pre- Extended Message limit, so as not to require
     downstream routers to decompose for peers that do not support
     Extended Messages.  See Section 8.

     If a BGP message with a Length greater than 4,096 octets is received
!    by a BGP listener who has not advertised the Extended Message
!    Capability, the listener will generate a NOTIFICATION with the Error
     Subcode set to Bad Message Length ([RFC4271] Sec 6.1).

  Bush, et al.            Expires January 31, 2020                [Page 3]
--- 154,165 ----
     4,096 octet pre- Extended Message limit, so as not to require
     downstream routers to decompose for peers that do not support
     Extended Messages.  See Section 8.

     If a BGP message with a Length greater than 4,096 octets is received
!    by a BGP speaker who has not advertised the Extended Message
!    Capability, the speaker will generate a NOTIFICATION with the Error
     Subcode set to Bad Message Length ([RFC4271] Sec 6.1).

  Bush, et al.            Expires January 31, 2020                [Page 3]
*************** Internet-Draft      Extended Message sup
*** 175,190 ****
     speakers which may not support Extended Messages.  Therefore, an
     announcement in an Extended Message where the size of the attribute
     set plus the NLRI is larger than 4,096 octets may cause lack of
     reachability.

!    A BGP speaker with a mixture of peers some of which have advertised
!    the BGP Extended Message capability and some which have not, may
!    receive an UPDATE from one of its capable peers that produces an
     ongoing announcement that is larger than 4,096 octets.  When
     propagating that UPDATE onward to a neighbor which has not advertised
!    the BGP Extended Message capability, the sender SHOULD try to reduce
     the outgoing message size by removing attributes eligible under the
     "attribute discard" approach of [RFC7606].  If the message is still
     too big, then it must not be sent to the neighbor ([RFC4271],
     Section 9.2).  Additionally, if the NLRI was previously advertised to
     that peer, it must be withdrawn from service ([RFC4271],
--- 172,187 ----
     speakers which may not support Extended Messages.  Therefore, an
     announcement in an Extended Message where the size of the attribute
     set plus the NLRI is larger than 4,096 octets may cause lack of
     reachability.

!    A BGP speaker that has advertised
!    the BGP Extended Message capability to its peers, may
!    receive an UPDATE from one of its peers that produces an
     ongoing announcement that is larger than 4,096 octets.  When
     propagating that UPDATE onward to a neighbor which has not advertised
!    the BGP Extended Message capability, the speaker SHOULD try to reduce
     the outgoing message size by removing attributes eligible under the
     "attribute discard" approach of [RFC7606].  If the message is still
     too big, then it must not be sent to the neighbor ([RFC4271],
     Section 9.2).  Additionally, if the NLRI was previously advertised to
     that peer, it must be withdrawn from service ([RFC4271],

-----Original Message-----
From: Idr <idr-bounces@ietf.org> on behalf of Randy Bush <randy@psg.com>
Date: Tuesday, July 30, 2019 at 6:23 PM
To: Alvaro Retana <aretana.ietf@gmail.com>
Cc: "idr@ietf.org" <idr@ietf.org>, "\"Mirja Kühlewind via Datatracker\"" <noreply@ietf.org>, "draft-ietf-idr-bgp-extended-messages@ietf.org" <draft-ietf-idr-bgp-extended-messages@ietf.org>, The IESG <iesg@ietf.org>, "idr-chairs@ietf.org" <idr-chairs@ietf.org>
Subject: Re: [Idr]  Mirja Kühlewind's No Objection on draft-ietf-idr-bgp-extended-messages-33: (with COMMENT)

    i have pushed -34, as there have been lots of small changes since -33
    and iesg readers should not have to trip over old fixed junk, and
    instead find new junk.

    randy

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