Subject: BGP4 draft ; section 6.2

From: [email-masked]
Date: Fri, 13 Sep 2002 15:43:55 +0200

All,

I have a doubt related to section 6.2: OPEN message error handling,
related to the statement:

" If one of the optional parameters in the Open mesage is not recognized,
then the error subcode is set to 'unsupported optional parameters"

We have hit on this line when we were testing a BGP connection between
a speaker that supported capability negotiation and a speaker that did
not.

The speaker that did not support the neogotiation closed down the peering
session using the error clause mentioned above.  Sometimes this lead
to the other router to repeat the OPEN message with the Capability optional
parameter; a game that went on for minutes.

This router manufacturer stated in a reply to this that :

"One should not close down the connection if an optional parameter
is unrecognised. That would make this parameter basically mandatory.

This is an well known error in the BGP spec. Neither Cisco or Juniper
do this"

If this is true it might be good to adapt the text.

Hans de Vleeschouwer

Alcatel.

---

From: Mathew Richardson <[email-masked]>
Date: Fri, 13 Sep 2002 10:07:43 -0400

> [email-masked] <[email-masked]> [Fri, Sep 13, 2002 at 03:43:55PM +0200]:

From rfc2842:

   A BGP speaker determines that its peer doesn't support capabilities
   advertisement, if in response to an OPEN message that carries the
   Capabilities Optional Parameter, the speaker receives a NOTIFICATION
   message with the Error Subcode set to Unsupported Optional Parameter.
   In this case the speaker should attempt to re-establish a BGP
   connection with the peer without sending to the peer the Capabilities
   Optional Parameter.

mrr