Re: [Idr] WG adoption call for draft-abraitis-bgp-version-capability-08, to end September 25

[Robert Raszuk <[e-mail]>]

I am afraid you are talking about BGP version while Linda is asking about
the subject draft bgp version ... Both are completely unrelated "versions".

While we are here I did reread RFC4271 and I am not sure either if there is
text to mandate closing the session when new BGP OPEN Optional Parameter is
not recognized. Neither does FSM. Generating NOTIFICATION and continue
should be allowed by the spec unless I missed some embedded mandate to
close it.

Thx,
R.

On Mon, Jan 16, 2023 at 8:21 PM Jeffrey Haas <[e-mail]> wrote:

> Linda,
>
> On Mon, Jan 16, 2023 at 06:54:29PM +0000, Linda Dunbar wrote:
> > RFC4271 states that if the version number is not supported, an error
> message should be sent. But RFC4271 didn't say if the BGP Open session
> should be failed.
> > I am just curious if BGP session can be started even if the  version
> number is not supported?
>
> RFC 4271, §6.2:
> : 6.2.  OPEN Message Error Handling
> :
> :    All errors detected while processing the OPEN message MUST be
> :    indicated by sending the NOTIFICATION message with the Error Code
> :    OPEN Message Error.  The Error Subcode elaborates on the specific
> :    nature of the error.
> :
> :    If the version number in the Version field of the received OPEN
> :    message is not supported, then the Error Subcode MUST be set to
> :    Unsupported Version Number.  The Data field is a 2-octet unsigned
> :    integer, which indicates the largest, locally-supported version
> :    number less than the version the remote BGP peer bid (as indicated in
> :    the received OPEN message), or if the smallest, locally-supported
> :    version number is greater than the version the remote BGP peer bid,
> :    then the smallest, locally-supported version number.
>
> Tersely, if you don't support the right version number, you hang up the
> session with a NOTIFICATION and leave enough of a breadcrumb that the next
> OPEN could arrive at a possibly mutually supported version.
>
> -- Jeff
>