[j-nsp] bgp config changes (was: autonomous-system N loops L)

[Daniel Roesen]

On Thu, Dec 11, 2003 at 11:18:15PM -0800, Pedro Roque Marques wrote:
> As far as sessions resets are concerned, you can always expect a reset
> if you change a parameter that is negotiated on session
> establishement.

Correct, but JunOS resets sessions even if nothing of that kind
is changed.

Even simply changing the export chain of the first neighbor of
the group resets all other sessions. There is absolutely no technical
reason, nor "has its advantages". Actually, I'd flatly call it a
serious bug. So far, JTAC disagreed. See 2003-0121-068 for
a discussion on why we think that enabling/disabling global
"remove-private" must not reset all BGP sessions of a router.
ER6574 was opened to fix this, and PR31609 to better document the
current behavior. PR31609 was closed with no committed-in release
date, but current (JunOS 6.1) documentation still has no warning.

> However if you deactivate the peer first and then modify its export
> policy this will not happen. I hope you can use that as a workaround
> while we don't get around to do something smarter in the code.

Changing anything that does not affect BGP _session_ parameters
_MUST_NOT_ reset a session. Anything else is a bug and introduces
artificial downtime for customers which is technically not necessary.

> We have also been asked by several customers to document the current
> behaviour bettter...

See PR31609... :-)


Best regards,
Daniel