[j-nsp] BGP Prefix-Limit On A Session

[Pedro Roque Marques]

dr at cluenet.de (Daniel Roesen) writes:

> On Thu, Feb 26, 2004 at 08:58:59AM -0800, Pedro Roque Marques wrote:
> > btw: 6.3 tries to be smarter than previous releases in this regard. If
> > you do change the export parameters of the first neighbor in the
> > group, that neighbor will get reset now,
> 
> WHY a reset? NOTHING regarding session parameters changed when the
> export chain is modified!
> 

I'm not sure that you really want to have an answer as to the question
"why a reset"... but i'll assume you'd like to understand the rational
behind it.

All peers in a group share rib-out entries. When you split a group by
modifying export policies rib-out entries are no longer applicable to
both groups... the new group needs to create new rib-out entries, and
the old ones are no longer valid.

The complexity of implementing this results in a rather non trivial
exercise.

In terms of the overall reliability of the application, you most
likely get a better result out of predictable session resets than
unpredictable rpd crashes as result of the added complexity.

While from a provider point of view, i understand that you may wish to
have the system handle configuration changes w/ minimum disruption
possible, there is a cost to it.

JunOS(*) current choice is torwards one set of tradeoffs. You are
welcome to agree or disagree w/ it, but it is a rational choice that
is made. As with all engineering choices it has advantages and
drawbacks.

regards,
  Pedro.

(*) Not that anyone needs to be reminded, but... i don't speak for
Juniper, much less in this mailing list. This just represents my
current understanding, which may be flawed.