Updating export filter for OSPF

[Ruben Laban]

On Tuesday 25 October 2011 at 10:13 (CET), Ondrej Zajicek wrote:
> On Mon, Oct 24, 2011 at 04:38:32PM +0200, Ruben Laban wrote:
> > On Monday 24 October 2011 at 16:18 (CET), Ondrej Zajicek wrote:
> > > Real 'sledgehammer' is restart command. Configure command tries to be
> > > gentle, but restart the protocol if necessary (like if BGP import
> > > filter is changed and the neighbor does not support route refresh).
> > 
> > Ok, clear. But aren't route refreshes a fundamental part of BGP? Or am I
> > missing/misunderstanding something here?
> 
> No, they are an extension (RFC 2918), but widely implemented.

Ah, I see. Never really looked deeply into the inner workings of BGP. And a 
"normal" user shouldn't have to I'd say. Yet, learn something new (or even 
more) every day ;-)

> > What I don't understand though, when I was just altering null-routes and
> > export filters, a configure did result in a hard clear according to my
> > peer. Are there any other scenarios where configure could lead to a hard
> > clear and not a soft clear? One thing that comes to mind is that I
> > enabled 'next hop self' as well, though I don't see why that'd warrant a
> > hard clear either?
> 
> Proper reconfiguration of BGP sessions is not implemented in BIRD, so
> changing other parameters (than import/export) of BGP (like 'next hop
> self') will lead to session restart.

Good to know.

On Tuesday 25 October 2011 at 10:22 (CET), Ondrej Zajicek wrote:
> On Mon, Oct 24, 2011 at 03:15:14PM +0200, Ruben Laban wrote:
> > Speaking of which, lines like these:
> > 
> >   Routes:         374804 imported, 3 exported, 374801 preferred
> > 
> >
> > are a bit "misleading". As my peer claims to only 2 routes being
> > advertized by  me. Being able to "refresh" those advertizements without
> > completely restarting the respective BGP session would be nice.
> 
> Yes, export counter is unreliable under some circumstances (esp. when
> 'configure soft' is used). You can 'refresh' advertisements using 'reload'
> command.

Again, good to know. I guess it's getting about time I'd create a "cheatsheet" 
for my co-workers so they won't be "misled" easily by stuff like this.

Thanks for all the info/pointers/etc!

Regards,
Ruben Laban