[58512] in North American Network Operators' Group
Re: Communities BCP [was: RE: BGP Path Filtering]
daemon@ATHENA.MIT.EDU (Guy Tal)
Fri May 16 18:29:19 2003
Date: Fri, 16 May 2003 17:28:37 -0500 (EST)
From: Guy Tal <guy@gblx.net>
To: "Stephen J. Wilcox" <steve@telecomplete.co.uk>
Cc: nanog@merit.edu
In-Reply-To: <Pine.LNX.4.44.0305162258110.15940-100000@MrServer>
Errors-To: owner-nanog-outgoing@merit.edu
comments inline...
On Fri, 16 May 2003, Stephen J. Wilcox wrote:
>
> On Fri, 16 May 2003, Danny McPherson wrote:
>
> > On 5/16/03 1:26 PM, "Jay Ford" <jay-ford@uiowa.edu> wrote:
> >
> > > You can & definitely should strip those community values on announcements you
> > > receive from EBGP peers. Interesting things happen if you let others turn
> > > your routing policy knobs when you think they can't reach them.\
> >
> > Agreed.
> >
> > Likewise, when you receive communities (and MEDs, ugh!) [if possible] you
> > should reset them (v. employing 'additive'). Unnecessary propagation and/or
>
> Hmm.. assuming you're interconnecting at multiple points with the same ASN they
> will probably want to indicate to you where to send traffic to them using MEDs,
> if you go stripping them out you lose that info, check the peering policy.. this
> may put you in breach.
>
> Even without a breach of policy the MED will help find the best path to a route
> thats identical at two points and if you take it out you lose that.
All a matter of perspective. I would assume most people want to use
closest exit on their networks. Imagine how nice it would be if you could
hand off traffic to a peer that is your closest exit, then force them to
carry the traffic back to you at that same point from across the country
or across the globe!
> Altho I'd agree if you'd say to clear the communities and MEDs on egress, thats
> an okay thing to do.
Spank me if I'm wrong here, but you don't pass MEDs on transitively
anyway. And if you strip communities off, you limit your
peers/customers/providers from being able to use the same control that you
are asking for.
Guy Tal
