Re: Best practice for BGP session/ full routes for customer

[Nick Hilliard <nick () foobar org>]

On 14/07/2014 18:32, Jeff Tantsura wrote:
> BGP to RIB filtering (in any vendor implementation) is targeting RR which
> is not in the forwarding path, so there¹s no forwarding towards any
> destination filtered out from RIB.
> Using it selectively on a forwarding node is error prone and in case of
> incorrect configuration would result in blackholing.

there are other drawbacks too: the difference in convergence time between <
24k prefixes  and a full dfz is usually going to be large although I
haven't tested this on an me3600x yet.  Also these boxes only have 1G of
memory might be a bit tight as the dfz increases.  For sure, it's already
not enough on a bunch of other vanilla ios platforms.

Nick

> Cheers,
> Jeff
>
>
>
>
> -----Original Message-----
> From: Mark Tinka <mark.tinka () seacom mu>
> Organization: SEACOM
> Reply-To: <mark.tinka () seacom mu>
> Date: Tuesday, July 8, 2014 at 1:56 PM
> To: "nanog () nanog org" <nanog () nanog org>
> Subject: Re: Best practice for BGP session/ full routes for customer
>
> > On Monday, July 07, 2014 08:33:12 PM Anurag Bhatia wrote:
> >
> > > In this scenario what is best practice for giving full
> > > table to downstream?
> >
> > In our case, we have three types of edge routers; Juniper
> > MX480 + Cisco ASR1006, and the Cisco ME3600X.
> >
> > For the MX480 and ASR1006 have no problems supporting a full
> > table. So customers peer natively.
> >
> > The ME3600X is a small switch, that supports only up to
> > 24,000 IPv4 and 5,000 IPv6 FIB entries. However, Cisco have
> > a feature called BGP Selective Download:
> >
> >      http://tinyurl.com/nodnmct
> >
> > Using BGP-SD, we can send a full BGP table from our route
> > reflectors to our ME3600X switches, without worrying about
> > them entering the FIB, i.e., they are held only in memory.
> > The beauty - you can advertise these routes to customers
> > natively, without clunky eBGP Multi-Hop sessions running
> > rampant.
> >
> > Of course, with BGP-SD, you still need a 0/0 + ::/0 route in
> > the FIB for traffic to flow from your customers upstream,
> > but that is fine as it's only two entries :-).
> >
> > If your system supports a BGP-SD-type implementation, I'd
> > recommend it, provided you have sufficient control plane
> > memory.
> >
> > Cheers,
> >
> > Mark.