Best practice for BGP session/ full routes for customer

Mark Tinka mark.tinka at seacom.mu
Tue Jul 8 20:56:26 UTC 2014


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.
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