BGP peering strategies for smaller routers

Tony Wicks tony at
Mon May 2 21:03:18 UTC 2016

I have used variations Gustav's solution below to good effect as well, this also works with two smaller routers providing basic fail over and load balancing. I found its best to take Full + default from one provider and just default from the other. Set a higher local-pref on the default only provider than the full+default one, then filter the full+default routes by AS-path as desired. Incoming control via the normal prepending of outgoing advertisements.

-----Original Message-----
From: NANOG [mailto:nanog-bounces at] On Behalf Of Gustav Ulander
Sent: Tuesday, 3 May 2016 8:30 AM
To: Mike <mike-nanog at>; NANOG list <nanog at>
Subject: RE: BGP peering strategies for smaller routers


When we was in a similar situation we opted for one transit provider to provide a default to us then we filtered on AS-HOPS so prefixes that was more than 3 hops away was denied. 
This way we got the ones that where closest to us and that where more likely to matter. Prefixes that’s more than 3 hops away on both links could probably just as well go on a default insteed. 
However it’s a rather crude way of fixing the issue. We just did it to have the router up while we got extra memory from it. (we had memory shortage after an update that we needed to apply to correct some bug I think. We couldn’t just rollback the update if my memory serves me correct.) 


-----Original Message-----
From: NANOG [mailto:nanog-bounces at] On Behalf Of Mike
Sent: den 2 maj 2016 21:07
To: NANOG list <nanog at>
Subject: BGP peering strategies for smaller routers


     I have an ASR1000 router with 4gb of ram. The specs say I can get
'1 million routes' on it, but as far as I have been advised, a full table of internet routes numbers more than 530k by itself, so taking 2 full tables seems to be out of the question (?).

      I am looking to connect to a second ip transit provider and I'm looking for any advice or strategies that would allow me to take advantage and make good forwarding decisions while not breaking the bank on bgp memory consumption. I simply don't understand how this would likely play out and what memory consumption mitigation steps may be necessary here. Im open to ideas... a pair of route reflectors? 
selective bgp download? static route filter maps?

Thank you.


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