BGP deployment and peering questions

Fri Feb 16 04:30:50 UTC 2001

On Tue, Feb 13, 2001 at 01:00:00PM -0800, Pyda Srisuresh wrote:

  Hi,

  I have a couple of questions concerning BGP deployment. I would
  appreciate any feedback from folks knowledged in the deployment. 
  Thanks very much. 

warning
do not consider myself knowledged in bgp deployment.
however, caida's skitter project 
http://www.caida.org/tools/measurement/skitter
has more data on topology/connectivity (by far)
than anything i've encountered 

and some of our analyses may not
be totally useless to you
(andre did all the work below;
i just translated it to english...)

  Pyda:
  1. What is the maximum no. of peers a core-BGP peers with externally?
     What is a good average or median number? How does this vary with
     Tier-1 BGP speakers vs. Tier-2 BGP speakers? Also, What is an 
     average no. of peers a BGP border router multi-homes with? (Do not
     include Border routers with a single ISP peer - only the multi-homed
     border routers)

see:
http://www.caida.org/~broido/bgp/asoutdeg.html

  2. I understand, an AS by itself does not originate more than 
     10,000 (UUnet being the one with this many) subnets. But, 
     I believe, when you peer with a tier-1 ISP BGP speaker, you 
     will get AS Paths for the entire 90,000+ routes (or whatever 
     the maximum core routing tabel size is) exchanged at BGP
     connection setup time. On the other hand, I believe, the number
     of routes exchanged to be much less when you peer with a tier-2 BGP. 
     What is a resonable average size of routing entries you could 
     expect from a tier-2 ISP (and even a Tier-1 ISP, for that matter)?

http://www.caida.org/~broido/bgp/stubas.html

(viz could be better on some of the graphs,
but you'll get the point)

btw wrt your UUcomment 
i think 701 originates about 2300 prefixes
(at least on 29 november seen from routeviews,
w another 74 announced by 701 and by other ASes...  to routeviews, anyway)
(if you count 702-705,7046,284,etc, it was another few K maybe.  
not more than 5K total even including uucanada.)
another 1K or so might be announced by 701 
from stubs behind 701etc, haven't done that analysis

  3. Do you have an estimate of memory requirements for some of the core
     routers (peering with tier-1 ISPs or tier-2 ISPs)? Is there a 
     relation with the number of BGP peers?

think someone else got that one
(good thing)

k and andre

//
	to the pure geometer the radius of curvature is
	an incidental characteristic - 
	like the grin of the cheshire cat.  
	to the physicist it is an indispensable characteristic.  
	it would be going too far to say that to the physicist i
	the cat is merely incidental to the grin.  
	physics is concerned with interrelatedness such 
	as the interrelatedness of cats and grins.  
	in this case the cat without a grin and the grin
	without a cat are equally set aside as purely
	mathematical phantasies.  
	  -- sir arthur eddington, the expanding universe
//