RE: BGP Route Reflector - Route Server, Router, etc

[James Breeden <James () arenalgroup co>]

Justin,

Fusion has run Route Reflection for some time as we didn't want to play full mesh. 

Our current design is that we have 2 routers that are designated as the route reflectors, and every other router 
maintains RR sessions with those. There is no real additional overhead as the BGP transactions and messaging are 
handled at the management plane of most routers, not the routing plane. Ours are directly on our Brocade MLXe.

As we are scaling past the initial build, we are running into certain minor routing hiccups dealing with remote routers 
sometime preferring routes from the reflectors vs their closer routes. We found this to be a function of ingesting 
transit and default routes directly into route reflector routers and that those routes tended to get preferred in the 
table than routes from other routers in the network. Our answer to this and what we are deploying this year is that we 
are picking a site per time zone to be a Route Reflector, which will give us 4 RRs in the states, but we will not use 
sites that are Transit ingest sites. This way we are more balancing the BGP table across the entire network. Also, I 
believe we will move to default-free status this year with this same move. 

Happy to discuss more indepth offlist if you'd like. 

​-- 

James Breeden
The Fusion Network 
jwb () gotfusion net
fusion 844.548.1421
direct 512.360.0000
cell 512.304.0745
www.gotfusion.net
facebook.com/gotfusion

-----Original Message-----
From: NANOG [mailto:nanog-bounces () nanog org] On Behalf Of Justin Krejci
Sent: Thursday, January 12, 2017 2:33 PM
To: NANOG ‎[nanog () nanog org]‎ <nanog () nanog org>
Subject: BGP Route Reflector - Route Server, Router, etc

Nanog,

I am working on some network designs and am adding some additional routers to a BGP network. I'd like to build a plan 
of changing all of the existing routers over from full iBGP mesh to something more scalable (ie route reflection). 
Fortunately, I am also going to be able to decommission some older routers from the network and so shrinking the 
existing iBGP full mesh is something I am all too happy to spend time and energy on.

For the purpose of this thread though, I am not really interested in the route reflector vs confederation discussion.

In doing some research[1][2][3][4][5] I see a lot of discussions, config examples, etc on using route reflectors but 
most suggest picking a router, or more appropriately a set of routers, to become route reflectors within an ASN. I have 
not found many resources discussing using a non-router box as a route reflector (ie a device not necessarily in the 
forwarding path of the through traffic). I am thinking things like OpenBGPd and BIRD could make a good route reflector 
though they are most often discussed in the context of IXPs (ie eBGP sessions).

I am wondering if people can point me in the direction to some good resource material on how to select a good BGP route 
reflector design. Should I just dust off some 7206VXR routers to act as route reflectors? Use a few existing live 
routers and just add the responsibility of being route reflectors, is there a performance hit? Install and run BIRD on 
new server hardware? Buy some newer purpose built routers (Cisco, Juniper, Brocade, etc) to act as route reflectors and 
add them to the iBGP topology? GNS3 running IOS on server hardware? Something else? How many reflectors should be 
implemented? Two? Four?

What are the pros and cons of one design over another? On list or private off list replies would be great; I'd welcome 
real world experiences (especially any big gotchas or caveats people learned the hard way) as well as just links to 
previous discussions, PDFs, slideshows, etc. Heck even a good book suggestion that covers this topic would be 
appreciated.

[1] - iBGP-to-RR migration slideshow: http://meetings.ripe.net/ripe-42/presentations/ripe42-eof-bgp/sld015.html
[2] - General RR design issues: http://www.netcraftsmen.com/bgp-route-reflector-design-issues/
[3] - Video intro to RR from Cisco: 
http://www.cisco.com/c/dam/en_us/training-events/le31/le46/cln/qlm/CCIP/bgp/introducing-route-reflectors-2/player.html
[4] - Quagga and BIRD as RR example: 
https://bsdrp.net/documentation/examples/bgp_route_reflector_and_confederation_using_quagga_and_bird
[5] - Countless hours on youtube: https://www.youtube.com/results?search_query=bgp+route+reflector

Lots more data is out there of course as that is part of my problem.

Thanks!

Justin