BGP Peer Limitation

[kcchief01]

I have been trying to find any reference that states if there is a limitation or a design recommendation on how many bgp peers a single router should have. I know that for OSPF the recommendation is 50-60 neighbors, and for EIGRP it is around 40. Is there such a "rule" or best practice when designing a large BGP network.

Thank!

Eric

[allissrcco]

I have not seen any documents which place limitations on the number of peers, the only ones I have seen quote recommended memory sizes dependng on the number of networks.

Check this out it might help http://www.ietf.org/rfc/rfc1774.txt

Richard.

[saridder]

I haven't seen anything specifically, but the Cisco Press Book CCIE Network Design and Case Studies recommends 30 neighbors if running a distance-vector protocol, which BGP kind of is. I'm sure you can do more with a lot of RAM, so I guess it depends on the router's capabilities. All the rules are flexible, as I've seen EIGRP networks running on a 6509 with 500 neighbors.

[Gilles Dufour]

the problem with numbers is that you have to be really carefull about the context.

You numbers for OSPF are wrong. These are numbers from 5 years ago. Unfortunately, all books on the subject still propagate this information while it is not true anymore.

I have seen live network with 200 routers in 1 area.

Regarding BGP, it also depends on the type of router (CPU, memory, ..), it also depends on the type of config (peer group or not, soft reconfiguration or not).

In peer group I would say a 100 routers is ok.

[tmoreo]

I don't know of any specific BGP data however I agree with gdufour's response. Most numbers are given from 2500 series routers. Consider what equipment you are going to use and read the OSPF design guide.

http://www.cisco.com/warp/public/104/1.html

Part two section on memory issues can help with the memory part. I have not found anything on the CPU usage of the algorithm. You can "guestimate" that since CPU speed doubles every 18 months you should be able to double your neighbors (2600 series). I would first look at the equipment you are going to use or you are using then move on from there. Use the weakest (slowest/least memory) equipment as your guide. No use in one piece melting down and rebooting because of overload.