BGP Full Route Memory Requirements

[jsabroff]

To process and use full Internet BGP routes effectively, how much memory does a 2651XM router need? Max DRAM for the 2651XM is 256MB, is that enough to work effectively?

[network.king]

Hi

If you are going to have a single Bgp session and going to receive only 1,80,000+ routes , then 256 memory is fine.

But if you plan for receiving from multiple ISP's the whole internet routing table , then the memory is not enough

regards

vanesh k

[minumathur]

Hi

Currently there are 200000 routes available, so if you import all the route then memory requirement is very much high.

suggestion : you go to cisco.com, take higher end series router and check the spefication of that router, this will help you out.

-Minu

[mark.edwards]

I've just checked at UUNET looking glass server. They have in excess of 200k BGP routes which is taking 23mb of memory (see below). Other looking glass servers are showing similar memory consumption.

BGP router identifier 87.249.32.46, local AS number 31323

BGP table version is 36719635, main routing table version 36719635

203274 network entries using 23376510 bytes of memory

407376 path entries using 19554048 bytes of memory

1 multipath network entries and 4 multipath paths

149764/38756 BGP path/bestpath attribute entries using 14976400 bytes of memory

98921 BGP AS-PATH entries using 3080902 bytes of memory

126 BGP community entries using 3424 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 60991284 total bytes of memory

Dampening enabled. 212 history paths, 48 dampened paths

BGP activity 947646/744372 prefixes, 16980350/16572974 paths, scan interval 60 secs

[Danilo Dy]

Try not using a router with 256MB maximum, since this is the minimum requirement for full internet BGP. This is if you have your own prefix and ASN and multihoming.

However, if you don't have your own prefix and ASN (and you have that 2651XM router in yourt hand) and your ISP is providing you IP Address and Private ASN - your ISP can announce partial BGP route to you which is a 128MB is required, but of course you should get 256MB instead.

[jsabroff]

This installation has two Internet routers and two ISPs (one to each router). The two routers also use iBGP, which I believe would mean that each router would hold a separate table, one for each ISP. If this is the case, are you saying that 256MB memory is not enough for each router in this installation?