BGP feeds

[pcromwell]

we are setting up a new data center and we have 2 ISP feeds (router A and router B) using BGP coming into 2 of our cisco routers. (router C and router D) We will have a full mesh design so that each Cisco router will both have links to router A and B. Routers C and D will also be connected together via a 3rd interface.
We don't need to download any Internet routing tables, just the default routes really. Say our public IP range is 99.99.99.0/24
would I need to divide the Public subnet into 4 different subnets for example?

99.99.99.0/30 = Router A 99.99.99.1 -> Router C 99.99.99.2
99.99.99.4/30 = Router B 99.99.99.5 -> Router D 99.99.99.6
99.99.99.8/30 = Router C 99.99.99.9 -> Router D 99.99.99.10

then assign the last subnet for all the hosts

There are not many subnets on the data center so I will just add static routes. How does it work if any of the links were to go down, would BGP take care of that process?

[Reza Sharifi · Accepted solution]

For your routers (C and D) to peer with ISPs (A and B) you don't need to break your public IP (99.99.99.0/24).  For each peering, the ISP with provide you a separate /30 to use.  This way you can use your public IP for your internal networks.  Say, you have an internal network and a DMZ, you can break your /24 to 2 /25s and use one for internal and one for DMZ.

HTH

[pcromwell]

many thanks for the reply

that sounds good. In terms of the BGP config on the cisco routers, is the following config all I need to add to be connected onto the Internet?

Router BGP (My AS Number)
neighbor (ISP 1 IP Address) remote-as X
bgp log-neighbor-changes
neighbor (ISP 2 IP Address remote-as XX

network 99.99.99.0 mask 255.255.255.0

[cofee]

Looks fine. If you are adding authentication then you will need to enter command for authentication.

[pcromwell]

thanks for the replies, I now have a clearer understanding.

many thanks again

[Reza Sharifi]

In addition to the config, have look at this link for examples:

The design assumes load sharing but you can always configure them as active/standby

http://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13762-40.html#anc27

HTH