BGP Peering with ISP – Key Considerations

bgpisppeeringprefix

In you case you want to get rid of the static default route and you want to peer with your single ISP, do you need to announce any routes for your side ? I have the below config, is it enough for peering with your ISP ? 

ip prefix-list default permit 0.0.0.0/0

Router bgp xx

no auto-summary

no synchroniszation

Neighbor x.x.x.x remote-as ISP (peer to ISP)

Neighbor x.x.x.x password xxxx ( basic authentication)

Neighbour x.x.x.x prefix-list default in ( accept default only)

Best Answer

There are generally two reasons to use BGP with your ISP:

  1. You have more than one connection to your ISP(s), and you want to influence which path your traffic takes.
  2. You have your own provider independent, registered block of IP addresses, which needs to be advertised.

For most organizations with a single connection to the Internet, there is no reason or advantage to run BGP with your provider. Since there is only one path to the Internet, a static default route is all you need. The ISP already announces their address blocks (of which you use a small part) to the Internet.

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