Can someone please assist me with this issue?
I have an internet edge router and do not want to receive the full BGP table from the internet.
What is the best way to go? e.g best practices.
my next hop is my ISP using a /30 ip address
Receiving a default route is suggested if you are an end user. In this way, you do not have to deal with so many routes which consume memory and need administration. ISPs are usually willing to send you a default route as opposed to full internet routes. You might implement filtering as others suggested to prevent adding wrong routes to the routing table in case of misconfiguration. Having another link to another ISP is also recommented in order to avoid single link failure.
Below would a very basic example of an bgp peering to an Isp
With in/outbound filtering.obviously you can amend to this to suit your needs
Ip as-path access-list permit ^$
ip prefix-list default permit 0.0.0.0/0
Router bgp xx
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)
Neigbour x.x.x.x filter-list 10 out ( advertise only local routes)
You can do couple of things in this case:
- You can ask your ISP to not send the whole Internet Routing table but a default route for Internet connectivity.
- if that is not possible, then you can perform route filtering on your router permitting only those prefixes that you need in your network.
Hope this helps
- if that is not possible, then you can perform route filtering on your router denying all prefixes received from the ISP and configure a static default route on your router pointing to your ISP router IP address as the next-hop.