Chapter 10. BGP in Larger Networks

This chapter deals with issues that are relevant for large networks. In larger networks, memory and especially CPU constraints become more important, because the difference in CPU speed between different routers in the network typically grows larger. In larger networks, internal BGP scalability quickly becomes an issue, and the interaction between interior routing protocols and BGP gets more complex.

Peer Groups

Some routers have a long list of BGP neighbors. It’s then common to have several settings that are the same for each neighbor. In these cases, it’s more efficient to create a peer group, assign the settings to the group, and have the neighbors share settings by making them members of the group. Example 10-1 shows two peer groups and several members.

Example 10-1. BGP peer groups
! router bgp 60055 network timers bgp 5 15 neighbor ebgp peer-group neighbor ebgp prefix-list infilter in neighbor ebgp prefix-list outfilter out neighbor ebgp maximum-prefix 100 neighbor ebgp filter-list 2 out neighbor ibgp peer-group neighbor ibgp remote-as 60055 neighbor peer-group ibgp neighbor peer-group ibgp neighbor peer-group ibgp neighbor remote-as 1000 neighbor peer-group ebgp neighbor description Net1000 neighbor password abc def ghi neighbor remote-as 2000 neighbor peer-group ebgp neighbor description 2000net ...

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