In the case of ibgp full mesh of bgp connections are required, this increases the number of TCP connections required on a bgp speaker.
We can use route reflectors to reduce this behaviour, there is no need of full mesh between the bgp speakers.
Another method which can be used to reduce the number of bgp connections is using the confederations.
RR and its clients forms a cluster clients have a ibgp session with the RR only there is no ibgp session between the clients.
If RR receives a route from the client it first determines if it is a best path if the route is best, advertise the route to other clients except the one from which it has reeived the route.
Also the RR propogates the route to the non client peers, the non client peers propogate the route to other ebgp speakers.
In RR split horizon rule is violated loops might be possible this is taken care of by the optional non transitive attributes originator id and cluster list these are only available in an RR envirinment.
Originator ID :- This is set by the router that originated the route this remains unmodified in the AS any router that received the route should check the originator id if that matches with the router id that route is ignored.
Cluster list:- This is used by the RR only, this contains the cluster id if the cluster id is found on the route received then the route is ignored.
We can use route reflectors to reduce this behaviour, there is no need of full mesh between the bgp speakers.
Another method which can be used to reduce the number of bgp connections is using the confederations.
RR and its clients forms a cluster clients have a ibgp session with the RR only there is no ibgp session between the clients.
Non client should be fully meshed with the RR
Also the RR propogates the route to the non client peers, the non client peers propogate the route to other ebgp speakers.
In RR split horizon rule is violated loops might be possible this is taken care of by the optional non transitive attributes originator id and cluster list these are only available in an RR envirinment.
Originator ID :- This is set by the router that originated the route this remains unmodified in the AS any router that received the route should check the originator id if that matches with the router id that route is ignored.
Cluster list:- This is used by the RR only, this contains the cluster id if the cluster id is found on the route received then the route is ignored.
