Need for Route reflectors

Posted: February 12, 2016 in BGP

Simple reason is AS number is used for loop avoidance.

When routes are exchanged between the routers which belongs to the same As , AS_PATH list is not modified (routing update within AS).
So this situation can create routing loop and to avoid this there is BGP split horizon rule


Due to split horizon rule we need to create full mesh of IBGP sessions between the routers within same AS to avoid routing black hole. This full mesh condition is really bad consider example if there is a stub router with single neighbor with single uplink
(If there are N router in the As then we need to create (N*(N-1))/2 sessions)

To avoid such large number of BGP session and conserve useful resources we are using Route reflectors which bypasses Split horizon rule

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s