Cisco Systems OL-14356-01 Network Router User Manual


 
Implementing BGP on Cisco IOS XR Software
Information About Implementing BGP on Cisco IOS XR Software
RC-35
Cisco IOS XR Routing Configuration Guide
OL-14356-01
Figure 6 Three Fully Meshed iBGP Speakers
With route reflectors, all iBGP speakers need not be fully meshed because there is a method to pass
learned routes to neighbors. In this model, an iBGP peer is configured to be a route reflector responsible
for passing iBGP learned routes to a set of iBGP neighbors. In Figure 7, Router B is configured as a route
reflector. When the route reflector receives routes advertised from Router A, it advertises them to
Router C, and vice versa. This scheme eliminates the need for the iBGP session between routers A
and C.
Figure 7 Simple BGP Model with a Route Reflector
S4217
External
BGP
speaker
Routes
advertised
Fully meshed
autonomous
system
Routes
Routes
Routes not
advertised
Router A Router A
Router B
Router C
S4219
External
BGP
speaker
Partially meshed autonomous system
Route
reflector
Reflected
routes
Routes
Routes
Router A
Router B
Router A Router C