ECS4660-28F_Management Guide-R03

C HAPTER 51 | IP Routing Commands
Border Gateway Protocol (BGPv4)
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ROUTE REFLECTORS
Route reflection designates one or more iBGP speakers as router
concentrators or route reflectors, which are allowed to re-advertise routing
information within the same autonomous system. It also clusters a subset
of iBGP speakers with each route reflector (also known as route reflector
clients), and adds several new attributes to help detect routing loops.
Using the cluster hierarchy, connections are only required between the
route reflector and its clients, overcoming the normal requirement for full-
mesh connectivity among all iBGP speakers.
Figure 556: Connections for Single Route Reflector
Route reflector clients are not aware that they are connected to a route
reflector, and function as though fully meshed within the autonomous
system. For redundancy, a cluster many contain more than one route
reflector. Each cluster is identified a Cluster-ID. When there is only one
route reflector in a cluster, the Cluster-ID is the BGP identifier of the route
reflector. If there is more than one route reflector in a cluster, a common
identifier can be defined for use by all route reflectors in the cluster.
Figure 557: Connections for Multiple Route Reflectors
Router
Router
Router
Router
Route
Reflector
Router
eBGP
Speaker
Router
Advertised
Routes
Reflected
Routes
Router
Router
Router
Router
Route
Reflector
Router
eBGP
Speaker
Router
Cluster
Router
Advertised
Routes
Router
Non-clients
Router
Router
eBGP
Speaker
Advertised
Routes