Chapter 50
| 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 2: 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 3: 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
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