Configuring Bgp Route Reflector - Huawei Quidway S3500 Series Operation Manual

Operation Manual - Routing Protocol
Quidway S3500 Series Ethernet Switches

5.2.15 Configuring BGP Route Reflector

To ensure the interconnection between IBGP peers, it is necessary to establish fully
connected network. In some networks, there are large numbers of IBGP peers, and the
internal BGP network becomes very large, consequently the costs to establish fully
meshed network are very large. Thus, it is required to utilize new peer technology. The
basic idea of route reflector conception is to specify a centralized router as the focus of
the internal session. Multiple BGP routers can peer one central point, and then multiple
route reflectors will peer again.
Route reflector is the centralized point of other routers, and other routers are called the
clients. The client is the peer of the route reflector and switching the routing information
with it. The route reflector will reflect the information in order among the clients.
In the following figure, Router A receives an update packet from the external peer and
transmits it to Router C. Router C is a route reflector with two peer clients: Router A and
Router B.
Router C reflects the update packet from client Router A to client Router B. Under such
configuration, the peer session between Router A and Router B is actually eliminated
because the route reflector will transfer the BGP information to Router B.
EBGP EBGP
Figure 5-1 The route reflector diagram
The reflector is the router that can complete the route reflection function. The route
reflector regards the IBGP peers as client and non-client. All peers that do not belong to
such cluster in the autonomous system are the non-clients. The designation of route
reflector and the addition of the client peer are implemented with the command peer
reflect-client.
The client peer shall not establish peer-relationship with IBGP outside the relevant
cluster. The non-client peer and the route reflector, as well as one non-client peer and
the other non-client peer, forms a fully meshed network because they follow the basic
principles of IBGP fully meshed network. The route reflection function is only completed
Router C Router C
Route reflector Route reflector
Router Router
Route updated Route updated
Router A Router A
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5-19
Chapter 5 BGP Configuration
Route reflected Route reflected
EBGP EBGP
Router B Router B