Dell PowerConnect B-FCXs Configuration Manual page 1061

FIGURE 147
AS 1
Support for RFC 2796
Route reflection on Dell PowerConnect devices is based on RFC 2796. This updated RFC helps
eliminate routing loops that are possible in some implementations of the older specification, RFC
1966.
NOTE
The configuration procedure for route reflection is the same regardless of whether your software
release is using RFC 1966 or RFC 2796. However, the operation of the feature is different as
explained below.
RFC 2796 provides more details than RFC 1966 regarding the use of the route reflection attributes,
ORIGINATOR_ID and CLUSTER_LIST, to help prevent loops:
•
•
The Dell PowerConnect device handles the attributes as follows:
•
PowerConnect B-Series FCX Configuration Guide
53-1002266-01
Example of a route reflector configuration
Cluster 1
Route
Reflector 1
Route
Reflector
Client 1
10.0.1.0
ORIGINATOR_ID – Specifies the router ID of the BGP4 switch that originated the route. The
route reflector inserts this attribute when reflecting a route to an IBGP neighbor. If a BGP4
switch receives an advertisement that contains its own router ID as the ORIGINATOR_ID, the
switch discards the advertisement and does not forward it.
CLUSTER_LIST – A list of the route reflection clusters through which the advertisement has
passed. A cluster contains a route reflector and its clients. When a route reflector reflects a
route, the route reflector adds its cluster ID to the front of the CLUSTER_LIST. If a route reflector
receives a route that has its own cluster ID, the switch discards the advertisement and does
not forward it.
The Layer 3 Switch adds the attributes only if it is a route reflector, and only when advertising
IBGP route information to other IBGP neighbors. The attributes are not used when
communicating with EBGP neighbors.
EBGP
Route
Reflector 2
Route
Reflector
Client 2
10.0.2.0
Optional configuration tasks
AS 2
Switch
IBGP
Switch
IBGP
30
IBGP
Switch
1019