User guide

E
XTREME
W
ARE
S
OFTWARE
U
SER
G
UIDE
13-3
BGP C
OMMUNITIES
• Community – Identifies a group of destinations that share one or more common
attributes.
• Cluster_ID – Specifies a 4 byte field used by a route reflector to recognize updates
from other route reflectors in the same cluster.
BGP C
OMMUNITIES
A BGP community is a group of BGP destinations that require common handling.
ExtremeWare supports the following well-known BGP community attributes:
• no-export
• no-advertise
• internet
BGP F
EATURES
This section describes the following BGP features supported by ExtremeWare:
• Route Reflectors
• Route Confederations
• Route Aggregation
• IGP Synchronization
• Using the Loopback Interface
• OSPF to BGP Redistribution
R
OUTE
R
EFLECTORS
Another way to overcome the difficulties of creating a fully-meshed AS is to use route
reflectors. Route reflectors allow a single router to serve as a central routing point for the
AS or sub-AS.
A cluster is formed by the route reflector and its client routers. Peer routers that are not
part of the cluster must be fully meshed according to the rules of BGP.
A BGP cluster, including the route reflector and its clients, is shown in Figure 13-1.