Enterasys Networks X-Pedition XSR CLI - Manual (Page 312)

BGP Set Commands
6-116 Configuring the Border Gateway Protocol
Syntax of the “no” Form
The no form of this command removes the set community value:
no set community
Mode
Route‐map configuration: XSR(config-route-map)#
Example
The following example configures the set community value in the context of configuring route map
1 and the neighbor send community value:
XSR(config)#ip access-list 37 permit 10.0.0.0 255.0.0.0
XSR(config)#route-map 1 permit 1
XSR(config-route-map)#match ip address 37
XSR(config-route-map)#set community 500:10
XSR(config-route-map)#exit
XSR(config)#route-map 1 permit 2
XSR(config-route-map)#set community none
XSR(config-route-map)#exit
XSR(config)#router bgp 100
XSR(config-router)#neighbor 192.168.1.1 remote-as 101
XSR(config-router)#neighbor 192.168.1.1 send-community
XSR(config-router)#neighbor 192.168.1.1 route-map 1 out
Route map 1 is applied to the outgoing BGP updates between this router and its peering neighbor
identified by IP address 192.168.1.1 in AS 101. The first instance of route map 1 matches the
destinations in the BGP updates against the criteria specified in ACL 37 (10.0.0.0/8). If there is not a
match, the second instance of route map 1 is invoked, which matches on all remaining routes and
removes any community attributes. This means that routes matching ACL 37 criteria will have a
community attribute set to 500:10, but all of the other routes advertised to 192.168.1.1 will not.
The BGP peer 192.168.1.1 will then have the option to apply a desired routing policy to all routes
arriving from this router with the community attribute set to 500:10.
set dampening
This command configures route flap dampening, a mechanism to combat network overhead
which arises from the proliferation of uncontrolled disconnecting/reconnecting networks.
With route dampening, you can address these problem routes as follows:
local-AS Established community which specifies that routes containing this value
should not be advertised to external BGP peers.
no-advertise Established community which specifies that routes containing this value
should not be advertised to any other BGP peers (internal or external).
no-export Established community which specifies that routes containing this value
should not be advertised outside a BGP confederation boundary.
none Removes any existing communities.