D-Link DI-1750 Reference Manual page 260

6.12.17 Configure BGP Community Properity
BGP supports transit policies via controlled distribution of routing information. The distribution of routing
information is based on one of the following three values:
IP address (see the "Configure BGP Route Filtering by Neighbor" section earlier in this chapter).
The value of the AS_PATH attribute (see the "Configure BGP Path Filtering by Neighbor" section earlier
in this chapter).
The value of the COMMUNITIES attribute (as described in this section).
The COMMUNITIES attribute is a way to group destinations into communities and apply routing
decisions based on the communities. This method simplifies a BGP speaker's configuration that
controls distribution of routing information.
A community is a group of destinations that share some common attribute. Each destination can belong
to multiple communities. Autonomous system administrators can define to which communities a
destination belongs.
The COMMUNITIES attribute is an optional, transitive, global attribute in the numerical range from 1 to
4,294,967,200. Along with Internet community, there are a few predefined, well-known communities, as
follows:
♦ no-export--- Do not advertise this route to EBGP peers(included EBGP peers of internal
autonomous system).
♦ no-advertise--- Do not advertise this route to any peer.
♦ local-as--- Do not advertise this route to peers outside the autonomous system (can be advertised
to other sub-autonomous systems).
A BGP speaker can set, append, or modify the community of a route when you generate, receive or
retransmit routes. When routes are aggregated, the resulting aggregate has a COMMUNITIES attribute
that contains all communities from all the initial routes.
By default, no COMMUNITIES attribute is sent to a neighbor. You can specify that the COMMUNITIES
attribute be sent to the neighbor by using the following command in router configuration mode:
neighbor
send-community
In the prompt Select 12 option
(00)A.B.C.D
Please Input the code of command to be excute(0-0): 0
input 0，Select A.B.C.D option ，then prompt 为：
Please input a IP Address:
input IP ，prompt is as below:
(00)default-originate
......
(12)send-community
......
Please Input the code of command to be excute(0-17): 12
input 12，Select send-community option .
To configure the community attribute for route, perform the following tasks:
route-map map-name sequence-number {deny |
permit}
set community community-value
router bgp autonomous-system
Command
{ip-address |
peer-group-name}
，prompt is as below:
IP address of neighbor
Permit announcement of default route to neighbor
Allow send community attibute to neighbor
Command
Model Name
Specify that the COMMUNITY attribute be
sent to neighbor.
Configure route map.
Configure setting rules.
Enter the router configuration mode.
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Purpose
Purpose