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Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
OL-9639-07
Chapter 35 Configuring IP Unicast Routing
Configuring BGP
Configuring BGP Filtering with Route Maps
Within BGP, you can use route maps to control and to modify routing information and to define the
conditions by which routes are redistributed between routing domains. See the
“Using Route Maps to
Redistribute Routing Information” section on page 35-99
for more information about route maps. Each
route map has a name that identifies the route map (
map tag
) and an optional sequence number.
Beginning in privileged EXEC mode, follow these steps to use a route map to disable next-hop
processing:
Use the
no route-map
map-tag
command to delete the route map. Use the
no set ip next-hop
ip-address
command to re-enable next-hop processing.
Configuring BGP Filtering by Neighbor
You can filter BGP advertisements by using AS-path filters, such as the
as-path access-list
global
configuration command and the
neighbor filter-list
router configuration command. You can also use
access lists with the
neighbor distribute-list
router configuration command. Distribute-list filters are
applied to network numbers. See the
“Controlling Advertising and Processing in Routing Updates”
section on page 35-107
for information about the
distribute-list
command.
You can use route maps on a per-neighbor basis to filter updates and to modify various attributes. A route
map can be applied to either inbound or outbound updates. Only the routes that pass the route map are
sent or accepted in updates. On both inbound and outbound updates, matching is supported based on AS
path, community, and network numbers. Autonomous-system path matching requires the
match
as-path
access-lis
t route-map command, community-based matching requires the
match community-list
route-map command, and network-based matching requires the
ip access-list
global configuration
command.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
route-map
map-tag
[[
permit
|
deny
] |
sequence-number
]]
Create a route map, and enter route-map configuration mode.
Step 3
set ip next-hop
ip-address
[
...ip-address
]
[
peer-address
]
(Optional) Set a route map to disable next-hop processing
•
In an inbound route map, set the next hop of matching routes to
be the neighbor peering address, overriding third-party next hops.
•
In an outbound route map of a BGP peer, set the next hop to the
peering address of the local router, disabling the next-hop
calculation.
Step 4
end
Return to privileged EXEC mode.
Step 5
show route-map
[
map-name
]
Display all route maps configured or only the one specified to verify
configuration.
Step 6
copy running-config startup-config
(Optional) Save your entries in the configuration file.
Summary of Contents for ME 3400 Series
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