Brocade TurboIron 24X Series Configuration Guide - Manual (Page 753)

Brocade TurboIron 24X Series Configuration Guide 719
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Filtering
The first command configures a community ACL containing community numbers 12:99 and 12:86.
The remaining commands configure a route map that matches on routes whose destination
network is specified in ACL 1, and deletes communities 12:99 and 12:86 from those routes. The
route does not need to contain all the specified communities in order for them to be deleted. For
example, if a route contains communities 12:86, 33:44, and 66:77, community 12:86 is deleted.
Syntax: set comm-list <ACL> delete
The <ACL> parameter specifies the name of a community list ACL.
Using a table map to set the rag value
Route maps that contain set statements change values in routes when the routes are accepted by
the route map. For inbound route maps (route maps that filter routes received from neighbors), this
means that the routes are changed before they enter the BGP4 route table.
For tag values, if you do not want the value to change until a route enters the IP route table, you can
use a table map to change the value. A table map is a route map that you have associated with the
IP routing table. The Layer 3 Switch applies the set statements for tag values in the table map to
routes before adding them to the route table.
To configure a table map, you configure the route map, then identify it as a table map. The table
map does not require separate configuration. You create it simply by calling an existing route map a
table map. You can have one table map.
NOTE
Use table maps only for setting the tag value. Do not use table maps to set other attributes. To set
other route attributes, use route maps or filters.
To create a route map and identify it as a table map, enter commands such as following. These
commands create a route map that uses an address filter. For routes that match the address filter,
the route map changes the tag value to 100. This route map is then identified as a table map. As a
result, the route map is applied only to routes that the Layer 3 Switch places in the IP route table.
The route map is not applied to all routes. This example assumes that address filter 11 has already
been configured.
TurboIron(config)#route-map TAG_IP permit 1
TurboIron(config-routemap TAG_IP)#match address-filters 11
TurboIron(config-routemap TAG_IP)#set tag 100
TurboIron(config-routemap TAG_IP)#router bgp
TurboIron(config-bgp-router)#table-map TAG_IP
Configuring cooperative BGP4 route filtering
By default, the Layer 3 Switch performs all filtering of incoming routes locally, on the Layer 3 Switch
itself. You can use cooperative BGP4 route filtering to cause the filtering to be performed by a
neighbor before it sends the routes to the Layer 3 Switch. Cooperative filtering conserves resources
by eliminating unnecessary route updates and filter processing. For example, the Layer 3 Switch
can send a deny filter to its neighbor, which the neighbor uses to filter out updates before sending
them to the Layer 3 Switch. The neighbor saves the resources it would otherwise use to generate
the route updates, and the Layer 3 Switch saves the resources it would use to filter out the routes.