Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 451)

Using a table map to set the tag 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), 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 device 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 first configure the route map, then identify it as a table map. The table
map does not require separate configuration. 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 IP prefix list filter,
the route map changes the tag value to 100 and is then considered as a table map. This route map is
applied only to routes the device places in the IP route table. The route map is not applied to all routes.
This example assumes that IP prefix list p11 has already been configured.
device(config)# route-map TAG_IP permit 1
device(config-routemap TAG_IP)# match ip address prefix-list p11
device(config-routemap TAG_IP)# set tag 100
device(config-routemap TAG_IP)# router bgp
device(config-bgp)# table-map TAG_IP
Configuring cooperative BGP4 route filtering
By default, the device performs all filtering of incoming routes locally, on the device 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 device. Cooperative filtering conserves resources by eliminating unnecessary route
updates and filter processing. For example, the device can send a deny filter to a neighbor, which the
neighbor uses to filter out updates before sending them to the device. The neighbor saves the
resources it would otherwise use to generate the route updates, and the device saves the resources it
would use to filter out the routes.
When you enable cooperative filtering, the device advertises this capability in its Open message to the
neighbor when initiating the neighbor session. The Open message also indicates whether the device is
configured to send filters, receive filters, or both, and the types of filters it can send or receive. The
device sends the filters as Outbound Route Filters (ORFs) in route refresh messages.
To configure cooperative filtering, perform the following tasks on the device and on the BGP4 neighbor:
• Configure the filter.
NOTE
Cooperative filtering is currently supported only for filters configured using IP prefix lists.
• Apply the filter as an inbound filter to the neighbor.
• Enable the cooperative route filtering feature on the device. You can enable the device to send ORFs
to the neighbor, to receive ORFs from the neighbor, or both. The neighbor uses the ORFs you send
Using a table map to set the tag value
FastIron Ethernet Switch Layer 3 Routing Configuration Guide 451
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