Dell PowerConnect B-FCXs, Configuration Manual

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PowerConnect B-Series FCX Configuration Guide 1051
53-1002266-01
Filtering
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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.
PowerConnect(config)#route-map TAG_IP permit 1
PowerConnect(config-routemap TAG_IP)#match address-filters 11
PowerConnect(config-routemap TAG_IP)#set tag 100
PowerConnect(config-routemap TAG_IP)#router bgp
PowerConnect(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.
When you enable cooperative filtering, the Layer 3 Switch advertises this capability in its Open
message to the neighbor when initiating the neighbor session. The Open message also indicates
whether the Layer 3 Switch is configured to send filters, receive filters or both, and the types of
filters it can send or receive. The Layer 3 Switch sends the filters as Outbound Route Filters (ORFs)
in Route Refresh messages.
To configure cooperative filtering, perform the following tasks on the Layer 3 Switch and on its
BGP4 neighbor:
•
Configure the filter.
NOTE
The current release supports cooperative filtering only for filters configured using IP prefix lists.
•
Apply the filter as in inbound filter to the neighbor.
•
Enable the cooperative route filtering feature on the Layer 3 Switch. You can enable the Layer 3
Switch to send ORFs to the neighbor, to receive ORFs from the neighbor, or both. The neighbor
uses the ORFs you send as outbound filters when it sends routes to the Layer 3 Switch.
Likewise, the Layer 3 Switch uses the ORFs it receives from the neighbor as outbound filters
when sending routes to the neighbor.
•
Reset the BGP4 neighbor session to send and receive ORFs.
•
Perform these steps on the other device.
NOTE
If the Layer 3 Switch has inbound filters, the filters are still processed even if equivalent filters have
been sent as ORFs to the neighbor.
Enabling cooperative filtering
To configure cooperative filtering, enter commands such as the following.