Redistributing Ibgp Routes Into Rip And Ospf; Filtering Specific Ip Addresses - Foundry Networks FESX Manual

Foundry Configuration Guide for the FESX, FSX, and FWSX
To re-enable re-advertisement, enter the following command:
FESX424 Router(config-bgp-router)# readvertise

Redistributing IBGP Routes into RIP and OSPF

By default, the Layer 3 Switch does not redistribute IBGP routes from BGP4 into RIP or OSPF. This behavior
helps eliminate routing loops. However, if your network can benefit from redistributing the IBGP routes from BGP4
into OSPF or RIP, you can enable the Layer 3 Switch to redistribute the routes. To do so, use the following CLI
method.
To enable the Layer 3 Switch to redistribute BGP4 routes into OSPF and RIP, enter the following command:
FESX424 Router(config-bgp-router)# bgp-redistribute-internal
Syntax: [no] bgp-redistribute-internal
To disable redistribution of IBGP routes into RIP and OSPF, enter the following command:
FESX424 Router(config-bgp-router)# no bgp-redistribute-internal
Filtering
This section describes the following:
• "Filtering Specific IP Addresses" on page 21-40
• "Filtering AS-Paths" on page 21-41
• "Filtering Communities" on page 21-45
• "Defining IP Prefix Lists" on page 21-47
• "Defining Neighbor Distribute Lists" on page 21-47
• "Defining Route Maps" on page 21-48
• "Using a Table Map To Set the Tag Value" on page 21-55
• "Configuring Cooperative BGP4 Route Filtering" on page 21-55

Filtering Specific IP Addresses

You can configure the router to explicitly permit or deny specific IP addresses received in updates from BGP4
neighbors by defining IP address filters. The router permits all IP addresses by default. You can define up to 100
IP address filters for BGP4.
• If you want permit to remain the default behavior, define individual filters to deny specific IP addresses.
• If you want to change the default behavior to deny, define individual filters to permit specific IP addresses.
NOTE: Once you define a filter, the default action for addresses that do not match a filter is "deny". To change
the default action to "permit", configure the last filter as "permit any any".
Address filters can be referred to by a BGP neighbor's distribute list number as well as by match statements in a
route map.
NOTE: If the filter is referred to by a route map's match statement, the filter is applied in the order in which the
filter is listed in the match statement.
NOTE: You also can filter on IP addresses by using IP ACLs.
To define an IP address filter to deny routes to 209.157.0.0, enter the following command:
21 - 40 © Foundry Networks, Inc. December 2005