Aggregating Routes Advertised To Bgp4 Neighbors; Modifying Redistribution Parameters - Foundry Networks FESX Manual

FESX424 RouterD(config-bgp-router)# write memory

Aggregating Routes Advertised to BGP4 Neighbors

By default, the Layer 3 Switch advertises individual routes for all the networks. The aggregation feature allows you
to configure the Layer 3 Switch to aggregate routes in a range of networks into a single CIDR number. For
example, without aggregation, the Layer 3 Switch will individually advertise routes for networks 207.95.1.0,
207.95.2.0, and 207.95.3.0. You can configure the Layer 3 Switch to instead send a single, aggregate route for
the networks. The aggregate route would be advertised as 207.95.0.0.
NOTE: To summarize CIDR networks, you must use the aggregation feature. The auto summary feature does
not summarize networks that use CIDR numbers instead of class A, B, or C numbers.
To aggregate routes for 209.157.22.0, 209.157.23.0, and 209.157.24.0, enter the following command:
FESX424 Router(config-bgp-router)# aggregate-address 209.157.0.0 255.255.0.0
Syntax: aggregate-address <ip-addr> <ip-mask> [as-set] [nlri multicast | unicast | multicast unicast]
[summary-only] [suppress-map <map-name>] [advertise-map <map-name>] [attribute-map <map-name>]
The <ip-addr> and <ip-mask> parameters specify the aggregate value for the networks. Specify 0 for the host
portion and for the network portion that differs among the networks in the aggregate. For example, to aggregate
10.0.1.0, 10.0.2.0, and 10.0.3.0, enter the IP address 10.0.0.0 and the network mask 255.255.0.0.
The as-set parameter causes the router to aggregate AS-path information for all the routes in the aggregate
address into a single AS-path.
The nlri multicast | unicast | multicast unicast parameter specifies whether the neighbor is a multicast neighbor
or a unicast neighbor. For MBGP, you must specify multicast. Optionally, you also can specify unicast if you
want the Layer 3 Switch to exchange unicast (BGP4) routes as well as multicast routes with the neighbor. The
default is unicast only.
The summary-only parameter prevents the router from advertising more specific routes contained within the
aggregate route.
The suppress-map <map-name> parameter prevents the more specific routes contained in the specified route
map from being advertised.
The advertise-map <map-name> parameter configures the router to advertise the more specific routes in the
specified route map.
The attribute-map <map-name> parameter configures the router to set attributes for the aggregate routes based
on the specified route map.
NOTE: For the suppress-map, advertise-map, and attribute-map parameters, the route map must already be
defined. See "Defining Route Maps" on page 21-48 for information on defining a route map.

Modifying Redistribution Parameters

By default, the router does not redistribute route information between BGP4 and the IP IGPs (RIP and OSPF).
You can configure the router to redistribute OSPF routes, RIP routes, directly connected routes, or static routes
into BGP4 by using the following methods.
To enable redistribution of all OSPF routes and directly attached routes into BGP4, enter the following commands.
FESX424 Router(config)# router bgp
FESX424 Router(config-bgp-router)# redistribute ospf
December 2005 © Foundry Networks, Inc.
Configuring BGP4
21 - 37