Blade ICE G8124-E Manuale Utente

BMD00220, October 2010

Chapter 19: Border Gateway Protocol  

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Aggregation is the process of combining several different routes in such a way that a single route 
can be advertised, which minimizes the size of the routing table. You can configure aggregate routes 
in BGP either by redistributing an aggregate route into BGP or by creating an aggregate entry in the 
BGP routing table.

To define an aggregate route in the BGP routing table, use the following commands: 

An example of creating a BGP aggregate route is shown in 

In addition to running multiple routing protocols simultaneously, BLADEOS software can 
redistribute information from one routing protocol to another. For example, you can instruct the 
switch to use BGP to re-advertise static routes. This applies to all of the IP-based routing protocols.

You can also conditionally control the redistribution of routes between routing domains by defining 
a method known as route maps between the two domains. For more information on route maps, see 

. Redistributing routes is another way of providing policy 

control over whether to export OSPF routes, fixed routes, and static routes. For an example 
configuration, see 

Default routes can be configured using the following methods:

Import

Originate—The router sends a default route to peers if it does not have any default routes in its 
routing table.

Redistribute—Default routes are either configured through the default gateway or learned via 
other protocols and redistributed to peer routers. If the default routes are from the default 
gateway, enable the static routes because default routes from the default gateway are static 
routes. Similarly, if the routes are learned from another routing protocol, make sure you enable 
that protocol for redistribution.

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