Extreme Networks ExtremeWare XOS 10.1, Manual

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BGP Features
ExtremeWare XOS 10.1 Concepts Guide 211
Route Aggregation
Route aggregation is the process of combining the characteristics of several routes so that they are
advertised as a single route. Aggregation reduces the amount of information that a BGP speaker must
store and exchange with other BGP speakers. Reducing the information that is stored and exchanged
also reduces the size of the routing table.
Using Route Aggregation
To use BGP route aggregation:
1 Enable aggregation using the following command:
enable bgp aggregation
2 Create an aggregate route using the following commands:
configure bgp add aggregate-address {address-family [ipv4-unicast |
ipv4-multicast]} <ipaddress> {as-match | as-set} {summary-only} {advertise-policy
<policy>} {attribute-policy <policy>}
Using the Loopback Interface
If you are using BGP as your interior gateway protocol, you may decide to advertise the interface as
available, regardless of the status of any particular interface. The loopback interface can also be used for
EBGP multihop. Using the loopback interface eliminates multiple, unnecessary route changes.
BGP Peer Groups
You can use BGP peer groups to group together up to 512 BGP neighbors. All neighbors within the peer
group inherit the parameters of the BGP peer group. The following mandatory parameters are shared
by all neighbors in a peer group:
• remote AS
• source-interface
• route-policy
• send-community
• next-hop-self
Each BGP peer group is assigned a unique name when it is created. To create or delete peer groups, use
the following command:
create bgp peer-group <peer-group-name>
delete bgp peer-group <peer-group-name>
Changes made to the parameters of a peer group are applied to all neighbors in the peer group.
Modifying the following parameters will automatically disable and enable the neighbors before changes
take effect:
• remote-as
• timer
• source-interface
• soft-in-reset