The default administrative distance - AD of EIGRP internal route is 90 which is marked by the "D" symbol. The AD of an external route or considered as an external route using route distribution is 170 which is marked by the "D EX" symbol. There is also an eigrp summary route with the AD of 5. All of this can be shown with the #show ip route eigrp command.
To change the AD of EIGRP use the command:
(config)#router eigrp
(config-router)#distance eigrp
Auto summarization is a default feature at EIGRP. The purpose of this feature is used to automatically summarize the routes that are advertised through classfull network boundaries (EIGRP and RIPv2). It is therefore almost always necessary to turn this feature off in order make the router available to advertise classless networks routes by using the no auto-summary command. It is important to configure this route on the router sending the route. Remember that when applying the summarization, the adjecency goes down for a moment before it goes up again.
There are several advantages when applying a route summarization. A crucial advantage is that the route tables are getting smaller, because several routes are summarized. Another advantage is that CPU processing will be lighter, as the routes in the table are smaller.
To configure auto summarization use the following command:
(config)#int
(config-if)#ip summary-address eigrp <>
There are several ways to summarize routes where each route needs to have a specific bandwidth:
1. If there are multiple routes with the same CIRs, then add the amount of the CIRs together and use that as the minimum bandwidth needed. To set this use the command:
(config-if)#bandwidth
2. If there are multiple routes with different CIRs, then configure the route using a point to point (sub-)interface mode and assign each VC with the required CIR bandwidth value. To set this use the command on each sub-interface:
(config)#int serial point-to-point
(config-subif)#ip address
(config-subif)#bandwidth
3. There is also a possibility to configure a multipoint sub-interfaces. This can be done by adding all the CIRs from the routers. To set this use the command on the main router:
(config)#int serial multipoint
(config-subif)#bandwidth
The EIGRP can also be configured as a stub. However the stub has to be set only in the hub router. The spoke router does not need to be configured for stub (although possible) because the spoke router does not need to keep the routing table. It simply forwards all the routers to the hub router. This feature can also combat the SIA (stuck in active) problem because in stub networks, spoke routers will not be queried for routes when the hub does not have a feasible successor. To configure stub use the command:
(config)#router eigrp 100
(config-router)#eigrp stub
-- 10 February 2011 --
To change the AD of EIGRP use the command:
(config)#router eigrp
(config-router)#distance eigrp
Auto summarization is a default feature at EIGRP. The purpose of this feature is used to automatically summarize the routes that are advertised through classfull network boundaries (EIGRP and RIPv2). It is therefore almost always necessary to turn this feature off in order make the router available to advertise classless networks routes by using the no auto-summary command. It is important to configure this route on the router sending the route. Remember that when applying the summarization, the adjecency goes down for a moment before it goes up again.
There are several advantages when applying a route summarization. A crucial advantage is that the route tables are getting smaller, because several routes are summarized. Another advantage is that CPU processing will be lighter, as the routes in the table are smaller.
To configure auto summarization use the following command:
(config)#int
(config-if)#ip summary-address eigrp
There are several ways to summarize routes where each route needs to have a specific bandwidth:
1. If there are multiple routes with the same CIRs, then add the amount of the CIRs together and use that as the minimum bandwidth needed. To set this use the command:
(config-if)#bandwidth
2. If there are multiple routes with different CIRs, then configure the route using a point to point (sub-)interface mode and assign each VC with the required CIR bandwidth value. To set this use the command on each sub-interface:
(config)#int serial
(config-subif)#ip address
(config-subif)#bandwidth
3. There is also a possibility to configure a multipoint sub-interfaces. This can be done by adding all the CIRs from the routers. To set this use the command on the main router:
(config)#int serial
(config-subif)#bandwidth
The EIGRP can also be configured as a stub. However the stub has to be set only in the hub router. The spoke router does not need to be configured for stub (although possible) because the spoke router does not need to keep the routing table. It simply forwards all the routers to the hub router. This feature can also combat the SIA (stuck in active) problem because in stub networks, spoke routers will not be queried for routes when the hub does not have a feasible successor. To configure stub use the command:
(config)#router eigrp 100
(config-router)#eigrp stub
-- 10 February 2011 --
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