Initially the eigrp router adds the routes to the local topology table from the below sources
1)The networks of the interfaces on which eigrp is enabled using the network command will be added to the topology table.
2) If eigrp neighbor command is used, then the network of the interface referenced in the neighbor command is added to the topology table.
3)If the redistribution is being done on the router, then the routes learned from redistribution in to eigrp will be added to the topology table.
Once the routes are learned from the above three sources then the eigrp router advertises these routes to its neighbor.
In eigrp, the topology data is exchanged between the neighbors using the two types of messages as mentioned below.
1)Update
2)Ack
The EIGRP Update message contains the below details.
1)Prefix
2)Prefix length
3)Metric components:bandwidth,delay,reliability and load
4)Nonmetric items:MTU and hop count
Eigrp uses 2 type of update messages
1)Full Update message
2)Partial Update message.
Full update message is used in the below scenario
1)When the neighbor first comes up.
2)If neighbors recover after a failure then full updates are exchanged between them.
Partial update message is used in the below scenerio
1)If any changes occur in the network like metric changes,links failure or recover,new neigbors advertise new topology information then the routers send partial updates.
1)The networks of the interfaces on which eigrp is enabled using the network command will be added to the topology table.
2) If eigrp neighbor command is used, then the network of the interface referenced in the neighbor command is added to the topology table.
3)If the redistribution is being done on the router, then the routes learned from redistribution in to eigrp will be added to the topology table.
Once the routes are learned from the above three sources then the eigrp router advertises these routes to its neighbor.
In eigrp, the topology data is exchanged between the neighbors using the two types of messages as mentioned below.
1)Update
2)Ack
The EIGRP Update message contains the below details.
1)Prefix
2)Prefix length
3)Metric components:bandwidth,delay,reliability and load
4)Nonmetric items:MTU and hop count
Eigrp uses 2 type of update messages
1)Full Update message
2)Partial Update message.
Full update message is used in the below scenario
1)When the neighbor first comes up.
2)If neighbors recover after a failure then full updates are exchanged between them.
Partial update message is used in the below scenerio
1)If any changes occur in the network like metric changes,links failure or recover,new neigbors advertise new topology information then the routers send partial updates.
