EIGRP Add Path Support


(Rene Molenaar) #1

This topic is to discuss the following lesson:


(Dawn W) #4

Hi Rene,

Hub(config-router-af-interface)#add-paths <1-4> "Number of add paths to be advertised"
Can you explain more about when we use the number of 1, 2, 3, or 4?
Even though I tested with add-paths of 1-2-3-4, the result’s nothing change.

Spoke1#sho ip route eigrp 
D     192.168.34.0/24 [90/102405120] via 172.16.123.4, 00:01:42, Tunnel0
                      [90/102405120] via 172.16.123.3, 00:01:42, Tunnel0

(Lazaros Agapides) #5

Hello Dawn

The add-paths is used when you have multiple paths from the hub to a specific network that can be reached via multiple spokes. EIGRP however advertises only one path as the best path to connected spokes. The add-paths command allows EIGRP to advertise up to an additional four. This will only be seen if multiple paths are present to the same network.

For the topology in question:


As can be seen, there are two routes to the 192.168.12.0/24 network, via Spoke1 and Spoke2. The hub will have only one route to this network by default. The add-paths command will allow both the Spoke1 and Spoke2 route be added in the routing table.

More information on the add-paths command can also be found at this Cisco documentation.


I hope this has been helpful!

Laz


(Dawn W) #6

Hi Laz,

Thanks for your kind explanation.
I understood.