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View Full Version : Why do I receive a /32 prefix route in EIGRP?


David.C
06-17-2009, 01:57 AM
Hi, all
Why do we receive a /32 prefix with EIGRP ?



example :

Rack1SW1#sho ip route eigrp
129.1.0.0/16 is variably subnetted, 8 subnets, 3 masks
D 129.1.3.128/25 [90/2172672] via 129.1.17.1, 00:00:16, Vlan17
D 129.1.3.0/25 [90/2172672] via 129.1.17.1, 00:00:16, Vlan17
D 129.1.13.0/24 [90/2170112] via 129.1.17.1, 00:00:16, Vlan17
D 129.1.13.3/32 [90/2170112] via 129.1.17.1, 00:00:16, Vlan17
D 129.1.23.2/32 [90/2682112] via 129.1.17.1, 00:00:16, Vlan17
D 129.1.23.0/24 [90/2682112] via 129.1.17.1, 00:00:16, Vlan17
150.1.0.0/24 is subnetted, 4 subnets
D 150.1.3.0 [90/2298112] via 129.1.17.1, 00:00:17, Vlan17
D 150.1.2.0 [90/2810112] via 129.1.17.1, 00:00:17, Vlan17
D 150.1.1.0 [90/130816] via 129.1.17.1, 00:00:17, Vlan17



I mean why do we get the /32 routes and when ?

thanks

Chris
06-17-2009, 02:34 AM
My guess would be PPP that happens to be exchanging a peer neighbor-route.

You have /32 AND /24 there.

http://www.netbraintech.com/share/eigrp32bitroute_reply.gif

David.C
06-17-2009, 06:34 AM
thanks, Chris.

as a matter of fact i am running PPP but why do i advertise them in EIGRP ?

Chris
06-17-2009, 06:35 AM
Because, most likely, in your EIGRP configuration you put the "network" command with the /24 mask which encompasses EVERY link within that range.

So, if you had:

10.1.12.0/24 as your subnet
10.1.12.1 on your router
10.1.12.2 on the other router

Your "show ip route connected" would look like:

C 10.1.12.0/24 Serial1/0
C 10.1.12.1/32 Serial1/0

If you put "network 10.1.12.0 0.0.0.255" under router eigrp, you'd get both.

If you put "network 10.1.12.1 0.0.0.0" under router eigrp, you'd only get the /24 network!