EIGRP || Advertise Loopback as /32 instead of /24 ||

[aantonis]

Hello everyone,
Assuming that we have 2 routers as EIGRP neighbors directly connected via the Gi0/0.

R1 is configured with a Loopback IP (192.168.1.1/24).

I would like to ask if there is a way to advertise two separate routes to R2:

 1. one route for 192.168.1.0/24
 2. one route for 192.168.1.1/32

In other worlds, i would like to include the /32 Loopback1 in the EIGRP route domain and the /24 Network simultaneously.

Configuration as follows:

R1

!

int Lo1

 ip add 192.168.1.1 255.255.255.0

int Gi0/0

 ip add 172.28.12.1 255.255.255.0

!

router eigrp 12

 no auto

 passive-interface default
 no passive-interface Gi0/0
 net 172.28.12.0 0.0.0.255
 net 192.168.1.0 0.0.0.255

R2

!

int Gi0/0

 ip add 172.28.12.2 255.255.255.0

!

router eigrp 12

 no auto 

 passive-interface default
 no passive-interface Gi0/0
 net 172.28.12.0 0.0.0.255 

 ---------------------------

P.S: In case the Loopback is configured as /32 this can be accomplished using summary-address & leak-map.

This solution has been discussed in the threat 

 https://community.cisco.com/t5/routing/eigrp-advertise-loopback-and-network-simultaneously/m-p/3784999#M308088

Here, I am looking for a solution in case the Loopback is configured as /24

Thanks

[Richard Burts]

I am not clear why you would want to advertise both 192.168.1.0/24 and 192.168.1.1/32. But if you want to do this I would think that a static route ip route 192.168.1.1 255.255.255.255 null0 (or some other next hop) and under router eigrp redistribute static should accomplish what you want.

HTH

Rick

[Sergey Lisitsin]

Richard, that won't work because of the "L" type route on the source router. The "L" route will always be preferred, because it has AD of 0, being type "Connected", so static to Null0 will lose. I don't think there is a way to advertise that.

[Sergey Lisitsin]

A. Androul, unfortunately I don't think there is a solution for such a case. Is there a reason for such a strange requirement or is it just a lab exercise?

[aantonis]

Hi Sergey, this "strange" requirement is part of a lab exercise.

[Sergey Lisitsin]

Well, in that case I'll just say it is not possible and it is not a correct design. Correct one would be to use /32 as an address on the loopback and then summary to advertise a shorter prefix. :-) Or if you want to get totally mad, you can probably use BGP in this scenario. BGP will advertise the prefix even if it doesn't use it itself, as long as it is valid. Try that with BGP instead.