EIGRP issues to advertise a not-directly-connected route

[liewtienqing]

Hi All,

I think I'm having a gap in my knowledge here..

PROBLEM:

Office 10.10.0.0/16 and 10.20.0.0/16, two uplinks (MPLS and VPN).

Running EIGRP over the tunnel interfaces only.

EIGRP is not advertising a network that isn't directly connected, is this due to the static summary route?

CONFIG

ip route 10.0.0.0 255.0.0.0 10.255.255.1 (MPLS)
ip route 10.10.0.0 255.255.0.0 192.168.1.254 (Office LAN)
ip route 10.20.0.0 255.255.0.0 192.168.1.254 (Office LAN)

interface Tunnel10
description 2ND_UPLINK
ip address 172.16.0.10 255.255.255.0

router eigrp TEST
addr ipv4 autonomous 10
af-interface default
passive-interface
af-interface tunnel10
no passive

network 172.16.0.0 0.0.0.255
network 10.10.0.0 0.0.255.255
network 10.20.0.0 0.0.255.255
no auto-summary

Show IP Protocols confirms the networks are advertised, and auto summarization is disabled.

But neighbor router is able to learn of 172.16.0.0/24, but not the 10.10.0.0/16 nor 10.20.0.0/16

[Sergiu.Daniluk]

Hi @liewtienqing 

My EIGRP knowledge is rusty, long time not working with it, but I believe the problem with the current config, when using network statement, is because the static routes are pointing to next-hop. If you will change the static routes to point to egress interface, the routes will be advertised. If not, alternatively, use "redistribute static" command under eigrp config.

Stay safe,

Sergiu

[paul driver]

Hello
The network command enables eigrp on the connected interfaces, You need to redistribute those static routes instead, This then should advertise them.

[Richard Burts · Accepted solution]

I believe that both suggestions might work. But while changing the static routes to specify outbound interface instead of next hop might cause the subnets to be advertised it creates a new set of problems. 

- it forces the router to arp for every remote destination reached by this route.

- it works only if the next hop device supports proxy arp and fails if the device does not support proxy arp  

- it consumes more bandwidth because of the extra arp requests. 

- it consumes more memory because of the larger arp table. 

The configuration of EIGRP includes network statements for the 2 networks. This would work if the networks were locally connected. But the static routes suggest that the networks are remote. If the networks really are remote then solve the problem by redistribute static and remove the unnecessary network statements. 

[liewtienqing]

Thanks Sergei, Paul & Rick!

Applied a prefix list and redistribute static and it works like a charm.

ip prefix-list PL_1 permit 10.10.0.0/24
ip prefix-list PL_1 permit 10.20.0.0/24

router eigrp TEST
topology base
distribute-list prefix PL_1 out
redistribute static