EIGRP Stub problems

[John_Barber]

I am trying to bring a new site into our WAN and have not come across Eigrp Stub before. I have a 3750 and the site connecting into a 6509.

I have the following on the 3750

router eigrp 1

network 10.83.234.64 0.0.0.63

network 10.91.99.0 0.0.0.63

network 10.175.154.28 0.0.0.3

eigrp stub connected summary

The 10.175.154.28 is configured on the link interfaces with .29 being the 6509 and .30 being the 3750 with default gateway set to

ip route 0.0.0.0 0.0.0.0 10.175.154.29

The 3750 is learning routes from the Eigrp on the 6509 but nothing is being passed the other way.

[Peter Paluch]

Hi John,

This is a correct EIGRP Stub behavior. A router running EIGRP stub does not advertise any EIGRP-learned routes further. This is done to prevent any other router from converging through an EIGRP stub router. Simply put, an EIGRP stub router shall be used only to advertise networks that it is capable of reaching directly but not other EIGRP-learned networks - in that case, it is not a true stub router anymore.

You can allow selected EIGRP-learned routes to "leak" from a stub router to its neighbors, however, that should be done only under controlled circumstances. See the eigrp stub leak-map command for more details.

Why would you want your stub router to leak routes, anyway?

Best regards,

Peter

[John_Barber]

Hi Peter

I want the 3750 to let the 6509 Core switch know which IP ranges are in use at that site, allowing the 6509 to then route any traffice it receives down to the 3750.

In my example above, the 10.91 is a data vlan and the 10.83 is a voice vlan.

It exaclty the same way we have done other sites connecting in to the 6509 but this is the first 3750 we have come across that uses the Stub as part of eigrp.

Regards

John.

[Peter Paluch · Accepted solution]

Hi John,

Oh I see - you are telling me that the stub router is not advertising ANY routes to the 6k, right?

This behavior should not be affected by EIGRP Stub setting. The eigrp stub summary connected command allows the stub router to actually advertise all summary and directly connected networks covered by network commands to be advertised further.

Can you perhaps post the output of the show ip eigrp topology from the 3750?

Best regards,

Peter

[John_Barber]

Hi Peter

Thats correct, no routes were being advertised out.

Due to time constraints we have had to come up with a work-around and remove eigrp from the 3750 and put static routes into our 6k. Not the best way but had to be done.

I'll close this now, thanks for your input and if we get a similar problem in the future i'll be back.

Regards

John.