EIGRP Stub

[alsayed]

HI All!

if R1 sent summary To The core router.can R1 Act as EIGRP Stub?WHEN WE need to configure STUB?

[vijayasankar]

Check out this URL, which has example scenario also depicted to explain the EIGRP stub router functionality.

http://www.cisco.com/en/US/tech/tk365/technologies_white_paper0900aecd8023df6f.shtml

-VJ

[gpulos]

yes, if R1 needs to send a summary it can still be configured as a stub with the command:

eigrp stub summary

this will configure the spoke site router, R1, for eigrp stub operation. this eigrp stub will only advertise 'summary' routes.

[alsayed]

Hi

Here in my attachment;every switch sent summary routes via int port-channel outgoing interface to the CORE.do i need to configure each Dist as eigrp stub?

10xs

[Richard Burts]

Ali

There are a couple of things in your drawing that I need to clarify:

- you show some devices (1U) connected to DSx but it is not clear what kind of device that is. I am assuming that it is just a layer 2 switch. But if that is not correct it could change the answer to your question.

- your drawing shows DS1 and DS2 both being in 10.11.0.0 and connected to each other as well as connected to the core. If this is true then neither DS1 nor DS2 should be configured as EIGRP stub.

- your drawing shows DS3 in 10.13.0.0 and another DS3 in 10.14.0.0. Is that a mistake? Should it be DS3 and DS4? The drawing shows that they are not interconnected. If that is accurate then both of them can be configured as EIGRP stub.

The important aspect that controls whether a router should be configured as stub is whether there is a routing neighbor that might need to come through the router to get upstream. In the case of DS1 and DS2, if the link from DS2 to the core failed, then DS2 needs to advertise through DS1 to be reachable from the core. Therefore neither DS1 nor DS2 should be configured as EIGRP stub.

Another way of explaining it is that if a router receives updates from one neighbor and needs to forward those updates to another neighbor then it should not be configured as stub. The only routers that should be configured as EIGRP stub are routers whose advertisements are all things that it knows locally.

HTH

Rick

[alsayed]

Hi!

the devices(Distribution) are 6509-sup1;the core is 6509-sup20.

10xs

[alsayed]

Hi rburts!

i appreciated ur explanation;but what do u mean by this"configured as EIGRP stub are routers whose advertisements are all things that it knows locally"

10xs

[Richard Burts]

Ali

What I meant was that if everything the router is advertising is local to that router (its own connected interfaces, or summarization configured on its interfaces, or local static routes which are redistributed) then it is ok to configure it as EIGRP stub. But if a router learns anything dynamically from one neighbor and needs to advertise that to some other neighbor then it should not be configured as EIGRP stub.

HTH

Rick

[ruwhite]

In 12.3(10.2)T, there is a new command, leak-map, which allows you to leak routes between two routers in a single site, so both of them can be stub to the hub/distribution layer, and not stub towards each other. I don't think there's any docs on CCO yet--it's on my todo list. *sigh*

Not that I jump in here that much any more (maybe when I finish working on a big project I'm currently wrapped up in), but thought I'd share that information.

:-)

Russ.W