Frame Relay and EIGRP

Unanswered Question
Jul 19th, 2007

Hi Sir,

Please refer to attached frame relay network diagram and associated router configs.

The 4 routers are interconnected with hub-and-spoke PVCs with R4 as the hub router. All config is done at physical interfaces (no subinterfaces). I disabled FR Inverse ARP and configured static maps, in a full-mesh fashion. i.e. all 4 routers can ping to each others' serial interface IP addresses.

My questions:

(1) For spoke routers, what's the difference if the "frame-relay map" statements to other spokes contain the "broadcast" keyword and without the "broadcast" keyword. I believe it has something to do with the routing protocol we gonna run on the FR network.

(2) Given my configurations with so-called full-mesh static maps between routers, how does it affect routing protocol neighbor adjacencies? For e.g. EIGRP, are adjacencies formed between R4-R2, R4-R5 & R4-R6 or any-to-any kind of adjacencies, just like in LAN environment?

Please advise.

Thank you.

B.Rgds,

Lim TS

I have this problem too.
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royalblues Fri, 07/20/2007 - 01:12

LIM,

Broadcast keyword would be required as FR is a NBMA network and hence does not support broadcast and multicast capabilities.

Adding the broadcast keyword would allow EIGRP to communicate via hellos and establish adjancies.

Give the network, R4 will have adjacencies with all other routers and the rest will have adjacency only with R4.

Have a look at this link

http://www.cisco.com/warp/public/103/12.html#nbma

HTH, rate if it does

Narayan

mchoo2005 Tue, 07/24/2007 - 22:26

One other thing to remember is: since configuration is done on the major/physical interface, I believe you'd also have to disable split horizon, otherwise the hub router will not advertise EIGRP-learned routes from one spoke router to other spokes.

limtohsoon Tue, 07/24/2007 - 22:36

Hi,

IP split horizon checking is disabled by default for Frame Relay encapsulation so routing updates will come in and out the same interface.

We don't need to disable split horizon ("no ip split-horizon") when running RIP across FR. However, for EIGRP we need to configure the command "no ip split-horizon eigrp ".

Hope this helps.

Thank you.

B.Rgds,

Lim TS

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