frame-relay and clns

Hi,

I understand why you would use frame-relay map ip <address> <dlci> <broadcast>,
also that you would use the broadcast keyword to send out received broadcasts as unicasts (i suspect) to the remote site.

But whats up with frame-relay map clns <dlci>... I thought CLNP was the layer-3 protocol for CLNS (which i understand to be like the full tcp/ip suite).

Can someone clarify this for me. It doesnt seem to be used on point-to-point links though. The self-study guide doesnt go into this at all.

Thanks!

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Comments

scheistermeister

What exactly are you trying to do? Use IS-IS on non-broadcast frame-relay?

astorrs

It's used to forward broadcasts in IS-IS networks (which are popular with service providers). Cisco has some good articles here and here covering more details of their implementation. There is also a good PPT on the subject here if that's more your kind of thing.

kpjungle

astorrs:
Thanks for the links.

scheistermeister:
Yeah. I dont quite understand why its nessecary. I read it on some blog, and the guy set up these frame maps on multipoint interfaces. But on point-to-point interfaces it doesnt seem to need it, and im not sure why.

With standard IP based routing, when you set up a point-to-point link, the subnet you assign it are automatically connected to the DLCI you give the subinterface, but you dont give any "CLNS" address to the subinterface here.

http://ccnprecertification.com/2004/03/26/is-is-multiareas-and-frame-relay/

Plazma

point-to-multipoint + ISIS = big honkin' mess.. its possible, but definitively should be avoided.

kpjungle

Plazma wrote:

point-to-multipoint + ISIS = big honkin' mess.. its possible, but definitively should be avoided.

Yeah it seems so

.

However, it seems to be nessecary to specify the "frame-relay map clns <dlci> broadcast" when using multipoint interfaces with IS-IS, otherwise you simply wont see any CLNS neighbors.

But a mess, I agree, all NBMA is for me

Let me ask a follow up question. In the lab portfolio, it asks regarding ISIS and Frame-relay. What transport protocol does ISIS use? my guess is it uses direct datalink encapsulation, is that wrong?