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frame relay question

17 years 11 months ago #16055 by black3842
I posted this in basic questions, and then realized that it's maybe not that basic of a question since there were no replies - I hope no one gets upset for the post duplication, I'm just looking for a hand in understanding this.

I've setup a frame relay network in a simulator (Netsim).

3 routers attached to cloud, 2 routers behind each of those three that at each site.

configured the frame relay as point to multipoint on physical interfaces - full mesh.

Connectivity is great, can ping each side of the cloud from the other, but, the attached networks at each site have connectivity issues because of a problem with routing updates.

When each of the 3 cloud routers send their rip update broadcasts, they only get sent out one PVC, not both, so I have routing table propagation issues.

I read that I could configure RIP neighbors, but the simulator doesn't support this. I've read that this is the fix, since point to multipoint is NonBroadcast Multiple Access. In other words, broadcast isn't supposed to work if I'm reading this right.

Here enters my confusion. What is the purpose of the broadcast keyword on your map statements, or if you let inverse arp do your DLCI to IP mappings, it automatically adds the broadcast keyword.

What does this keyword accomplish?
And is there a way to make the broadcasts actually go out of each PVC?

I've read about something called broadcast replication, but haven't been able to find any particulars on how it works or how to set it up.

I've also seen refrences to problems with split horizon, but that shouldn't affect me, because I'm not doing hub and spoke, I'm doing full mesh.

Any help would be very much appreciated. I'm doing my best to learn about frame relay.

PS - If I configure point to point on subinterfaces, everything works fine as expected - my problem is with multipoint.


17 years 10 months ago #16202 by Dove
Replied by Dove on topic Re: frame relay question

Static mappings require the use of a frame map statement. To use static mappings, turn Inverse ARP off with the no frame-relay inverse-arp statement, and configure a frame map statement for each remote destination that maps the local DLCI to the remote IP address. Frame Relay requires the broadcast keyword to send broadcasts to the remote device.

R1#conf t

R1(config)#interface serial0

R1(config-if)#no frame-relay inverse-arp

R1(config-if)#frame map ip 122 broadcast

R1(config-if)#frame map ip 123 broadcast

The syntax of the frame map statement maps the remote IP address to the local DLCI. Broadcasts will not be transmitted by default; the broadcast option must be configured.

R1#show frame map

Serial0 (up): ip dlci 122(0x7A,0x1CA0), static,


CISCO, status defined, active

Serial0 (up): ip dlci 123(0x7B,0x1CB0), static,


CISCO, status defined, active


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