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TOPIC: Frame-Relay Point-to-Point

Frame-Relay Point-to-Point 9 years 4 months ago #33556


I have configured a Frame relay scenario in GNS.
It consist of 3 routers (hub and spoke topology). They are all configured as point-to-point.

My hub router is able to ping both spoke routers, and the spoke routers are able to ping the hub router.
But my problem is that the spoke routers are not able to ping each other, is this a characteristic of point-t-point frame relay? Or I should be able to make the 2 spoke routers pingable?

Kenneth Chong

Re: Frame-Relay Point-to-Point 9 years 4 months ago #33557

Presumably the two serial interfaces on the hub router are in separate subnets? If so, then you need either a layer two or a layer three route between the two spokes. A combination of sub-interfaces with the appropriate layer three addresses along with some layer two dlci addresses and mappings should sort it, assuming I remember correctly :oops:

Re: Frame-Relay Point-to-Point 9 years 4 months ago #33583


I don't really understand what your saying...

Ok, so there are 3 routers ( hub and spoke topolgy ).
And yea they are on different subnets.

R1 = Hub
R2= Spoke
R3= Spoke

I have the basic configuration that R1 is able to ping both R2 and R3.
R2 is able to ping R1
R3 is able to ping R1

The only problem I am having now is that R3 is not able to ping R2, and I have no routing protocols running on non of the routers.
They are configured as point-to-point.

I am wondering if there is a method or command that I can use to make R2 and R3 pingable. I have heard of this frame relay mapping, but I am not sure how this is used, and I can't really find a good documentation on this...

So is this frame-relay mapping command that I have to use ?

Kenneth Chong

Re: Frame-Relay Point-to-Point 9 years 3 months ago #33737

The issue is getting a layer three route across a layer two hub.
Frame relay mapping is used if you turn off inverse arps, which you can do if you want, but it won't help with your issue.
Your hub router needs to have 4 interfaces, not just the two physical. So you need to create a sub interface on each interface of all 3 routers. Then you can map across the hub with layer 2 to layer 3 map commands on the sib-ifs. Essentially you make the hub transparent at Layer 3 whilst it provides frame relay switching at layer two. With this type of config, the two spokes will be able to ping at layer three :wink:
BUT, I need to configure this on my test lab to make 100% sure I'm not talking rubbish. But as I'm away from home right now it'll be next week, unless I can blag some time in the switch room after hours :shock:

Re: Frame-Relay Point-to-Point 9 years 3 months ago #33841

Can you show me the config for the hub, assuming you haven't sorted it already?
Can't think what I'm missing having re-visited this subject :oops:

Re: Frame-Relay Point-to-Point 9 years 3 months ago #33873

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Are you using inverse ARPs or manual ip mapping? it would be better if you posted your configuration so that we can see the problem. the problem might be because of split horizon which doesnt accept sending routing updates out the same interface on which it received another. try disabling split horizon.
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