Frame-Relay Point-to-Point

Hi,

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?


Thanks.

you need a routing protocol between the 2 spokes if the spokes r in different subnets. If u "debug ip packet" you'll see an encapsulation faliure. In point to point frame the spokes HAVE to be in different subnets. To route between these subnets you need layer 3. Remember even though the Hub router knows about ALL the spoke subnets the TTL of an IP packet is 1. so if you just ping without layer 3, between spokes THE HUB WILL KILL THE PACKET and the ping will fail cause it wont get past the hub...and you'll get an encapsulation faliure.

hope this helps.

sorry the above answer i gave ws wrong....i'm an idiot...

the reason the 2 spokes cant ping eachother even though the hub router has all the subnets is because the spoke router DOES NOT HAVE THE DESTINATION NETWORK IN ITS ROUTING TABLE...so you will have a route lookup faliure...easily confirmed by a "debug ip packet details" command


sorry...about the wrong answer...

the TTL 1 issue would occur in a multipoint environment if no mapping ws done between spokes...which is another issue

Th

As far as I know, it is normal that a router can't ping its own IP on a frame relay PVC.I don't remember exactly the technical details behind it but I think you can see it like a kind of split horizon. Why would spoke_two send back a packet from spoke_one to spoke_one?

the reason you cant ping yourself in a multipoint frame is cause there is no automatic layer 2 to 3 mapping(inverse arp) in frame...to your OWN ip....you can easily fix that by creating a static map to your own IP with any valid DLCI...and it'll work

its not a split-horizon issue

In a hub and spoke network the hub will not be forwarding at layer 3 because layer 3 is effectively switched off by the use of the global config command frame-relay switching. I have so far been unable to configure a lab where the hub will repsond to a ping from a spoke (which was the original question) because the hub router has been turned in to a packet switch device with forwarding decisions based on the layer 2 DLCI addresses.
The spokes, whether configired as point-to-point or simply left to "normal" operation should be in the same subnet otherwise the spokes will not see each other at layer 3.