How to configure Frame-Relay Point-to-Multipoint

(Rene Molenaar) #1

This topic is to discuss the following lesson:

(Rene Molenaar) #2

Thanks it were really helpful information.

(system) #3

many thanks for the article; however the spoke-spoke mappings at the end of the article are not correct and we need a new DLCI mapping other than the one already used

If I use the mappings defined here, when pinging from Spoke1-Spoke2 (and vice verca) I get UUUUU. Changing the mappings to 2:221-3:321 on the switch and the spoke configs solved the problem

Spoke1 - frame-relay map ip 192.168.123.3 221
Spoke 2 - frame-relay map ip 192.168.123.2 321

(Rene Molenaar) #4

Hi Usman,

In your case you added another PVC between Spoke1 and Spoke2 which will work but it’s not required.

My example above is a hub and spoke example, if your mappings are correct you can ping between Spoke1 and Spoke2 through the hub router.

Rene

(system) #5

thanks for the clarification. It does work now :slight_smile:

(Rene Molenaar) #6

Glad to hear you got it working.

(system) #7

I get you now thanks so much.

(christopher c) #8

I did went through this with you in GNS3 and it worked great. One question, when adding the “frame-relay map ip 2.2.2.2 301”, you didn’t use the broadcast at the end?

(Rene Molenaar) #9

Hi Chris,

You will need the broadcast parameter if you want to send multicast or broadcast traffic. If you need an additional frame-relay map for spoke-to-spoke unicast traffic then you don’t have to add it.

Rene

(Hussein Samir) #10

Hi Rene,

If we disable the split-horizon so how you can solve the counting to infinity problem ?

thanks

(Hussein Samir) #11

And what is the benefit of using sub-interfaces in Frame-Relay Point-to-Multipoint ?

(Rene Molenaar) #12

Hi Hussein,

It could be useful if you have a mix of point-to-point and point-to-multipoint. In that case, you will have to use sub-interfaces. If you only have point-to-multipoint then you might just as well use the physical interface.

Rene

(Rene Molenaar) #13

Well, we still have route poisoning and poison reverse. Also, when we use RIP…a hop count of 16 is considered as unreachable.

(kam a) #14

Hi Rene,

Just wondering, why do we use the keyword “multipoint” when configuring point to multipoint on subinerfaces, but no on physical interfaces?

Thanks,

(Rene Molenaar) #15

Hi Kam,

Frame-relay physical interfaces are always multipoint so that’s why you don’t have to configure it. Sub-interfaces could be point-to-point or multipoint.

Rene

(Edwin B) #16

Hello Rene,

If a pvc has been created between hub-spoke1 and hub-spoke2, how is the traffic from spoke2 to spoke1 going to get to spoke1 by just creating mappings between spoke2 and spoke1?? Should the route table for spoke2 point to 192.168.123.1 as the route to reach 2.2.2.2 on spoke1 via the pvc since this is the next hop in its path? Then should Hub route the traffic via its pvc to reach 2.2.2.2 on spoke1?

If not, how does the Frame Relay switch know to pass data between spoke2 and spoke1 if a pvc has not been created between a dlci on spoke2 and dlci on spoke1?

 

 

 

(Rene Molenaar) #17

Hi Edwin,

If you want connectivity between the IP addresses on the spoke routers’ frame-relay interfaces then all you need are frame-relay maps. For examples these two:

Spoke1(config-subif)#frame-relay map ip 192.168.123.3 201
-

Spoke2(config-subif)#frame-relay map ip 192.168.123.2 301

When spoke1 wants to reach 192.168.123.3 then it will forward it on the PVC that has DLCI 201 so it will end up at the hub router. The hub router will be able to forward it to spoke2.

The frame-relay switch is a just a dumb box…it only knows how to switch from one DLCI to the other, that’s it.

About 2.2.2.2…this really depends on the routing protocol that you use. For example, if you use OSPF broadcast or non-broadcast then the next hop IP address will always be the spoke router. In this case, you have to create a frame-relay map so the spoke routers know how to reach each other’s next hop IP addresses.

If you use OSPF point-to-multipoint (non-broadcast) then the next hop IP address will be changed to the hub. In this case, the spoke routers only require a frame-relay map for the hub.

Hope this helps :slight_smile:

Rene

(PALANIAPPAN M) #18

Hi Rene

I tried the above set up in GNS3 lab. I did not use “no ip split-horizon” command on Hub router but the RIP route for 2.2.2.0/24 showed up on Spoke2 router.
Is this normal?

Thanks
Palani

(Rene Molenaar) #19

Hi Palani,

You might want to check if no split horizon is the default on your router. Try a show run all | include split to see what the default setting is.

Rene

(sims) #20

Hi
Why I cant ping from spoke 1 to spoke 2 .
How to do that

Thanks