Frame Relay Switch - Subinterfaces

[kevwilson6411]

Hi

If a frame relay switch (Cloud)  is connected to other routers with a point to point configuration using sub-interfaces, does the frame relay switch interfaces require subinterfaces to match?

Many thanks

[Peter Paluch · Accepted solution]

Hi Kevin,

No, a Frame Relay switch does not even have subinterfaces, regardless of the end router configuration (multipoint or point-to-point). This is a sample configuration of a Frame Relay switch, it will make things a little easier to understand:

frame-relay switching
interface Serial0/0
 description => To R1 - Hub router <=
 encapsulation frame-relay
 frame-relay intf-type dce
 frame-relay route 102 interface Serial0/1 201
 frame-relay route 103 interface Serial0/2 301
!
interface Serial0/1
 description => To R2 - Spoke router <=
 encapsulation frame-relay
 frame-relay intf-type dce
 frame-relay route 201 interface Serial0/0 102
!
interface Serial0/1
 description => To R3 - Spoke router <=
 encapsulation frame-relay
 frame-relay intf-type dce
 frame-relay route 301 interface Serial0/0 103

This configuration is a typical hub-and-spoke configuration where R1 has PVCs to routers R2 and R3, while routers R2 and R3 have only a single PVC towards the hub router R1. Note that regardless of how many PVCs are configured on an interface, a Frame Relay switch does not use subinterfaces.

Please feel welcome to ask further!

Best regards,

Peter

[kevwilson6411]

Peter,

Many thanks,

I configured a multipoint network yesterday at it work fine, so I have now decided to configure a point to point network. I must have missed or configured something wrong. I will investigate it further. I just wanted to rule out having to map potential sub-interfaces on the frame relay switch to the sub-interfaces of the end routers. Since they dont have sub-interfaces this is impossible.

Regards

Kev

[Peter Paluch]

Hello Kevin,

If you have a configuration that does not seem to work please post it here and also include the output of show frame-relay pvc command.

Best regards,

Peter

[kevwilson6411]

Hi Peter,

All the config seemed to be ok, but I had one of the PVC coming up as inactive. I deleted all the frame-relay config on the router and then reconfigured it. All is now working, on of those odd networking moments.

I am studying for CCNP route, and I have spent more time learn frame relay then any of the offical sylabus. Now my frame relay issue is fixed, I can start.

Thanks for you assistance

Regards

Kev