Frame Relay Support

Unanswered Question
Jul 7th, 2008


I have one 3500 Switch and four routers (3800). I have connected all routers to switch & want to configure Frame Relay between Routers. I know how to configure FR between routers (point to multipoint). But I have no idea how to configure Switch. I have no idea how to configure DLCI on switch so that routers can be configured for the same. I am only concerned about FR Switch configuration (Hub). Please help me.

I have this problem too.
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Kevin Dorrell Mon, 07/07/2008 - 05:35

Rupesh, it sound like there is a misunderstanding here.

A Frame Relay switch is not like an Ethernet switch. It is a router chassis with lots of serial interfaces, configured to switch serial FR DLCIs. So your 3500 Ethernet switch is probably not what you are looking for.

Do any of your routers have several serial interfaces, and cpould you sacrifice that router for a FR switch? If not, you could buy yourself something cheap like a 2520 router, which makes an admirable 4-way FR switch. Of course, each of your 3800 routers will need a serial interface to connect as an FR DTE, and you will need back-to-back cables.

Kevin Dorrell


Rupesh Kashyap Mon, 07/07/2008 - 06:05

Ok Kevin,

I have one 7200 series router for Hub & 3800 router for spokes. I have four spokes. I know the configuration on Spokes, but could not understand the configuration of Hub. How can I give DLCI circuit number to spokes and all other related thing.

Paolo Bevilacqua Mon, 07/07/2008 - 06:10

Have you read my message above ?

Have you read the "frame relay switching" manual ?

Which 3800 router are you talking about? 3801 or 38x5 ?

Rupesh Kashyap Mon, 07/07/2008 - 06:16


It is 3801, beside this , I have 2821 series router also. I am only concerned with Centralize Hub configuation. Please help me.

Paolo Bevilacqua Mon, 07/07/2008 - 06:17

Is this a lab that you are trying to do? What is the actual goal ?

As Kevin said, you cannot do Frame Relay without serial connections.

Rupesh Kashyap Mon, 07/07/2008 - 06:19


I have multiple serial connection on the Hub router (7200 series), how can I configure Hub.

jamesl0112 Mon, 07/07/2008 - 07:30

Please note that the term hub would usually be interpreted as being part of a hub-and-spoke setup, which is different to a frame-relay switch.

If you have a router that you want to use as a frame-relay switch, you have to first enable this:

Router(config)#frame-relay switching

You then have to configure each interface to route from one DLCI to another:

interface Serial1/0

no ip address

encapsulation frame-relay

frame-relay intf-type dce

frame-relay route xxx interface Serialy/y zzz

xxx: incoming DLCI

Serialy/y: exit interface

zzz: outgoing DLCI

Paolo Bevilacqua Mon, 07/07/2008 - 05:36


since the connection between routers is ethernet, you can only configure FR switching over GRE tunnels. This is documented in the manual section for "Frame Relay switching".

Please rate post if it helps!


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