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frame-relay - config a router as a switch

Unanswered Question
Oct 24th, 2006
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I am trying to configure a router as a frame-relay switch called R3.

R1 (S0/1) is connected to my Frame-Relay Switch R3 (S1/0). R3 has a further 3 connections (S1/1, S1/2 & S1/3) to R2, R4 &R5. So R1 uses subinterfaces.


I am having problems configuring the switch to say connect R1 to R2.


Here is my R1 config:


Interface Serial0/0

No ip address

Encapsulation frame-relay

!

interface Serial0/0.1 point-to-point

ip address 10.1.1.1 255.255.255.0

frame-relay interface-dlci 16

!

interface Serial0/0.2 point-to-point

ip address 10.1.2.1 255.255.255.0

frame-relay interface-dlci 17

!

interface Serial0/0.3 point-to-point

ip address 10.1.3.1 255.255.255.0

frame-relay interface-dlci 18



Here is my Frame-Relay switch (R3) config:


frame-relay switching

!

Interface Serial1/0

No ip address

Encapsulation frame-relay

Clock rate 64000

Frame-relay intf-type dce

!

interface Serial1/0.1 point-to-point

frame-relay interface-dlci 16

!

interface Serial1/0.2 point-to-point

frame-relay interface-dlci 17

!

interface Serial1/0.3 point-to-point

frame-relay interface-dlci 18

!

Interface Serial1/1

No ip address

Encapsulation frame-relay

Clock rate 64000

frame-relay interface-dlci 20

!

Interface Serial1/2

No ip address

Encapsulation frame-relay

Clock rate 64000

frame-relay interface-dlci 21

!

Interface Serial1/3

No ip address

Encapsulation frame-relay

Clock rate 64000

frame-relay interface-dlci 22



Here is my R2 config:


interface Serial0/0

ip address 10.1.1.2 255.255.255.0

encapsulation frame-relay

no fair-queue

frame-relay interface-dlci 20



Normally I would enter the frame-relay switch command?


Frame-relay route 16 interface s1/1 20


I want to use subinterrfaces and not multipoint.

Why does this not work?? I cannot get connectivity from R1 to R2!














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Richard Burts Tue, 10/24/2006 - 09:17
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John


It is fine to use subinterfaces on R1 and R2 (in fact it is best practice to use point to point subinterface for Frame Relay). But I do not believe that you can do subintefaces on the router that is acting as the switch. I believe that the key elements of the router as frame relay switch include: frame-relay switching (which you have), Frame-relay intf-type dce (which you have), and Frame-relay route 16 interface s1/1 20 (which you need to add in place of the subinterfaces with DLCI identifier).


HTH


Rick

johnross400 Tue, 10/24/2006 - 09:49
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Thanks Rick


Does this then mean that for a home lab set-up it is not possible to create a lab exercise using frame-relay subinterfaces on R1 if that router is connected to another router, on say S0/0, which is configured as a F-R switch?

I see many examples of Frame Relay but almost all assume the frame-relay is already preconfigured and working!

Richard Burts Tue, 10/24/2006 - 13:09
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John


I believe that your original post described the situation in terms of R1 and R2 routers configured for Frame Relay and using R3 as the Frame Relay switch. In that situation R1 and R2 can certainly configure Frame Relay with point to point subinterfaces. As I said in my response I do not believe that it is possible to use subinterfaces on the router which is acting as the Frame Relay switch.


HTH


Rick

s-sheffield Tue, 10/24/2006 - 23:20
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Hi


I've had to dig deep into some of my works test suite lab configs.


I did manage to build a FR switch using sub-interfaces (on an old 3620). The only difference from your config is the fact that for my point-to-point sub-ints, I used 30 bit addressing for the links.


HTH


Stu

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