Configuring Frame Relay switch in test lab

Answered Question
Nov 8th, 2008
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I've been trying to set up a frame switch for my home lab and would like to know if anyone may be able to help. None of my frame-relay PVCs are active and I'm wondering what I am doing wrong.


1) For the frame switch I am using a 2610 with c2600-ik9o3s3-mz.123-21.bin and three WIC-1DSU-T1 cards (one for each branch)

2) The branch routers are 2811 with WIC-1DSU-T1-V2

3) The connections are all crossover T1 and layer 1 is working


I can't seem to find any good documentation on setting this up properly, any wisdom is very much appreciated.


On Frame Relay switch

!

frame-relay switching

!

interface Serial0/0

description HQ

no ip address

encapsulation frame-relay

no fair-queue

frame-relay lmi-type cisco

frame-relay intf-type dce

frame-relay route 101 interface Serial1/0 103

frame-relay route 102 interface Serial1/1 104

!

interface Serial1/0

description BR1

no ip address

encapsulation frame-relay

no fair-queue

frame-relay lmi-type cisco

frame-relay intf-type dce

frame-relay route 103 interface Serial0/0 101

!

interface Serial1/1

description BR2

no ip address

encapsulation frame-relay

no fair-queue

frame-relay lmi-type cisco

frame-relay intf-type dce

frame-relay route 104 interface Serial0/0 102





On HQ router


interface Serial0/1/0

no ip address

encapsulation frame-relay

no keepalive

frame-relay lmi-type cisco

!

interface Serial0/1/0.1 point-to-point

ip address 172.16.100.1 255.255.255.252

snmp trap link-status

frame-relay interface-dlci 101

!

interface Serial0/1/0.2 point-to-point

ip address 172.16.100.5 255.255.255.252

snmp trap link-status

frame-relay interface-dlci 102




On BR1 router


interface Serial0/1/0

no ip address

encapsulation frame-relay

no keepalive

frame-relay lmi-type cisco

!

interface Serial0/1/0.1 point-to-point

ip address 172.16.100.2 255.255.255.252

snmp trap link-status

frame-relay interface-dlci 103



On BR2 router


interface Serial0/0/0

no ip address

encapsulation frame-relay

no keepalive

frame-relay lmi-type cisco

!

interface Serial0/0/0.1 point-to-point

ip address 172.16.100.6 255.255.255.252

frame-relay interface-dlci 104








Correct Answer by Richard Burts about 8 years 6 months ago

Shikamaru


I see that on your HQ and Branch routers you have configured the serial interfaces with no keepalive. I suggest that you change that. LMI is the keepalive mechanism for Frame Relay and if you turn off keepalives, then LMI does not function and the routers never learn their PVCs from the Frame Relay switch.


I also notice that while you do have the Frame Relay interface type dce, which is needed, that you do not have any physical interface as dce and no router is configured to provide clocking. If these routers are connected back to back then someone needs to provide clocking.


HTH


Rick

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Correct Answer
Richard Burts Sat, 11/08/2008 - 15:29
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Shikamaru


I see that on your HQ and Branch routers you have configured the serial interfaces with no keepalive. I suggest that you change that. LMI is the keepalive mechanism for Frame Relay and if you turn off keepalives, then LMI does not function and the routers never learn their PVCs from the Frame Relay switch.


I also notice that while you do have the Frame Relay interface type dce, which is needed, that you do not have any physical interface as dce and no router is configured to provide clocking. If these routers are connected back to back then someone needs to provide clocking.


HTH


Rick

shikamarunara Sat, 11/08/2008 - 18:30
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Rick,

Your first suggestion solved the problem. In reviewing some example configs that were posted on some sites, people made mention that keepalives would cause issues and that they should be disabled. I think that the syntax will cause problems when the routers are configured for DCE/DTE cables, in my set up not so much.


You would think that clocking should be configured, but this set up works fine without it (not sure why, but it works.)


Now, my only regret is that I can't give you more points than the maximum for solving this problem that has been so vexing. Thank you for taking the time to help.


-Shikamaru

lejoe.thomas Sat, 11/08/2008 - 17:14
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Shikamaru


It's because you havent configured clock rate under the interfaces on the frame relay switch.


EXAMPLE

interface Serial0/0

description HQ

no ip address

encapsulation frame-relay

no fair-queue

frame-relay lmi-type cisco

frame-relay intf-type dce

frame-relay route 101 interface Serial1/0 103

frame-relay route 102 interface Serial1/1 104


add clock rate XXXXX to s0/0 s1/0 s1/1 on the frame relay switch


HTH

Lejoe


shikamarunara Sat, 11/08/2008 - 18:17
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Lejoe,

In this context, the "clock rate" syntax does not seem to do anything. In other words, when I add it, it's never reflected in the running config. I don't think the command is accepted because it's not relevant for this kind of set up.


-Shikamaru

lejoe.thomas Sat, 11/08/2008 - 18:32
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Shikamaru,


FR switch will act as DCE and it means we need to enable the clock rate with the appropriate speed.

It will show the clock rate in the running configuration.

shikamarunara Sat, 11/08/2008 - 18:36
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Lejoe,

I've applied it, it accepts the command, but oddly enough it doesn't show in the running config. Any ideas?


-Shikamaru

lejoe.thomas Sat, 11/08/2008 - 18:52
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Shikamaru


I do a run 2522 as Frame-relay switch and it does show clock rate in the running configuration. However, I dont know why it doesnt appear for you.


I'd just like to add small note on LMI and no keepalives you had in configuration. A frame relay DTE sends LMI status enquiry messages to the Frame-relay switch, which informs the router of the DLCIs associated with VCs and status of the VCs. And since you had no keep alives set, this is why it was probably showing them as inactive.


Anyways your problem is solved.


Lejoe

shikamarunara Sat, 11/08/2008 - 19:04
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I suspect that the clock rate isn't showing up because of an IOS nuance (I'm running the frame switch on a 2610). The keepalives clearly mandatory, and it explains why I was seeing the pvc status shift from active to inactive (which I didn't mention before), but I have no idea why other people would remove keepalives from their own configs for this kind of thing. Oh, well.


-Shikamaru

Richard Burts Sat, 11/08/2008 - 19:27
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Shikamaru


I am surprised that it is running ok without specifying clocking. But apparently it is. So I guess that there must be something in that router interface or that version of code that makes it work.


I am glad that my suggestion about keepalive turned out to be the key is solving the problem. I have seen routers running ok with no keepalive when the encapsulation was HDLC or PPP. But I do not understand why someone would suggest no keepalive when the encapsulation is Frame Relay.


Thank you for using the rating system to indicate that your problem was solved (and thanks for the rating). It makes the forum more useful when people can read about a problem and can see that a response did lead to a solution for the problem.


The forum is an excellent place to learn about Cisco networking. I encourage you to continue your participation in the forum.


HTH


Rick

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