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3620, NM-2FE2W, WIC-2T Compatibility

Is anyone running a 3620 router, with an NM-2FE2W carrier module, with a WIC-2T using Frame-Relay?

I have been asked to look at a possible hardware issue with these components, and have seen one of the serial ports up, and the other bouncing.

The circuits have been tested and are fine.

I have put the router in a lab using HDLC encapsulation, and can get both serial ports to work. I have even put a WIC-1T in the spare slot to ensure that the WIC-2T is not faulty. All three interfaces work.

When I configure the router for Frame-Relay encapsulation, the WIC-1T interface is fine and traffic passes over the link.

The WIC-2T interface comes up when enabled, but drops after 30 seconds (3 keepalives).

By debugging the Frame-Relay LMI I see that the router is not receiving LMI status messages from the FR switch. The FR switch (another 3620) is sending the messages, and is receiving enquiries from the DTE.

eg (taken before the DTE drops the link)

00:16:14: Serial0/0(out): StEnq, myseq 3, yourseen 0, DTE up

00:16:14: datagramstart = 0x2B014D4, datagramsize = 13

00:16:14: FR encap = 0xFCF10309

00:16:14: 00 75 01 01 00 03 02 03 00

00:16:14:

00:16:24: Serial0/0(out): StEnq, myseq 4, yourseen 0, DTE up

00:16:24: datagramstart = 0x2B01614, datagramsize = 13

00:16:24: FR encap = 0xFCF10309

00:16:24: 00 75 01 01 00 03 02 04 00

00:16:24:

On the WIC-1T interface the same debug shows the correct sequence...

00:07:22: Serial0/2(out): StEnq, myseq 43, yourseen 42, DTE up

00:07:22: datagramstart = 0x2D092B4, datagramsize = 13

00:07:22: FR encap = 0xFCF10309

00:07:22: 00 75 01 01 01 03 02 2B 2A

00:07:22:

The config is very straight forward ...

DTE config excerpt ...

interface Serial0/0

no ip address

encapsulation frame-relay

no fair-queue

clockrate 2000000

!

interface Serial0/0.100 point-to-point

ip address 172.21.22.2 255.255.255.252

frame-relay interface-dlci 100

!

interface Serial0/0.101 point-to-point

ip address 172.21.22.106 255.255.255.252

frame-relay interface-dlci 101

DCE config excerpt ...

frame-relay switching

!

interface Serial0/1

no ip address

encapsulation frame-relay

clockrate 2000000

frame-relay intf-type dce

!

interface Serial0/1.100 point-to-point

ip address 172.21.22.1 255.255.255.252

frame-relay interface-dlci 100

!

interface Serial0/1.101 point-to-point

ip address 172.21.22.105 255.255.255.252

frame-relay interface-dlci 101

The LMI type is cisco (I have tried ansi and q933a) and the FR encap is defaulted to cisco (I have tried IETF).

I have tried a number of different IOS versions and feature sets (12.1T, 12.2, 12.2T / IP and IP plus)

I have completely swapped all the hardware for new equipment, and have used from 32MB DRAM to 64MB DRAM, and from 8MB Flash to 24MB Flash dependent on IOS version.

Has anyone else experienced this, or have any advice?

Why should this work for HDLC, but not FR?

2 REPLIES
Cisco Employee

Re: 3620, NM-2FE2W, WIC-2T Compatibility

From the description you have given this is NOT a hardware issue.

Try dropping the clockrate on the dce to 64k for a test, I know it should support higher speeds but I suspect this is part of the problem if it work we can then work out why the higher speeds didnt work

In the 2nd NM wic slot do you have any WIC's installed ??

New Member

Re: 3620, NM-2FE2W, WIC-2T Compatibility

This turned out to be a combination of faulty WIC-2Ts, and back-to-back cables.

The SS DCE cable appears to have had some partially broken connections that worked sometimes, and then with some movement, stopped.

After building a new test rig, and systematically going through the parts supplied it became clear that there is no compatibility issue.

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