Back to Back T1, help!

[mredel]

I have the following config setup:

Cisco 2620 running IOS 12.2(3)

Cisco 3640 running IOS 12.2(28)

The 2620 is connected to the 3640 via a T1 crossover cable. The 2620 has a WIC-1DSU-T1 module and the 3640 is using 1FE-CT1-CSU network module. I have configured each router as such:

3640 config:

controller t1 0/0

framing esf

linecode b8zs

clock source internal

channel-group 0 1-24 speed 64

interface serial 0/0:0

ip address 10.1.1.2 255.255.255.0

encapsulation hdlc

2620 config:

interface serial 0/0:0

ip address 10.1.1.1 255.255.255.0

encapsulation hdlc

service-module t1 framing esf

service-module t1 linecode b8zs

service-module t1 clock source line

service-module t1 timeslots all speed 64

For the life of me, I cannot get the T1 circuit to come up, both ends give exactly the same error when looking at the T1 controller status:

"Transmitter is sending loss of frame

Receiver has loss of signal"

Any suggestions?

[ggatten]

You are using a X-over cable, right? To my knowledge there's no way to set the "DTE/DCE" in software with these interfaces. You need a X-over cable to do this. This is the pinout I use:

1 -> 5

2 -> 4

4 -> 2

5 -> 1

HTH

Gary

[mredel]

Gary

Thanks. I am using the crossover cable you indicated.

[mhussein]

Hi,

I think you can use only 1 timeslot (DS0) when configuring a channelized T1 (3640) to a fractional T1/DSU (2620).

Try reconfiguring the interfaces to see if this makes a difference:

(3640)

channel-group 0 1 speed 64

(2620)

service-module t1 timeslots 1

Also, I think it is easier to debug ppp encapsulation instead of hdlc.

Regards,

Mustafa

[scottmac]

On one router, (config-Int)# add "intf-type DCE" and "clock rate <2000000>(-or whatever rate you want-).

The interface won't transmit unless you make the interface a DCE and give it a clock rate. Use the "?" to pull down the list of acceptable rates.

Also make sure your back-to-back cable is set so that the correct end connected to, and is labeled "DCE."

Back-to-back cables should have one end labeled "DCE" the other end is labeled "DTE."

Good Luck

Scott

[ggatten]

The DCE/DTE settings are for Serial IF's - Sync / Async. When Using back-to-back T1 connections, this is not necessary. Not sure what it would do, but it certainly isn't needed.

The configs look right. At this point I'd:

- Use a T1 loopback and test both CSU/DSU's and make sure they work correctly.

- Verify the X-over cable is OK. Use an Ohm meter or make a new one or something.

- Maybe try changing roles on the clock source? Doubt it will help, but you never know. Also maybe use "1-24" vs. the "all" keyword in the config. Again, doubtful that's the problem, but you never no.

On my desk I have (3) 2610's connected similar to your config, all with WIC-1DSU-T1. One "core" router with (2) of them - thus connecting to the other (2) "remote" routers. Same basic config as yours and I have no probs.

When you get this resolved please post the resolution. I'd be curious what it ends up being.

Gary