Connecting 2 Cisco 1720's Back to back???? 1

[DOMIN80R]

OK, Im new here but I have read thru these forums and found that the members of this community are pretty well informed and helpful to say the least.

This is what I have

2 Cisco 1720 Routers with T1 WAN CSU/DSU cards.

They are configured to use a ptp t1 line as of now. I want to used these to do some testing and learning but I want to use an eithernet patch cable connected to the WAN cards.

1st. Is this possible? I was told it was.
2nd. What would I use is it in possible? Strait thru, crossover, or custome pinout?
3rd. Timing. Do I need to enable internal timing?


Thanks for any help in advance.

 

[MartinR82]

Not quite sure what you are trying to acheive here...

you have both connected together using a serial connection and now want to connect the LANs together also?

If that is the case then you need to use a straight thru

 

[JOAMON]

Pretty simple to make a custom back to back cable.


Pinout is:

1 --- 5
2 --- 4
4 --- 2
5 --- 1

Must enable internal clocking on one serial interface

 

[DOMIN80R]

No, I wanted to use an ethernet cable to connect the 2 T1 CSU/DSU cards and use it for testing and configured properly before implementation. I found what I was looking for on another site.

What was needed to connect 2 T1 CSU/DSU WAN cards is
and ethernet cable with these pins crossed

1 -- 4
2 -- 5

Works great then with out the need to a live T1 circut for testing

 

[JOAMON]

I've never tried that pinout......always used the one I posted without problem. T1 ciruits are a four wire connection. Take a look at the following link:

http://www2.adtran.com/support/technotes/t1ddsadptxvr/

 

[saw164]

since T1 transmission use pairs 1,2,4,5 on an ethernet cable, you need to cross them to have two T1 interfaces talking,we use that pinout all the time for connecting T1's out of our microwave system!

 

[DOMIN80R]

YEa, Saw 1,2,4,5 is the key here. I have not tried the way JOAMON has but maybe one day. Not sure if it will. About 3 other sites have listed the way I posted

 

[DOMIN80R]

JOAMON

I dont mean to discredit you. Im not sure about adtrain but what I was looking for the the cable for the cisco T1 CSU/DSU Modules. Maybe the adtrain CSU/DSU's are a bit diffrent and or both configurations will work depending of this CSU/DSU is a stand alone or internal unit.

Thanks for the help everyone

 

[JOAMON]

T1 circuits are 4 wire connections. You gotta have four wires on each side or data may not flow correctly. I used this pinout on two cisco 2611 routers with wic-1dsu-t1 interface cards. I was able to pass data in both directions. I cannot see how two wires will work correctly but if it does then use it. The addtran site was just the first link I found. Take a look at the link direct from the horses mouth:

http://www.cisco.com/en/US/products/hw/routers/ps233/products_tech_note09186a00800a3f09.shtml

 

[DOMIN80R]

I guess you mis read my post.

I only listed the crossed pairs: meaning
cross 1 to 4 and 2 to 5 with the other pairs intact

 

[JOAMON]

I stand corrected...the addtran is wrong....cant see straight today.....sorry

The Cisco sight has the correct pinout though.

1 --- 4
2 --- 5
4 --- 1
5 --- 2

 

[JOAMON]

Pin 1 and 2 on each side are for receive and pin 4 and 5 on each side are transmit.

T1 Signaling

1 RX (input) 4 TX (output)

2 RX (input) 5 TX (output)

4 TX (output) 1 RX (input)

5 TX (output) 2 RX (input)




Any pin not referenced on a connector is not used.

 

[JOAMON]

Sorry bout posting the ADDTRAN link but at first glance it looked like the the pinout I used.