T1 to 56K CSU/DSU Back-to-Back

[sktech]

I have two 2500 routers that I need to setup in a lab envt. One of the routers has a T1 CSU/DSU module and the other has a 56K CSU/DSU module. I would like to know what type of cable I need to use to connect these two routers back-to-back?

Thanks in advnace,
sK

 

[jneiberger]

Unfortunately, you cannot connect these routers back-to-back with these interface types. The best you'll be able to do is run a crossover cable between the Ethernet interfaces.

 

[JOAMON]

Could you use a T1 x-over cable and set the T1 card for only 1 timeslot???

 

[sktech]

OK. How about T1 CSU/DSU module to another T1 CSU/DSU module? What type of cable can be used?

Thanks in advance,
sK

 

[jneiberger]

Nope, 56K DDS is incompatible with T1. It's not the same as a single DS0 channel.

 

[jneiberger]

If you have T1-to-T1 then you can use a T1 crossover cable, which is pins 1 and 2 crossed over to 4 and 5. (1-4, 2-5)

One side of the link will need to provide clocking and the other side will need to be set to derive its clock from the line (which is the default setting.)

 

[JOAMON]

T1 to T1 make a cable with the following pinout

1 to 4
2 to 5
4 to 1
5 to 2

 

[sktech]

Are the pinout 1-4,2-5,4-1,5-2 or
1-5,2-4,4-2, and 5-1 according to the following link:

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

 

[jneiberger]

You're looking at the loopback connector. Look at the crossover cable diagram: it is 1-4, 2-5.

 

[JOAMON]

Your diagram might be or adtran products....take a look at the following link.....

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

 

[jneiberger]

The diagram he linked to had the correct pinout for a crossover cable. He must have been looking at the diagram for the loopback connector on the same page, which is pinned 1-5, 2-4. That's definitely *not* want you want for a T1 crossover cable!

 

[JOAMON]

Take a closer look at his link.....the xover cable is pinned 1 to 5 and 2 to 4 instead of 1 to 4 and 2 to 5.

 

[jneiberger]

Oh, geez, you're right! I think I need more coffee or something.

It is interesting that they reverse the pins. I wonder if that's for polarity reasons?