The Cisco 2524-2525 can be used in back-to-back configurations with the T1 CSU/DSU and the four-wire 56k CSU/DSU using a cross-over cable between the CSU/DSUs. The two-Wire CSU/DSU cannot be configured for back-to-back operation in this manner. Back-to-back configuration of the 4-wire CSU/DSU has the following restrictions:
You cannot use a clock rate of auto on either side of the back-to-back setup
You cannot use a clock rate of 64 .
You cannot use switched-56 operation .
For more information on document conventions, see the Cisco Technical Tips Conventions.
There are no specific prerequisites for this document.
The T1 CSU/DSU has a different pinout than the four-wire 56k CSU/DSU. The connector for the T1 CSU/DSU is an RJ-48C. The connector for the four-wire 56k CSU/DSU is an RJ-48S. Both connectors are compatible with RJ-45 plugs.
|From RJ 48C Pin||To RJ-48C Pin|
|From RJ 48S Pin||To RJ-48S Pin|
Tip: You can actually use a Cisco rolled RJ-45 cable (CAB-500RJ=) as a four-wire 56k cross-over cable. Even though the polarity is wrong, the bi-polar signal will be interpreted correctly by the CSU/DSU.
Tip: Make sure you count the RJ-45 pins as shown in the illustration below:
Set one CSU/DSU to clock source internal, and the other CSU/DSU to clock source line. On the CSU/DSU with internal clock, the clock rate must not be auto. Both CSU/DSUs must be set for service-module 56k network-type dds.
The Cisco Support Community is a forum for you to ask and answer questions, share suggestions, and collaborate with your peers.
Refer to Cisco Technical Tips Conventions for information on conventions used in this document.