Fixing Leased-Line Problems
The most common problem with leased lines is poor performance. In most situations, you
need to work with the telephone company to fix the problem.
Table 21-6 Common Leased-Line Problems
Symptom |
Problem |
Solution |
|---|
The link does
not start. |
CSU biopolar violations (CSU BPVs) can be the cause. One end of the
link is set up for AMI lines. The other end is set up
for ESF bit–8 zero substitute (B8Zs). |
If you are in the United States or Canada,
you can directly fix this problem from the menu of the CSU/DSU. Check the
CSU/DSU manufacturer's documentation for details. In other locales, the provider might be responsible for
fixing CSU BPVs. |
The link has poor performance. |
The pppd debug output shows CRC errors when sustained
traffic is on the link. Your line might have a clocking problem, caused by
misconfigurations between the telephone company and your network. |
Contact the telephone company to ensure that
“loop clocking” is in use. On some unstructured leased lines, you might have to
supply clocking. North American users should use loop clocking. |