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Strange Problem with HSSI connection

I have a 7206 and a 3640 connected to each other via inverse-multiplexed T1s.

The IMUX are Digital Link DL-3800s. I have 4 point-to-point T1s for a total of 6.122Mbps. Each router has a HSSI module installed.

In one direction, moving data from the 7206 to the 3640, line performance is acceptable (although there are a small number of input errors in sh int) Howerver, in the reverse direction, moving data fromt he 3640 to the 7206, line performance is terrible, somewhere around 250Kbps or so. The interface counters on the HSSI interface of the 7206 show hundreds or thousands of CRC and input errors per second.

I have looked all over for a configuration/troubleshooting guide to HSSI interfaces, what I have found on CCO so far has not helped me much other than to list the possible configuration parameters, with no indication of when to use each one. According to the documentation for the IMUX the IMUX devices provide the clock to the DTE.


interface Hssi 4/0

bandwidth 6000

ip address

Interface Hssi 4/0

bandwidth 6000

ip address

Any insights or even suggestions of where to find a good HSSI primer would be greatly appreciated.


Re: Strange Problem with HSSI connection

The problem is the input/crc errors. Things to check/do:

-Try "show controllers serial" or "show service-module" to see if you have errors (check who is providing the clocking if errors).

-Do an extended ping across with data patterns 0x0000 (all zeros ping - line code mismatch), 0x1111 (all ones ping - line code mismatch), 0xffff (repeater power problems), 0x4040 (timing problems) and 0xaaaa. Do any fail?

-Is framing, line code etc matching the carrier's?

-Is the interface resetting constantly (if yes do a debug serial interface)?

-Perform loopback testing

-Have the carrier perform integrity tests on the line.

Hope it helps.