Avaya 03-300430 User Manual

g. Error Type 769, 770: the ATM switch is requesting too many LAPD retransmissions 

(off-board ATM cell corruption errors).

1. Check the connections between the fiber cable, the ATM-TRK circuit pack, and the ATM 

switch.

2. See 

on page 1790 for test and corrective procedures.

3. Determine what type of fiber is installed between the ATM-TRK circuit pack and the ATM 

switch.

4. Perform ATM loopback tests on the near-end ATM-TRK circuit pack and on the far-end 

circuit pack or ATM switch.

5. Check capacity and peak bandwidth consumption for the ATM span.

769

35

Excessive LAPD retransmission requests

770

25

Uncorrectable ATM cell headers – threshold

There is multimode fiber

Check the length of the fiber.  If the cable is 

longer than 2 km, it may be causing errors.

There is single-mode fiber or the length of 

the multimode fiber is less than 2 km

The source of the errors can lie in the ATM 

facility, the ATM-TRK circuit pack, or the far-end 

circuit pack.

The ATM-TRK circuit pack fails the 

loopback test.

The problem is in the ATM-TRK circuit pack.  

Replace the circuit pack.

The far-end circuit pack or ATM switch 

fails the loopback test.

The problem is in the far-end circuit pack or ATM 

switch.  Consult the circuit-pack or ATM switch 

documentation for advice.

The equipment at each end of the ATM 

span passes the loopback test

The problem is somewhere in the ATM span.  Lack 

of bandwidth can be forcing an intermediate ATM 

switch to drop cells.

The capacity of the span is inadequate, or 

bandwidth consumption is too high.

Reduce traffic on the system to ensure that it is 

using no more that its subscribed bandwidth.