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Communication Manager Maintenance-Object Repair Procedures
622 Maintenance Procedures for Avaya Communication Manager 3.0, Media Gateways and Servers
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 PKT-BUS (Packet Bus)
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.
Error
Type
Aux
Data
Description
769 35 Excessive LAPD retransmission requests
770 25 Uncorrectable ATM cell headers – threshold
If Then
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.
If Then
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.
If Then
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.