Avaya S8700 Maintenance Manual page 961

ATM-NTWK (ATM Network Error)
c. Error Type 301 — indicates that there is a system wide impaired path
network problem.
d. Error Type 769 — ATM CLP (Cell Loss Priority) Bit Errors
The ATM cell header has a bit called the cell loss priority (CLP) bit. The bit
indicates one of two states: the cell is eligible for discarding, or it is not. In
an ATM configuration, every cell is transmitted into the ATM network with
the CLP bit set to 0 indicating that these cells are NOT eligible for
discarding. Should the system ever receive a cell from the ATM network
with the CLP bit set to 1 (discard eligible), an entity in the ATM network
modified the bit during transit. Generally, an ATM network switch sets the
CLP bit to 1 (discard eligible) only if the cell fails to conform to the cell rate
specified in the traffic contract for the VC. However, MultiVantage cell
emissions conform with the VC traffic contract. Therefore, the presence of
a non-conforming cell implies that something else in the ATM network
switch is setting the CLP bit in some cells, the ATM switch can also be
policing out (discarding) cells which do not conform to the traffic contract.
This error can occur together with other errors such as:
These errors affect SVCs with Variable Bit Rate (VBRnt) traffic contracts.
VBR SVCs transport system links such as EAL, PACL, and PRI links.
Again, this indicates problems with cell transmissions in the ATM network.
If cell discard is happening generically in the ATM network, other
symptoms can affect the Constant Bit Rate (CBR) SVCs including audible
artifacts in talk paths, failure of modems over voice lines, and "Cell
Underruns" - see note (f).
e. Error Type 1025 — ATM Congestion Bit Errors
The ATM cell header has a bit called the congestion bit. In MultiVantage
ATM, every cell is transmitted into the ATM network with the congestion bit
set to 0 (congestion not experienced). Should the system ever receive a
cell from the ATM network with the congestion bit set to 1 (congestion
experienced), an entity in the ATM network modified the bit during transit.
It simply indicates that the ATM network is experiencing heavy traffic.
During periods of congestion, the ATM network can choose to discard cells
even though those cells conform to their traffic contracts. Should the ATM
network discard cells, errors such as the following can occur:
555-233-143
NOTE:
Under certain circumstances network errors can be against the ATM
EI board.
"Excessive AAL-5 CRC errors" or
"Excessive LAP-D retransmissions"
"Excessive AAL-5 CRC errors"
"Excessive LAP-D retransmissions".
Issue 1 May 2002 8-239