Avaya CS 1000 Maintenance

CRC-4 word errors
When operating in the CRC-4 multiframe format (CRC), frames are bundled into groups of 16.
This format includes a specific multiframe alignment pattern in bit 0 of every even frame's
timeslot 0 (00101
1XX).
Each odd frame timeslot 0 includes a CRC-4 cyclic redundancy checksum of the previous 8
frames (sub-multiframe). This transmitted checksum is compared against a calculated
checksum at the receiver. If the two checksums do not match, a CRC-4 word error is
indicated.
Group I error rates are processed on the PRI card based on software downloadable parameters
N1 and N2 (for each BPV, CRC, and FBER). The values for N1 are scaled on the card as
follows:
• BPV = N1•16
• CRC = N1•4
• FBER = N1•1
N2 values are not scaled. These parameters can be set in LD 73 on a per-card basis, or they
can be left at their default values.
Parameters N1 and N2 provide for the following error rate thresholds reported to the system:
• Severely errored second: When the number of occurrences of the error exceeds the value
of N1 in the previous second. This error is reported and counted (LCNT), but no action is
taken by the system.
• Unavailable condition: This is reported when 10 severely errored seconds are received
in 10 consecutive seconds. This is equivalent to an error rate worse than 10
-3
with the
default value. When this condition is reached, the 2.0 Mb PRI is put into an out-of-service
condition until the Group I OOS guard timer expires and the error condition has ceased
or improved.
• No new call condition: When the number of occurrences of the error exceeds the value
of (10 x N2) in the previous minute. This corresponds to an error rate of 10
-3
to 10
-5
using
the default N2 value. When this condition is reported, the system records the error (LCNT)
and places the PRI card into a "no new call" condition, with all idle channels set to MbSY.
The card automatically returns to normal state when the condition improves after the
Group I NNC guard timer expires.
• Maintenance condition: This condition exists when the number of occurrences of the error
exceeds the value of N2 in the previous minute. This corresponds to an error rate between
10
-5
and 10
-6
based on the N2 default values. When this condition is reported, the system
records the error (LCNT) and places the 2.0 Mb PRI card into a maintenance alarm state.
This state has no effect on call processing, it simply indicates line degradation. The card
automatically returns to normal state when the condition improves after the Group I
MAINT guard timer expires.
Monitor system PRI operation
ISDN Primary Rate Interface Maintenance November 2011 151

Avaya CS 1000 Specifications

General

Brand	Avaya
Model	CS 1000
Category	Server
Language	English