Troubleshooting guide

Section 5, User Interface Guide - UIG-535, STS-1 Loopbacks
61186003L1-1D 5-99
CSU Loopback w/BERT
A CSU Loopback w/BERT enables the MX2820 STS-1 to test the local T1 loop to the CSU
using the standard QRSS pseudo-random bit sequence. When CSU Loopback w/BERT is
selected, the MX2820 STS-1 will initiate a CSU loopback towards the CSU attached to the
selected T1 line similar to the CSU Loopback test above. Six seconds after starting the CSU
loop-up pattern, the MX2820 STS-1 will cease sending the CSU loop-up pattern and begin
sending an unframed 511 pattern towards the CSU. If the CSU device responded to the CSU
loop-up pattern, the MX2820 STS-1 will check the incoming pattern for errors. Additional
menu items will appear to show the state of pattern synchronization, error count, and a clear
error count option (see Figure 5-69).
Selecting Data Mode will cease the transmission of the QRSS pattern and start transmission
of a loop-down pattern as previously described.
NOTE
Only one T1 port can engage a CSU Loopback, CSU Loopback w/
Bert, or a Line Bert. If a test of this type is already active at the
time a new test is selected, the former test will be terminated and
the latter test will be engaged.
Figure 5-69. Loopback Menu with BERT Selected
VT BERT
A VT BERT enables the MX2820 STS-1 to perform a “head-to-head” BERT test towards the
STS-1 network. Selecting VT BERT will replace all incoming T1/E1 traffic for the T1/E1
mapped to the selected VT with an unframed QRSS pattern towards the network. When VT
Shelf: 1 Slot: 4A ADTRAN MX2820 System 04/15/04 14:52
Unacknowledged Alarms: NONE TID: HTVLALEXD16
MX2820 Loopbacks
VT / Port Loopbacks VT / Port Loopbacks STS-1 Loopbacks
1 - (1 ) VT BERT 15 - (3 ) Data Mode 29 - STS-1 = Data Mode
2 - (5 ) Data Mode 16 - (7 ) Data Mode
3 - (9 ) Data Mode 17 - (11) Data Mode
4 - (13) Data Mode 18 - (15) Data Mode
5 - (17) Data Mode 19 - (19) Data Mode
6 - (21) Data Mode 20 - (23) Data Mode
7 - (25) Data Mode 21 - (27) Data Mode
8 - (2 ) Data Mode 22 - (4 ) Data Mode
9 - (6 ) Data Mode 23 - (8 ) Data Mode 30 - Reset ALL tests
10 - (10) Data Mode 24 - (12) Data Mode 31 - Insert One Bit Error
11 - (14) Data Mode 25 - (16) Data Mode 32 - Clear Error Count
12 - (18) Data Mode 26 - (20) Data Mode PATT = NO SYNC
13 - (22) Data Mode 27 - (24) Data Mode BERR = 0
14 - (26) Data Mode 28 - (28) Data Mode
Selection: '?' - System Help Screen