Zhone Technologies 900 - Manual (Page 78)

2-12 IMACS System Release 5.1.6 Data Cards
Model No. Running Head SRU Card User Screens and Settings SRU Card
LB DET
The Loopback Detection setting determines how the card will respond to latching and
non-latching loopback commands from remote equipment. The SRU reacts only to the inband
DDS-format loopback commands for OCU Loop, CSU Loop, and DSU Loop. The Loopback
Detection setting does not affect local loopback commands from the local control terminal.
The on option causes the card to monitor ports for DDS format loopback commands from the
remote equipment. If the card detects a loopback command, it loops the data back until the
remote equipment sends a stop loopback command. The w/to (with time-out) option is the
same as the on option, except that after ten minutes the SRU card automatically releases
loopbacks commanded by the remote equipment. The off option causes the SRU card to
ignore all remote loopback commands. This field will show n/a if adpcm or hlink are chosen
for the FRAME parameter.
DL OPT
Delay Optimization decreases the end-to-end delay time for applications that require lower
delay time. The options are off and on.
The cost of using Delay Optimization is a decrease in total bandwidth for the card by a factor
of 1.5. For example, a customer that has 10 ports using the sync Interface will have a 115.2
kbps maximum bandwidth. If delay optimization is used on all 10 ports, the maximum
bandwidth will be 76.8 kbps.
ADPCM
If adpcm is chosen as the Frame parameter, this field allows you to select the ADPCM card
to direct this traffic. The ADPCM card options are P1, P2 and P3 (the resource card slot
designations stamped on the chassis). If any other option is selected, this field will show n/a.
MAJ EC
The Majority-Vote Error Correction parameter is available for ports using DS0A framing at
speeds of 9.6 kbps and lower. This option selection is a two-step process. The initial options
are off and on. If the on option is chosen, a new set of options will appear at the bottom of the
screen.
The new options are used to select the error threshold, above which the card will generate an
alarm. The choices are none, 10e-3, 10e-4, 10e-5, 10e-6, and 10e-7. While the majority vote
algorithm is capable of correcting error rates in excess of 10e-3, the Excessive Error Rate
alarm gives system administrators advanced notice of problems before users detect them.
Table 2-4 shows the bit error rates for majority-vote error correction.