Low Throughput Problems - Alvarion BreezeACCESS VL System Manual

Appendix F - Troubleshooting
F.3

Low Throughput Problems

Problem and Indication
Low throughput is suspected
(Check the dominant Modulation
Level in Per rate Counters and
see expected throughput in the
"Expected Throughput" table
below)
Low throughput of
multicast/broadcast traffic
High retransmissions rate
Expected Throughput in Mbps, TCP Traffic @ 20 MHz Bandwidth,
Unit TCP Traffic
SU-3 Uplink
Downlink
Aggregate (Bi-directional)
SU-6 Uplink
Downlink
Aggregate (Bi-directional)
SU-54 Uplink
Downlink
Aggregate (Bi-directional)
* The throughput results are for net TCP traffic (excluding protocols overheads)
240
Possible Cause
Ethernet link problems
Wrong configuration of
Maximum Modulation
level
Non-optimal configuration
of Multicast Modulation
level
Interference problems
(retransmissions rate in
excess of 15%)
Burst Mode Enabled, Concatenation Enabled
1 2
1.9 1.9
2.9 2.9
3.3 3.3
3.8 3.8
4.8 5.6
5 6.7
4.7 6.7
4.8 7.1
4.8 7
Corrective Action
Verify proper settings of Ethernet
operation mode (actual Ethernet speed
of 100 Mbps).
Check Ethernet counters
Verify that Maximum Modulation level is not
set to a value that is not too low according to
the "Recommended Maximum Modulation
Level" table below.
A value that is too low (see the
"Recommended Maximum Modulation Level"
table below) may degrade throughput of
broadcast and multicast traffic.
Check for interference using the Spectrum
Analysis Mode. If necessary, change the
operating frequency of the AU.
Modulation Level
3 4 5
1.9 1.9 1.9
2.9 2.9 2.9
3.3 3.3 3.3
3.8 3.8 3.8
5.6 5.6 5.6
7 7.1 7.1
8.9 12.4 15.8
9.4 13.7 17.7
9.3 13.1 16.9
BreezeACCESS VL System Manual
6 7 8
1.9 1.9 1.9
2.9 2.9 2.9
3.3 3.3 3.3
3.8 3.8 3.8
5.6 5.6 5.6
7.2 7.2 7.2
21 25.1 26.4
24.7 28.9 30.1
22.8 29.4 32