Cabletron Systems SmartCell 6A000 Manuale Utente
5-4 SmartCell 6A000 User Guide
Troubleshooting Congestion
Troubleshooting
4.
Enter the
show cacstats
command for each port. Is the allocated bandwidth small and is the traffic
mostly UBR?
•
If no, go back to step 4 and check next port.
•
If yes, continue.
5.
Enter the
show porttrafficcongestion
command. Is the UBR queue Max threshold large?
•
If no, go back to step 4.
•
If yes, continue.
6.
Reduce the UBR queue Max threshold by a small amount, then wait a few minutes.
7.
Enter the
show portstats
command, and take the default of
all
. Is the number of cells dropped
increasing for this port, and quickly decreasing for all other ports?
•
If yes, proceed to the "Port Congestion" section.
•
If no, continue.
8.
Is the number of cells being dropped by all other ports decreasing somewhat?
•
If no, go back to step 7.
•
If yes, continue.
9.
Enter the
set cacparams
command and set call admission control for this port to a more
conservative policy (
moderate
or
conservative
).
10.
Go back to step 4 until all ports have been checked.
5.3.3
Port Congestion
1.
Enter the
show portstats
command a few times, noting the value for cells dropped and
unknown VCs dropped. Is the difference for cells dropped equal to the difference for VCs
dropped?
dropped?
•
If yes, the switch is improperly set up. Check the switch configuration.
•
If no, this indicates port congestion. Continue.
2.
Enter the
show cacstats
command for this port. Note the bandwidth allocated for each Class of
Service on this port.
3.
For each class of service, enter the
set porttrafficcongestion
command. Set the Max threshold
to the value recommended in the "Class of Service Queue Allocation Guidelines" section.
4.
Have you performed step 3 for every class of service for this port?
•
If no, go to step 3.
•
If yes, continue.
5.
Enter the
set cacparams
command for this port. Set call admission control for this port to a more
conservative policy (
moderate
or
conservative
).
6.
Check VC statistics for this port using either the
show pvc /d
or the
show svc /d
command,
whichever is appropriate.
7.
If the port belongs to the high virtual channel link (VCL), read the forward stats. If the port belongs
to the low VCL, read the backward stats. If the port belongs to both high and low VCLs, read both
stats.
to the low VCL, read the backward stats. If the port belongs to both high and low VCLs, read both
stats.