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3 port congestion, Port congestion -4 – Cabletron Systems SmartCell 6A000 User Manual

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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?

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.