Cabletron Systems ZX-250 사용자 설명서

5-4   SmartCell ZX-250 User Guide

Troubleshooting Congestion

  Troubleshooting

5.4.1

Diagnosing Congestion

s•

Enter the 

 command, and take the default of (

).

¢•

If cells are not being dropped on all ports, proceed to the “Port Congestion” section.

••

If cells are being dropped on all ports, the indication is global congestion. Proceed to the “Global 
Congestion” section.

5.4.2

Global Congestion

s•

Is the total cell drop rate equal to the Unknown VC cell drop rate?

U

If yes, the switch is improperly set up. Check the switch configuration. 

U

If no, this indicates global congestion. Continue.

¢•

Set the 

 values to those recommended in the “QoS Queue Allocation 

Guidelines” section. Has the congestion subsided?

U

If yes, you are done.

U

If no, continue.

••

Have you changed the EPD threshold? 

U

If yes, replace it to the default setting. If congestion subsides, you are done.

U

If no, continue.

T•

Enter the 

 command for each port. Is the allocated bandwidth small and is the traffic 

mostly UBR?

U

If no, go back to step 4 and check next port.

U

If yes, continue.

Q•

Enter the 

 command. Is the UBR queue Max threshold large?

U

If no, go back to 4.

U

If yes, continue.

–•

Reduce the UBR queue Max threshold by a small amount, then wait a few minutes.

••

Enter the 

 command, and take the default of 

. Is the number of cells dropped 

increasing for this port, and quickly decreasing for all other ports?

U

If yes, proceed to the “Port Congestion” section.

U

If no, continue.

G•

Is the number of cells being dropped by all other ports decreasing somewhat?

U

If no, go back to step 6.

U

If yes, continue.

n•

Enter the 

command and set call admission control for this port to a more 

conservative policy (

 or 

).

s¥

Go back to step 4 until all ports have been checked.