Cabletron Systems Smart 04-0053-01 - Manual (Page 111)

SmartSwitch ATM User Guide 9-5
Troubleshooting Troubleshooting Congestion
*Use the show portconfig command to view bandwidth utilization
3. Has the congestion subsided?
• If yes, you are done.
• If no, continue.
4. Have you changed the EPD threshold ( set switchtrafficcongestion command)?
• If yes, replace it to the default setting. If congestion subsides, you are done.
• If no, continue.
5. Enter the show cacinfo and show portconfig commands 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.
6. Enter the show porttrafficcongestion command. Is the UBR queue MaxValue large?
• If no, go back to step 4.
• If yes, continue.
7. Reduce the UBR queue MaxValue by a small amount, then wait a few minutes.
8. 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.
9. Is the number of cells being dropped by all other ports decreasing somewhat?
• If no, go back to step 6.
• If yes, continue.
10. Enter the set caceqbwallocscheme command and set call admission control for this port to a more
conservative policy ( moderate or conservative ).
11. Go back to step 4 until all ports have been checked.
9.4.3 Port Congestion
1. Enter the show portstats command a few times, noting the value for cells dropped and unknown
VCs dropped. Is the number of cells dropped equal to the number of VCs dropped?
rt-VBR Bandwidth* utilization less than 20%: Min = 16, Max = 1024
rt-VBR Bandwidth* utilization greater than 20%: Min = 128, Max = 4096
Nrt-VBR Min = 256, Max = 4096
UBR Min = 256, Max = 8192
ABR Min = 256, Max = 8192
Table 9-1 Settings for Class of Service Queues (Continued)
Service Class Recommended Settings