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random-detect dscp-based thresholds explanation

Can someone explain why the default min thresholds for dscp are larger for the higher probability AF class than the lower probability classes?

for example:

http://www.cisco.com/en/US/docs/ios/qos/command/reference/qos_q1.html#wp1052917

dscp 10 has min of 24

dscp 12 has min of 28

thanks in advance

1 REPLY
Cisco Employee

Re: random-detect dscp-based thresholds explanation

Hello,

Indeed, looks like this is a mistake in this table.

Should be another way around - af11(dscp10) - min thr 32, af12(dscp12) - min thr 28, af13(dscp14) - min thr 24.

Real values could be checked via "show policy-map int" on CLI, like shown at the following example link:

DSCP Value Configuration Verification: Example

http://www.cisco.com/en/US/docs/ios/qos/configuration/guide/config_wred_ps6441_TSD_Products_Configuration_Guide_Chapter.html#wp1002513

Router# show policy interface Serial6/3 
 Serial6/3 

  Service-policy output: test

    Class-map: c1 (match-any)
      0 packets, 0 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match: protocol ip
        0 packets, 0 bytes
        5 minute rate 0 bps
      Weighted Fair Queueing
        Output Queue: Conversation 265 
        Bandwidth 20 (%)
        Bandwidth 308 (kbps)
        (pkts matched/bytes matched) 0/0
        (depth/total drops/no-buffer drops) 0/0/0
         exponential weight: 9
         mean queue depth: 0

dscp     Transmitted       Random drop      Tail drop    Minimum Maximum  Mark
          pkts/bytes        pkts/bytes       pkts/bytes    thresh  thresh  prob
af11          0/0               0/0              0/0           32      40  1/10
af12          0/0               0/0              0/0           28      40  1/10
af13          0/0               0/0              0/0           24      40  1/10
af21          0/0               0/0              0/0           32      40  1/10
af22          0/0               0/0              0/0           28      40  1/10
af23          0/0               0/0              0/0           24      40  1/10
af31          0/0               0/0              0/0           32      40  1/10
...

Thanks,
Sergey

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