Configuring RED

Each line module supports a default drop profile and 15 configurable drop profiles. You can configure the default drop profile on all E Series line modules except for the ES2 10G LM.

To configure RED:

  1. Create a drop profile and enter Drop Profile Configuration mode.
    host1(config)#drop-profile internetDropProfile host1(config-drop-profile)#

    You can configure up to 16 drop profiles.

  2. Set the average-length exponent, which specifies the exponent used to weight the average queue length over time, controlling WRED responsiveness.
    host1(config-drop-profile)#average-length-exponent 9
    • Specifying an average-length exponent enables the RED average queue length computation.
    • A higher value smoothens out the average and slows WRED reaction to congestion and decongestion, accommodating short bursts without dropping. Too large a value can smooth the average to the point that WRED does not react at all.
    • A lower value speeds up WRED reaction. Too low a value can cause overreaction to short bursts, dropping packets unnecessarily.
  3. (Optional) Set the minimum and maximum threshold for committed traffic.
    host1(config-drop-profile)#committed-threshold percent 30 90 4
  4. (Optional) Set the minimum and maximum threshold for conformed traffic.
    host1(config-drop-profile)#conformed-threshold percent 25 90 5
  5. (Optional) Set the minimum and maximum threshold for exceeded traffic.
    host1(config-drop-profile)#exceeded-threshold percent 20 90 6

    The thresholds specify a linear relationship between average queue length and drop probability.

    You can express thresholds as either percentages of maximum queue size by including the keyword percent, or as absolute byte values by omitting the keyword.

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