Configuring packet trimming

Only enable packet trimming if ECN is disabled on the respective queues. No automated check is available in the CLI to prevent this configuration.

Packet trimming is supported only on Layer 3 interfaces. Packet trimming configuration is global, and is therefore applicable to all Layer 3 interfaces, and applies to all traffic types and all drop probabilities.

To configure packet trimming:

  • Set the system-wide packet-trimming feature state to true (enable-packet-trimming true)
  • (7220 IXR-H6 only): Define one or more queues that are trimmable (trimmable-queues)
  • Define one or more DSCP values that are trimmable (trimmable-dscp)

  • For each of the trimmable DSCP values:

    • Define the remarked DSCP value (trimmed-dscp) for the trimmed packets. Trimmed packets are marked with this DSCP value regardless of any DSCP rewrite-rule policy defined on the interface.
    • Define the destination output queue (trimmed-packets-queue) for the trimmed packets.

Configure packet trimming

--{ candidate shared default  }--[  ]--
# info with-context qos packet-trimming trimmable-dscp 5
    qos {
        packet-trimming {
            enable-packet-trimming true
            trimmable-queues [   # 7220 IXR=H6 only
                unicast-3        # 7220 IXR=H6 only
            ]
            trimmable-dscp 5 {
                trimmed-dscp EF
                trimmed-packets-queue expedited
            }
            trimmable-dscp 6 {
                trimmed-dscp EF
                trimmed-packets-queue expedited
            }
        }
    }
}