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Prashanth Kumar

Dropping scavenger packets on ASR 9000 during congestion

I am trying to find a solution using modular QOS when there is congestion in circuit we drop packets with WRED which are marked with a DSCP value of say AF21. I can drop those traffic completely in case of congestion.  I was thinking to allocate 100% bandiwth to rest of the traffic. Will this work or is thre any other elegant solution.

Joseph W. Doherty
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Generally (W)RED is only suitable for rate adaptive traffic, and if the traffic is rate adaptive, you usually don't want to drop all such traffic's packets.

WRED can be used to create drop tiers for rate non-adaptive traffic.

On sub Ethernet bandwidth links, with few flows, I've found drop management better with FQ per flow queue depths.

RED works better with Ethernet or better bandwidths with many flows, especially when FQ not avaible.

Depending on platform, FRED or DBL might be more elegant options.

Much depends on your service requirements.