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Cisco Bug: CSCul19094 - Non-ECN capable behavior enhancement

Last Modified

Feb 11, 2018

Products (6)

  • Cisco Nexus 3000 Series Switches
  • Cisco Nexus 3064 Switch
  • Cisco Nexus 3016 Switch
  • Cisco Nexus 3064-T Switch
  • Cisco Nexus 3048 Switch
  • Cisco Nexus 3132Q Switch

Known Affected Releases

6.0(2)U2(1)

Description (partial)

Problem:
When ECN and non-ECN capable traffic is present on the same egress queue, non-ECN-capable traffic gets dropped on exceeding the MAX threshold configured.
 
Requirement:
Under low congestion / queue build scenario, allow low rate non-ECN capable traffic to go through without drops, even if the ECN thresholds are exceeded. To keep the solution generic for any traffic stream with ECN bits set, avoid a stream type based classification.

Symptom:
ECT = 0 packets are dropped based on WRED thresholds applied on ECN enabled traffic classes.

Conditions:
Packets having ECT=0 and classfied to traffic classes where ECN is enabled.
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