Guest

Preview Tool

Cisco Bug: CSCup64606 - FCoE packet drops with Nexus N6004, N5696Q, and N56128P

Last Modified

Aug 14, 2018

Products (7)

  • Cisco Nexus 6000 Series Switches
  • Cisco Nexus 5596UP Switch
  • Cisco Nexus 5548P Switch
  • Cisco Nexus 6004 Switch
  • Cisco Nexus 6001 Switch
  • Cisco Nexus 5548UP Switch
  • Cisco Nexus 5596T Switch

Known Affected Releases

6.0(2)N2(3)

Description (partial)

Symptom:
Slow FC or FCOE Performance with Nexus N6004, N5696Q, or N56128P.Selective Retransmission Request (SRR) may be logged on host or storage.

Drops on the egress on a Nexus 5600/6000, for a no-drop class of traffic. Possible in both 10G & 40 G fabric modes, higher probability with 40G fabric mode. This can be verified by seeing counter increments in show hardware internal bigsur asic <global-asic-num> reg match .*wo_cr and via RX_FRM_DROP counter increments in show platform software qd info counters bm-fabric asic <global-asic-num>

The slowness observed in the application is due to the FCoE packet drops, which triggers retransmission from the application

Conditions:
On a Nexus 5600/600, when multiple ingress ports send data to one egress port for a no drop class of traffic and the egress buffer occupancy reaches the xoff threshold, this is indicated by observing the output of show hardware internal buffer info pkt-stats asic-num <global-asic-num> and verifying it to cross the xoff value for pool1 in Egress buffer allocation with the show platform software qd info command
Bug details contain sensitive information and therefore require a Cisco.com account to be viewed.

Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
  • Status
  • Severity
  • Known Fixed Releases
  • Related Community Discussions
  • Number of Related Support Cases
Bug information is viewable for customers and partners who have a service contract. Registered users can view up to 200 bugs per month without a service contract.