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Cisco Bug: CSCuo68435 - On N6k programming of updated Fabricpath FWD entries to hardware delayed

Last Modified

Jan 30, 2017

Products (7)

  • Cisco Nexus 6000 Series Switches
  • Cisco Nexus 5548P Switch
  • Cisco Nexus 5596UP Switch
  • Cisco Nexus 6004 Switch
  • Cisco Nexus 6001 Switch
  • Cisco Nexus 5672UP Switch
  • Cisco Nexus 5548UP Switch

Known Affected Releases

6.0(2)N2(3) 7.0(1)N1(1) 7.1(0)N1(0.197)

Description (partial)

Symptom:
On N6k devices when Fabricpath topology is updated, programming of the updated forwarding entries to hardware is being delayed by 30-60 seconds. As a result some traffic flows might experience drops during that time. The issue recovers by itself after the period of 30-60 seconds.

Executing "show platform info pif all | inc drop", "clear mac address-table dynamic" or "show running-config" commands during the issue on the N6k device with staled Fabricpath forwarding entries in hardware recovers the setup from the issue immediately.

Conditions:
The issue might be seen on N6k Fabricpath spine devices on Fabricpath topology change event. This is seen in case there is N5k VPC+ setup connected to the N6k Fabricpath setup, and the VPC peer-link on the N5k VPC+ setup becomes disabled. The traffic which was previously sent by N6k FP switch towards N5k Secondary VPC+ switch should be shifted to the N5k Primary VPC+ switch, but this transition is delayed by 30-60 seconds.

The problem is seen when there are active VPC orphan ports on the N5k Secondary VPC+ switch. If the orphan port is manually disabled by "shutdown" command, or "vpc orphan-port suspend" command is used - the issue disappears.
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