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Cisco Bug: CSCut59888 - After MAC Flap, MAC is not relearned correctly on one of the VPC Peers.

Last Modified

Mar 09, 2017

Products (7)

  • Cisco Nexus 5000 Series Switches
  • Cisco Nexus 5548P Switch
  • Cisco Nexus 5596UP Switch
  • Cisco Nexus 6004 Switch
  • Cisco Nexus 6001 Switch
  • Cisco Nexus 5548UP Switch
  • Cisco Nexus 5596T Switch

Known Affected Releases

6.0(2)N2(4)

Description (partial)

Symptom:
After a short MAC-address flapping we can see on a VPC-Peer that 
one VPC peer has the MAC address pointing to a single source interface
Other VPC peer has the MAC address pointing to the different source interface

Example:

Switch_A# sh mac add dy vlan 10
Legend:
        * - primary entry, G - Gateway MAC, (R) - Routed MAC, O - Overlay MAC
        age - seconds since last seen,+ - primary entry using vPC Peer-Link
   VLAN     MAC Address      Type      age     Secure NTFY   Ports/SWID.SSID.LID
---------+-----------------+--------+---------+------+----+------------------
* 10       0000.0c07.ac00    dynamic   120        F    F  333.0.0


Switch_B# sh mac add dy vlan 10
Legend:
        * - primary entry, G - Gateway MAC, (R) - Routed MAC, O - Overlay MAC
        age - seconds since last seen,+ - primary entry using vPC Peer-Link
   VLAN     MAC Address      Type      age     Secure NTFY   Ports/SWID.SSID.LID
---------+-----------------+--------+---------+------+----+------------------
* 10       0000.0c07.ac00    dynamic   10         F    F  Po6

And traffic is sourced from source-mac  0000.0c07.ac00  only on Po6

Conditions:
2 Variations have been seen of the issue:
- MAC is wrong till MAX-age and corrects
- MAC is not cleared on MAX-age

This is only seen when only one leg of the VPC is receiving the traffic and one leg is not receiving *any* traffic from the affected source-mac address.
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Bug Details Include

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