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Cisco Bug: CSCul25514 - VPC port in Root Blocking state

Last Modified

Feb 14, 2018

Products (1)

  • Cisco Nexus 7000 Series Switches

Known Affected Releases

6.2(5.45)S3 6.2(5.49)S0

Description (partial)

Spanning tree marks a vPC port as "Root BLK" if it receives a superior BPDU

# sh span int po1

Vlan             Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
VLAN20           Root BLK 1         128.4096 (vPC) P2p

This issue occurs on a Nexus 7000 running vPC
It has been seen after upgrade to 6.2.
Occurs when the N7k vPC pair loses root bridge election off a vPC
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