Symptom

STP BPDU are not transited across the fabric, which can lead to Layer 2 instability. You can check for tx, but not rx bpdu, with the following command: show spanning internal info all | egrep 'bpdu_in|bpdu_out|Eth1'

Conditions

3.2 software and Gen1 leaf switch This affects IEEE STP BPDUs such 802.1d, Rapid STP 802.1w, MST 802.1s. This does not affect Cisco PVST+ or rapid PVST+ which sends BPDUs with a destination MAC of 01:00:0c:cc:cc:cd

Workaround

Use Cisco PVST+ or rapid PVST+, which sends BPDUs with a destination MAC of 01:00:0c:cc:cc:cd. or Upgrade to a release with the fix.

Further Problem Description