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Cisco Bug: CSCta17209 - Catalyst 2k and 3k series switches sending MST BPDU's tagged incorrectly

Last Modified

Mar 01, 2018

Products (98)

  • Cisco Catalyst 3750 Series Switches
  • Cisco ME 3400EG-2CS-A Switch
  • Cisco Catalyst 3750V2-24PS Switch
  • Cisco Catalyst 3560E-48PD-SF Switch
  • Cisco ME 3400-24TS-A Switch
  • Cisco Catalyst 3560-12PC-S Compact Switch
  • Cisco Catalyst 3560E-24TD-S Switch
  • Cisco Catalyst 2960G-24TC-L Switch
  • Cisco Catalyst 3560E-12D-E Switch
  • Cisco Catalyst 2960-48TT-S Switch
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Known Affected Releases

12.2(46)SE 12.2(50)SE 12.2(50)SE1 12.2(50)SE2 12.2(50)SE3

Description (partial)


Ports will be put into blocking state due to P2P dispute when "vlan dot1q tag native" is configured.  This happens because Catalyst 2k and 3k series switches are incorrectly sending MST BPDU's as tagged in the native VLAN.  Catalyst 7600 and 6500 series switches no longer accept tagged MST BPDU's due to changes in the code.


All of the following must be true:

- The switch is a Catalyst 2960/2970/3560/3750/3750ME or ME2400/ME3400.
- The command "vlan dot1q tag native" appears in the global configuration.
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