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Cisco Bug: CSCus15722 - 3905 Second Port Status TLV

Last Modified

Feb 06, 2017

Products (1)

  • Cisco Unified IP Phone 6900 Series

Known Affected Releases


Description (partial)

The security policy violation occurs, if the host is being connected via Cisco IP Phone and then reconnecting directly to another port on the same switch.
The MAC address of this host is not flushed from the table and is still mapped to be learned via previous access port (where IP Phone attached), so port-security policy violation occurs.

It happens because 3905 phone is not changing Second Port Status TLV

For CP-3905:

Capabilities: 0x00000290
VoIP Phone
CVTA Phone Port <== !!!

No second port status TLV (value is 0x001c), because bit 10 is unset


For CP-7861:

Capabilities: 0x00000490
VoIP Phone
Two-port MAC Relay <== !!!

Second Port Status TLV (0x001c):

when host is attached and phone's port is UP:
00 01 82 (UP, full/duplex, 100 Mb/s)

when host is detached and phone's port is DOWN:
00 02 00 (DOWN)

Port security enabled switch and the 3905 phone with PC connected to its internal switch
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