06-21-2017 10:39 PM - edited 03-08-2019 11:03 AM
Dears,
Why would a switch report the same mac address of a host (IP Phone) on two VLANs on the same switchport?
switch#sh mac address-table inter Fa2/0/38
Mac Address Table
-------------------------------------------
Vlan Mac Address Type Ports
---- ----------- -------- -----
51 0014.****.**** STATIC Fa2/0/38
51 0023.****.**** STATIC Fa2/0/38
151 0014.****.**** DYNAMIC Fa2/0/38
Total Mac Addresses for this criterion: 3
switch#
vlan 51 is the data vlan and 151 is the voice vlan.
The port config is herebelow..
Current configuration : 138 bytes
!
interface FastEthernet2/0/38
switchport access vlan 51
switchport mode access
switchport voice vlan 151
spanning-tree portfast
end
Assistance appreciated.
Thanks.
06-21-2017 11:21 PM
Hi
is it a Cisco phone?
If so configure:
interface FastEthernet2/0/38
cdp enable
06-22-2017 12:13 AM
Thanks John, Ton...
This is quite clear... done exactly as advised.. and it still doesn't seem to behave...
06-21-2017 11:30 PM
Hi,
When the phone first connects to the switchport, it is not aware of the voice vlan and is placed in the data vlan. cdp/lldp then informs the phone of the voice vlan and the phone transitions to the voice vlan. For this reason, the mac address of the phone appears on the data vlan and the voice vlan.
Thanks
John
12-18-2020 10:43 AM
FWIW, johnd2310, posted the correct answer.
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