[c-nsp] "All" vlan in show output

[Michael Kaegler]

On occasion, when I do a "show mac-address-table", I see some access 
ports (in single vlans) have addresses in vlan "All":


Vlan    Mac Address       Type        Ports
----    -----------       --------    -----
[...]
  201    0015.c565.1dee    DYNAMIC     Fa0/21
  All    0218.f32d.9f23    DYNAMIC     Fa0/43
  201    0016.365b.bc43    DYNAMIC     Fa0/24
[...]

I assume this means the switch is thinking the MAC is in every VLAN, 
but the port is in only one vlan (and has been since it linkup'd), 
and the port is set "switchport mode access".

I'm wondering if the user is somehow breaking out of his vlan... 
sending 802.1q frames into an untagged port may still get 
decapsulated later in the network, right? Would that have this effect?

I happen to be on the 2950 platform, 12.1(22)EA10.
TIA,
-porkchop

-- 
Michael "Porkchop" Kaegler, Sr. Network Analyst
(845) 575-3061 Marist College, Poughkeepsie, NY