Voice and VLAN's

Heres a scenario:

IP phone plugged into a switch (tagging its packets), PC daisy-chained to the IP phones going into the native VLAN.

So theoretically the PC and phone are isolated as they are in different vlans..........but as the port the PC is plugged into on the rear of the phone is a switchport, does that not mean that if the IP phone sent a broadcast it would reach the PC? Even though the PC is in a different VLAN?

Do you see what i am getting at? Doesnt that defeat the point of putting them in seperate VLAN's?

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Comments

masterk

Hang on, have i just figured this out.

Is it because the phone has switchports it makes it a sort of mini-switch, so then the phone (onboard switch) itself is configured so the port connected to the switch is in the phone vlan So the PC doesnt get those broadcasts?

chmorin

masterk wrote: »

Hang on, have i just figured this out.

Is it because the phone has switchports it makes it a sort of mini-switch, so then the phone (onboard switch) itself is configured so the port connected to the switch is in the phone vlan So the PC doesnt get those broadcasts?

Sort of. The best way to think of this 'mini trunk' is just to see the PC and the Phone on separate VLAN's. The phone is an intelligent trusted device by the switch, but the PC is not. Since they are logically isolated, a broadcast by the phone would only go out the SW port to other node's on the same VLAN. If the PC broadcasts, it will pass through the phone, allowing it to tag its traffic separately from the voice vlan, and off to the node's in its corresponding VLAN. The phone does not broadcast voice VLAN packets out its PC port, only the SW port.

Broadcasts do not arrive at node's in separate VLAN's, that is part of the point of configuring data and voice VLAN's.