Sniff VLAN ID

[spetrillo]

Is there a tool that would allow me to sniff the traffic coming in from my ISP, so I can determine if they are pushing a VLAN ID?

[bartjsmit]

Run the connection through a managed switch and connect a sniffer (tcpdump + promiscuous NIC) to the monitor port that mirrors either the connection from your ISP or the connection to the rest of your network.

Bart...