It is basically the end-point of tunnels. If you have tunnel interfaces with an IP address, a Layer 3 generic routing encapsulation (GRE) tunnel, or if you assign a MAC address or Digital Subscriber Line Access Multiplier (DSLAM) address, etc., to the tunnel -- it becomes a Layer 2 tunnel.
Hope it helps.
Layer 3 goes throught routers, layer 2 is confined to switches.
Last Wiki Answer Submitted: June 22, 2009 6:56 am by Sudhanshu810 pts.