Tunnel Async Data
VER A 7/23/03
As an example, assume that async RS-232 devices are to be connected by leased line modems. Instead, the leased line modems are replaced with Cisco comm servers. Plug the RS-232 devices into async lines on the Cisco comm servers and connect the comm servers via an arbitrary topology IP network.  In [...]

If you know the MAC address use the following format:
sh cam 00-30-48-66-5A-D6
If you do not know the MAC address use the following to find it:
sh cam dynamic
If you know the VLAN and to make your search a little easier user the following:
sh cam dynamic 20
20 is the VLAN your machine is connected to.