Troubleshooting of LAN/WAN Circuits

I have WAN/LAN circuits.

They are all Cisco. The core router (usually 7200 series, 7206) is interfacing with the carrier’s WAN cloud (T1, T3, DS-3, OC-3, etc) and connected to core switch (Cat 6500 series, 6509) from the other side. In some cases, the distribution layer switch is Cat 4506 or 3550 with VLAN implementations. The access switches are usually Cat 3550.

Once I telnet to core switch and logged in (which is preferred), how do I get to port(s) on the access switch(es) and shut down or unshut ports to certain hosts?

What are the Cisco commands/steps I have to use to get to the ports?

Your help is appreciated.

Thanks