You have some cdp/lldp-capable switches serving your servers, and you want to get information which server using which port in easy and auto-discovering way, just like that:
Switch#show cdp nei Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone Device ID Local Intrfce Holdtme Capability Platform Port ID vc.eq.domain. Fas 0/21 119 H i386 em1 pf2.domain. Fas 0/8 165 H i386 fxp0 pf2.domain. Fas 0/5 165 H i386 xl0
Switch>show lldp nei Capability codes: (R) Router, (B) Bridge, (T) Telephone, (C) DOCSIS Cable Device (W) WLAN Access Point, (P) Repeater, (S) Station, (O) Other Device ID Local Intf Hold-time Capability Port ID chumadan Fa0/22 180 S vlan900
Well, CDPD is done right for that.
This version considered unstable because CYGWIN builds is most possibly broken here. On the other hand, there is a native Windows version cdpd.exe, based on code provided by Steinar H. Gunderson. Requires WinPcap