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

or that:

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.

Stable versions:

Unstable (yet) version:

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