CDP for your computer

I recently had a room that was in the office that was remodeled into a sea of cubicles with all new wiring. The maintenance crew built the cubicles and ran all of the CAT5 drops to each desk. Two different groups were being merged into the same room, yet needed to keep their original VLAN so they could retain their access into the secure areas of the network.


When I got the seating chart I asked the maintenance guys for the wiring diagram and what switch port each desk connected to. They had nothing for me so I headed to the desks to get it figured out. My coworker educated me about a piece of software called CDPR. With CDPR I was able to connect to the jack at the desk and find out what port on the Cisco switch I was connected to.

You place this software on your computer, go to that directory from a command prompt and execute the file. If you have multiple NIC’s it will ask you what NIC to use. After you select your NIC, you simply have to wait until it receives a Cisco Discovery Protocol (CDP) packet from the switch and then it will tell you the switch name and the port. When we did this room, we shortened the CDP timers so it would advertise more often. Below is an example of what it looks like to run it and select your NIC.

C:\>cdpr
cdpr – Cisco Discovery Protocol Reporter Version 1.0.7
Copyright (c) 2002 – MonkeyMental.com

1. \Device\NPF_{FCFF8C2B-958F-4080-A1B9-0D464447009F} (Intel(R) 82577LM Gigabit
Network Connection)
2. \Device\NPF_{D27E2C86-F323-4D6D-8451-1AA70F0F6064} (Microsoft)
Enter the interface number (1-2):

You can get your copy of CDPR follow the link to MonkeyMental.com.

I thought this was a really slick tool and was very happy my coworker let me know about it.

Have you ever used this before or do you have a tool similar to this? If so, let us know!!

If you enjoyed this article, please consider sharing it!

This entry was posted in Cabling, General Cisco, Switching and tagged , by Scape. Bookmark the permalink.

About Scape

Over 10 Years in the networking field. Have worked in the Service provider and Enterprise environments. I have worked with Cisco, Foundry/Brocade, F5, Riverbed, Scientific Atlanta, Routers, Switches, Firewalls, Load Balancers, WAN Accelerators, DWDM, SONET, Multicast etc...

3 thoughts on “CDP for your computer

  1. Somebody had stated they didn’t see any output, so here is some output. The first one is connected to a Cisco IP Phone, the second is directly into a Cisco Switch.

    C:\>cdpr
    cdpr – Cisco Discovery Protocol Reporter Version 1.0.7
    Copyright (c) 2002 – MonkeyMental.com

    1. \Device\NPF_{FCFF8C2B-958F-4080-A1B9-0D464447009F} (Intel(R) 82577LM Gigabit
    Network Connection)
    2. \Device\NPF_{D27E2C86-F323-4D6D-8451-1AA70F0F6064} (Microsoft)
    Enter the interface number (1-2):1
    Using Device: \Device\NPF_{FCFF8C2B-958F-4080-A1B9-0D464447009F}
    Waiting for CDP advertisement
    (default config is to transmit CDP packets every 60 seconds)
    Device ID
    value: SEP001EBE923FFF
    Addresses
    value: 10.1.14.132
    Port ID
    value: Port 2

    C:\>
    C:\>
    C:\>cdpr
    cdpr – Cisco Discovery Protocol Reporter Version 1.0.7
    Copyright (c) 2002 – MonkeyMental.com

    1. \Device\NPF_{FCFF8C2B-958F-4080-A1B9-0D464447009F} (Intel(R) 82577LM Gigabit
    Network Connection)
    2. \Device\NPF_{D27E2C86-F323-4D6D-8451-1AA70F0F6064} (Microsoft)
    Enter the interface number (1-2):1
    Using Device: \Device\NPF_{FCFF8C2B-958F-4080-A1B9-0D464447009F}
    Waiting for CDP advertisement
    (default config is to transmit CDP packets every 60 seconds)
    Device ID
    value: GoatSwitch1.goatnetworking.com
    Addresses
    value: 10.1.4.86
    Port ID
    value: GigabitEthernet3/42

    C:\>

  2. I tried this on my Brocade MLXe and SX800, as expected, it didn’t work. I did try Wireshark and was able to see the LLDP packets, but CDPR is much easier then Wireshark.

    Nice find!!

Leave a Reply