Obtaining CDP information on a Windows device Closed     Case # 10039     Affiliated Job:  New Trier Township District 2031 Opened:  Wednesday, May 19, 2010     Closed:  Wednesday, May 19, 2010 Total Hit Count:  19556     Last Hit:  Monday, October 27, 2025 10:20:44 AM Unique Hit Count:  6210     Last Unique Hit:  Monday, October 27, 2025 10:20:44 AM Case Type(s):  Network, Server Case Notes(s):  All cases are posted for review purposes only. Any implementations should be performed at your own risk. Request: I recently needed to grab port information for a server connected to a Cisco switch that has CDP enabled. I didn't want to walk down and map out the cable to the switch port so I began searching out an alternative. Outcome: I found a great article online with how this can be achieved: -    http://windowssystemspecialist.blogspot.com/2006/07/windows-command-line-cdp-capture.html The instructions are pretty straight forward: -    Download the TCPDUMP.EXE    o    http://www.microolap.com/products/network/tcpdump/    o    Has WinPCap built into it. -    Identify the interface to scan:    o    netsh interface ip show interface "Local Area Connection" | findstr /i "index" -    Before running the executable, I found I had to disable antivirus first because some can block this program from running. -    Run the command: (Change the "-i" value to the appropriate Interface #)    o    tcpdump -nn -v -i # -s 1500 -c 1 ether[20:2] == 0x2000 -    The results may be similar to as follows      tcpdump: listening on \Device\{GUID Displayed of Interface}      12:27:13.751768 CDPv2, ttl: 180s, checksum: 692 (unverified), length 284          Device-ID (0x01), length: 20 bytes: 'DEVICEID(CISCO SWITCH/CORE NAME)'          Address (0x02), length: 13 bytes: IPv4 (1) CORE IP ADDRESS          Port-ID (0x03), length: 4 bytes: 'BLADE/PORT#'          Capability (0x04), length: 4 bytes: (0x0000000a): Transparent Bridge, L2 Switch          Version String (0x05), length: 96 bytes:            WS-C6506 Software, Version McpSW: 7.6(9) NmpSW: 7.6(9)            Copyright (c) 1995-2004 by Cisco Systems               Platform (0x06), length: 8 bytes: 'WS-C6506'          VTP Management Domain (0x09), length: 9 bytes: 'DOMAINNAME'          Native VLAN ID (0x0a), length: 2 bytes: 213          Duplex (0x0b), length: 1 byte: full          AVVID trust bitmap (0x12), length: 1 byte: 0x00          AVVID untrusted ports CoS (0x13), length: 1 byte: 0x00          System Name (0x14), length: 7 bytes: 'CISCO SWITCH/CORE NAME'          System Object ID (not decoded) (0x15), length: 10 bytes:            0x0000: 0608 2b06 0104 0109 052d          Management Addresses (0x16), length: 13 bytes: IPv4 (1) CORE IP ADDRESS          Physical Location (0x17), length: 31 bytes: 0x00/TEXT NAME OF LOCATION      1 packets captured      117 packets received by filter      0 packets dropped by kernel