Configuring the Cisco Discovery Protocol (CDP) with ESXi

Products

• VMware vSphere ESXi

Issue/Introduction

ESXi hosts have the ability to use the Cisco Discovery Protocol (CDP). The article describes configuring the host and provides an example configuration of a physical switch.

Environment

VMware vSphere ESXi 6.7
VMware vSphere ESXi 7.0.0
VMware vSphere ESXi 8.0

Resolution

To configure CDP for a Standard vSwitch:

 

1. Log in as root to the Service Console (via SSH, remote console, or physical console if connecting to ESX) or to management vmkernel port (if connecting to ESXi).
    
2. Verify the current CDP setting for the desired virtual switch (vSwitch1, in this example):
   
   # esxcfg-vswitch -b vSwitch1
   
   You see an output similar to:
   listen
   
   The output of listen indicates CDP is configured to read CDP information from the physical switch if available.
   This is the default setting for ESXi.
    
3. Set the CDP status for a given virtual switch. Possible values here are down, listen, advertise, or both.

_{Down Mode - The  Esxi host disables CDP.}

_{Listen mode - The ESXi host detects and displays information about the associated Cisco switch port, but information about the vSwitch is not available to the Cisco switch administrator.}

_{Advertise mode - The ESXi host makes information about the vSwitch available to the Cisco switch administrator, but does not detect and displays information about the Cisco switch.}

_{Both mode - The ESXi host detects and displays information about the associated Cisco switch and makes information about the vSwitch available to the Cisco switch administrator.}

     # esxcfg-vswitch -B both vSwitch1

      4. Verify the new setting:

     

     # esxcfg-vswitch -b vSwitch1
 

           You see an output similar to:

      both

To configure CDP on a vNetwork Distributed Switches (vDS):

1. _{Connect to vCenter Server using the vSphere Client.}
2. _{In the vCenter Server home page, click Networking.}
3. _{Right-click the vDS and click Edit Settings.}
4. _{Select Advanced under Properties.}
5. _{Using the checkbox and the drop down, change the CDP settings.}

The following is an example of configuring CDP for a Cisco 6500 physical switch:

1. switch#
2. switch# config terminal
3. switch(config)# cdp run
4. switch(config)# interface g1/1
5. switch(config-if)# cdp enable
6. switch# show cdp neighbors
   
   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
   pa-tse-h24.pasl.vmware.comGig 1/1 121 S VMware ESXvmnic2
   pa-tse-h24.pasl.vmware.comGig 1/2 121 S VMware ESXvmnic3