8 weeks of #VCAP – CDP and LLDP

Well, 8 weeks of VCAP has dwindled down into a serious 8 days of VCAP – and for now, how about a little bit of random information from the Networking section of the blueprint.

First up, CDP and LLDP

These are relatively easy to configure, however there are a few different modes that they can be run in, therefore I thought it would be best if I write them down in hopes that maybe I’ll remember them if any scenarios require me to configure them.

Basically the functionality of the two protocols is identical – they both provide discovery of ports connected to a virtual switch.  CDP however supports just Cisco physical switches whereas LLDP supports any switch supporting LLDP.  Another note, CDP can be enabled on both vSphere Standard Switches and vSphere Distributed Switches – LLDP – dvSwitch only!

So let’s have a look at the dvSwitch config first.  Like I mentioned earlier it’s pretty simple. From the properties tab of a vSphere Distributed Switch select ‘Advanced’.  From here its as simple as setting the status to Enabled, the type to either CDP or LLDP, and the Operation mode (explained below).

  • Listen – ESXi detects and displays information from the associated physical switch port, but all information in regards to the virtual switch is not available to the physical switch.
  • Advertise – ESXi presents information in regards to the virtual switch available to the physical switch, but doesn’t detect any information in regards to the physical switch port
  • Both – Does both advertise and listen.


Now that we are enabled we can view what information we receive inside of the Networking section of a hosts configuration tab.  To do so, simply expand out your physical uplinks and click the information icon (shown below).


And that’s all there is for that – with the distributed switch anyways.  To get CDP working on a standard switch we are once again back into the command line interface.  Probably good to brush up on these commands anyways since its also mentioned in the blueprint.  So, Let’s say we wanted to configure CDP on a vSphere Standard Switch called vSwitch0 to a value of Both.  We could use the following command

esxcli network vswitch standard set –v vSwitch0 –c both

And that’s all there is to that – valid options for –c would be both, listen, advertise or down.  To view we could use the same process as above.

  • Tom

    Do note that one a VSS (Standard vSwitch) the default CDP operation mode is listen.

    • mwpreston

      Thanks Tom!!!