This article explains about VC ports not being seen in the output of "show LLDP neighbors" command.

In the output of "show lldp neighbors" we see the interfaces of Link-level type: Ethernet, when the lldp protocol is enabled for all interfaces.

The below VC Ports are present on the switch however are not seen in the lldp neighbors output:

user@switch> show virtual-chassis vc-port all-members

fpc0:

--------------------------------------------------------------------------

Interface   Type              Trunk  Status  Speed    Neighbor

or                             ID            (mbps)   ID  Interface

PIC / Port

1/0         Auto-Configured     3    Up      1000      2   vcp-255/1/0

1/1         Auto-Configured     3    Up      1000      2   vcp-255/1/1

Typically, VCP interfaces (used for internal communication between the switches in the virtual chassis) do not show up in the output of the "show lldp neighbors" command. This is because VCP interfaces are primarily used for internal virtual chassis communication and are not standard Ethernet interfaces that advertise LLDP information. We can enable or disable the LLDP protocol on an ethernet/network interface. With the LLDP protocol being enabled on a network port, this helps in auto-conversion to VC port if these interfaces are connected to the members of the VC. However, once the network port is converted to VC port, if we try to enable or disable the LLDP on VCP below error is seen:

{master:0}[edit]

root@jtac# set protocols lldp interface vcp-255/1/0

error: name: 'vcp-255/1/0': Invalid interface

error: statement creation failed: interface