Cisco IOS // Trunk Discovery Protocols (CDP DTP VTP)

Disabling CDP

show cdp
show cdp neighbors
show cdp neighbors detail
!clear cdp counters
!clear cdp table
show cdp entry * protocol
show cdp entry * version

eventually disable CDP

config t
no cdp run
no cdp advertise-v2

or per interface

config t
interface fa0/X
switchport nonegotiate

More on VTP

only pass the VTP advertisements through trunks

vtp mode transparent
!set vtp mode transparent

check your configuration

show run | include vtp
show run | include vlan
!show interfaces
show interface fa0/1
show interface fa0/24
show interface gi0/1
show interface gi0/1 trunk
show interface gi0/2
show interface gi0/2 trunk

check your VTP Version, Domain, Revision

show vtp status

check operations and password setting

show vtp counters
show vtp password



Chapter: CDP Commands

show cdp neighbors

How could I know what is the native-vlan on the neighbor device?

CDP Neighbor over multiple vlans


Disabling Dynamic Trunking Protocol (DTP)

Disable DTP on a switch


Understanding VLAN Trunk Protocol (VTP)

Configuring VLAN Trunk Protocol (VTP)

Troubleshooting VLAN Trunk Protocol (VTP)

Cisco Discovery Protocol Configuration Guide, Cisco IOS Release 15M&T

How a Recently Inserted Switch Can Cause Network Problems

Reset the Configuration Revision Number

Switches not updating VLAN’s

The VLAN configuration changes do not update on a switch due to the misconfiguration of the VTP and the “VLAN 1003 parent VLAN missing” error message appears