Cisco / Trunk Discovery Protocols


Disable DTP

do show cdp
no cdp run
no cdp advertise-v2

or per interface

interface fa0/X
switchport nonegotiate


show cdp neighbors
show cdp neighbors detail

Chapter: CDP Commands

show cdp neighbors

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

CDP Neighbor over multiple vlans

check CDP

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

eventually disable CDP

!config terminal
!no cdp run
!no cdp advertise-v2
!!cdp run
!!cdp advertise-v2

disable per interface

!interface ...
!no ip address
!no cdp enable
!!cdp enable


set vtp mode transparent

check your VTP Version, Domain, Revision

show vtp status

check operations and password setting

show vtp counters
show vtp password

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 vlans

show vlan

vlan database


Command Line Reference

Cisco IOS Configuration Fundamentals Command Reference

Chapter: Basic Command-Line Interface Commands

Command References

CLI Reference Guide


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

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