No announcement yet.

Unable to create VLAN in cisco 3750 switch

  • Filter
  • Time
  • Show
Clear All
new posts

  • Unable to create VLAN in cisco 3750 switch


    I m unable to create vlan id such as(256) in one of our cisco 3750E, IOS 12.2(53r) SE2. The exact error msg is as follows:
    "VTP VLAN Configuration not allowed when device is not the primary server for the vlan database".
    The switch shows 'Server' in the 'sh vtp status' command. The switch is running VTP ver 3. Is it necessary to issue the cmd 'vtp primary vlan' to make this server as primary server even though the primary id of the server already matches in the 'sh vtp status'? There are 2 other switches in the domain as a client mode, what will be the impact of 'vtp primary vlan' cmd on the client vlan dbase?
    The 'sh vtp status' of the main server switch is attached.

    Any suggestions are appreciated.

    Attached Files

  • #2
    Re: Unable to create VLAN in cisco 3750 switch

    According to the Cisco documentation, all switches operating in VTP server mode are secondary servers by default (yes, really). That must be why a switch serving as the only server in a VTP domain can believe it's not a primary server.

    The "vtp server" exec command simply tells the switch it's the primary server. Switches in client mode get their VLAN database from the server switch anyway, and aren't affected by this.


    • #3
      Re: Unable to create VLAN in cisco 3750 switch

      Thanks for the response.
      Making the server primary worked but it's an unusual VTP3 behaviour.


      • #4
        Re: Unable to create VLAN in cisco 3750 switch

        You can follow those steps to help you. Wish this useful for you:
        Step 1 Set VTP mode to transparent.

        vtp mode transparent

        Step 2 Create the primary and secondary VLANs and associate them

        Switch(config)# vlan 20

        Switch(config-vlan)# private-vlan primary

        Switch(config-vlan)# exit

        Switch(config)# vlan 501

        Switch(config-vlan)# private-vlan isolated

        Switch(config-vlan)# exit

        Switch(config)# vlan 502

        Switch(config-vlan)# private-vlan community

        Switch(config-vlan)# exit

        Switch(config)# vlan 20

        Switch(config-vlan)# private-vlan association 501-502

        Step 3 Configure interfaces to be isolated or community host ports, and assign VLAN membership to the host port

        Switch(config)# interface fastethernet0/22

        Switch(config-if)# switchport mode private-vlan host

        Switch(config-if)# switchport private-vlan host-association 20 501

        Step 4 Configure interfaces as promiscuous ports, and map the promiscuous ports to the primary-secondary VLAN pair

        Switch# configure terminal

        Switch(config)# interface fastethernet0/2

        Switch(config-if)# switchport mode private-vlan promiscuous

        Switch(config-if)# switchport private-vlan mapping 20 add 501-502

        Switch(config-if)# end