How to change a vlan ID?

Posted on 2008-11-12
Last Modified: 2012-05-05
I got info comming in vlan X and that same info I need to forward it as Vlan Y.
Vlan X is comming from external provider and I seem to have the same Vlan X already in use in my internal network. For me would be too difficult to change Vlan X in my internal network.

Question by:netlach
    LVL 50

    Accepted Solution

    Unless you're trunking, the VLAN ID is not relevant. It's locally significant. Or put another way, when the frame arrives at your switch, there is no VLAN ID on the frame.

    Now if the incoming link is a trunk link, then you'll have to change your internal VLAN number.
    LVL 4

    Assisted Solution

    What equipment are you using? Higher end provider gear (like Cisco 7600 f.ex.) can do VLAN translation.

    If you don't have a switch that can handle VLAN translation, then you might take the VLAN traffic from outside and send it out an access port (in effect removing the VLAN ID) and then take it in an access port that is a member of the VLAN ID that you want to translate it to.
    LVL 3

    Assisted Solution

    What you can do is: plug the cable of your external provider( VLAN X ) in a port with just access to VLAN Y, and you don't need extra configurations.

    Author Comment

    Your Switch A has a  provider  connected  in int Gig9/17. This  provider sends you  data  in  multiple vlans, lets say vlan 10, 11, 12,13, 14 y 15. But  you  are  using  this  Vans  IDs as  well  in your network.
    What  you  can do is  "mapping"  the  Vlans  to other numbers. Interface  configuration  would look like this:

    int Gigt9/17
     description Provider_MultiVlan
     switchport trunk encapsulation dot1q
     switchport trunk allowed vlan 10-15,310-315
     switchport mode trunk
     switchport nonegotiate
     switchport vlan mapping enable
     switchport vlan mapping 10 310
     switchport vlan mapping 11 311
     switchport vlan mapping 12 312
     switchport vlan mapping 13 313
     switchport vlan mapping 14 314
     switchport vlan mapping 15 315
      no ip address
     load-interval 30
     no cdp enable

    You  need  to  create   all vlans first.
    Then   to  get the provider's traffic coming  in Vlan 10, config  a  port  in your  switch  to  be in vlan 310 and  so on.

    interface GigabitEthernet1/8
     description ServerGettingProviderTraffic Vlan 10
     switchport access vlan 310
     switchport nonegotiate
     no ip address
     speed 1000
     duplex full
     spanning-tree portfast

    I hope  this  helps you.


    Featured Post

    Better Security Awareness With Threat Intelligence

    See how one of the leading financial services organizations uses Recorded Future as part of a holistic threat intelligence program to promote security awareness and proactively and efficiently identify threats.

    Join & Write a Comment

    The worst thing when starting a new job is when the previous Network Administrator left behind no documentation. How do you get into the devices? If you've been in this situation or just accidently mistyped your password, this article will hopefully…
    As dyndns has reduced the capabilities of the free service, I looked around for other free providers of Dynamic DNS service. After testing several I decided to move my DNS hosting to Hurricane Electric as then domains that require dynamic hostnam…
    This video gives you a great overview about bandwidth monitoring with SNMP and WMI with our network monitoring solution PRTG Network Monitor ( If you're looking for how to monitor bandwidth using netflow or packet s…
    In this tutorial you'll learn about bandwidth monitoring with flows and packet sniffing with our network monitoring solution PRTG Network Monitor ( If you're interested in additional methods for monitoring bandwidt…

    745 members asked questions and received personalized solutions in the past 7 days.

    Join the community of 500,000 technology professionals and ask your questions.

    Join & Ask a Question

    Need Help in Real-Time?

    Connect with top rated Experts

    19 Experts available now in Live!

    Get 1:1 Help Now