Log In

Come Join Us!

Are you a
Computer / IT professional?
Join Tek-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Tek-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


vlans and tags

vlans and tags

vlans and tags

     I have been told vlan tags are locally important
only.  This seems counter intuitive to me.  It seems like
if I send out packets tagged with vlan id of 1 that they
could be routed or sent to other switches vlan 1.  And if
they were both not in the same subnet, they would not be able to communicate.
      ie- switch a vlan 1 /24 mask
          switch a vlan 2  /24 mask

          switch b vlan 1  /24 mask
          switch b vlan 2   /24 mask

   In this example switch a vlan 1 to switch b vlan 1, ok
to communicate.  But switch a vlan 2 to switch b vlan 2, no
communication.  Thanks for your time.

RE: vlans and tags

That's correct. If you want switches a & b to be on the same physical network you *should* have a universal VLAN/subnet scheme for the network.

RE: vlans and tags

Indeed you are totally correct.
For vlans or different subnets to communicate with eachother you'll need a router.

RE: vlans and tags

You have to look at the bigger picture.  VLAN Tags are only significant within the Layer-2 domain; as soon as they reach a Layer-3 boundary (the gateway or next-hop) and get routed then the 802.1q VLAN header is discarded.

If you have big Layer-2 domains and VLANs spanning a large network then you have a problem.....  Draw a picture of the topology.


Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Tek-Tips Forums free from inappropriate posts.
The Tek-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Tek-Tips forums is a member-only feature.

Click Here to join Tek-Tips and talk with other members!

Close Box

Join Tek-Tips® Today!

Join your peers on the Internet's largest technical computer professional community.
It's easy to join and it's free.

Here's Why Members Love Tek-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close