Want to win a PS4? Go Premium and enter to win our High-Tech Treats giveaway. Enter to Win


Wireless Point to Point Bridge / Tagged VLANS

Posted on 2014-02-06
Medium Priority
Last Modified: 2014-02-07
I have a Customer who has contracted out some Network (Switches , Routers ) Work to a 3rd Party Vendor

They will utilize a Motorola Wireless PTP System we installed a few years ago.

3rd Party vendor has reached out to us and stated the PTP System is not passing Tagged Vlans.

I setup a test on a link 3rd party says fails to function

2 Switches
Switch A - IP: (MGMT VLAN1)
Switch B - IP: (MGMT VLAN1)

Laptop 1 - IP:
Laptop 2 - IP:

Router1 - IP:

Switch Configs (Same on Both)
Port 1 (Access) Untagged VLAN1 (Default),       Forbid VLAN2 & VLAN3
Port 2 (Access) Untagged VLAN2 ,                     Forbid VLAN1 & VLAN3
Port 3 (Access) Untagged VLAN3 ,                     Forbid VLAN1 & VLAN2
Port 8 (Trunk)    Untag VLAN1 , TAG VLAN2 , TAG VLAN3

PTP Equipment plugged into Port 8 on Both Switches
Router1 - Switch1-Port2
Laptop1 - Switch1-Port1
Laptop2 - Switch2-Port2

With This scenario , Laptop 1 cannot ping Router1 and Laptop2 , as expected
Laptop 1 can reach Mgmt/ Ping on Switch 1 and Switch 2

SO it appears that I am able to pass Tagged and Untagge VLAN across PTP

I submitted the results to 3rd Party Net Vendor ...

They knocked it down and said that unless I use different Subnet for each VLAN that it didnt prove anything ...

I guess my question is .. I didn't think VLAN would care what subnet is in use .. or am I wrong ?
Question by:bradwcampbell
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 3
LVL 47

Expert Comment

by:Craig Beck
ID: 39841819
It is well known that some P2P wireless kit strips VLAN tags, especially Motorola kit.  IIRC there was a problem with VLAN tagging which was solved with software somewhere around 2007.

All you need to do to test is connect a device to the same port at each end and see if they can ping eachother.  That will prove whether VLAN tagging is working or not.

On each switch put port 1 in VLAN1, port 2 in VLAN2, etc...
Connnect the PTP link to port 8 (for example) and configure the trunk as you have already.
Connect a laptop to port 1 on the switch at each end and see if they can ping eachother.  As long as they are on the same subnet (forget VLAN now) they should be able to ping eachother.
Move each laptop to port 2 and test again, then move to port 3, etc, etc.
LVL 17

Expert Comment

ID: 39841886
Does the official 802.11 standard even support 802.1q tags?
I've seen them supported with non-.11 wireless kit and custom optical bridges, but not with actual wifi kit. Or it used a separate SSID/vlan.
LVL 47

Accepted Solution

Craig Beck earned 2000 total points
ID: 39842001
The 802.11 standard itself only addresses the PHY and MAC layers IIRC.  That doesn't mean that the radio doesn't allow 802.1Q tags to pass over the link though.

The Cisco 1300 bridge allows 802.1Q tagging as long as the infrastructure SSID is attached to the native VLAN.

Alvarion Breeze[Access/Net] kit can pass 802.1Q tags transparently with no extra config.  These units are fully 802.11 compliant.

A lot of kit doesn't do proper 802.1Q as it doesn't really need to over the air.  A client would connect to an access point and that traffic would be segregated at the SSID level, so the AP only really needs to put that traffic onto the correct VLAN by adding the 802.1Q tag when it leaves the AP to go onto the wire.  

With PTP bridges it's a bit different and many vendors tried to implement it in different ways because it wasn't part of any 802 standard.  Motorola liked to do a lot of proprietary stuff back in their day.  I think it's just down to that but their software release notes indicate that it was supported later on.
Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!


Author Comment

ID: 39842894

We went back on-site today and I appeased the 3rd party Vendor by using seperate IP subnets for each VLAN

This series PTP is the Motorola 49600  (600 Series 4.9Ghz) Public Safety

My setup on switches was as such (Attached), Please critic

Todays Test was sucessful for each laptop talking to a router on the other end of PTP link .. either on untagged VLAN or Tagged VLAN on Trunk

but I am open to any comment why i could be doing this wrong ...

Thanks again for any guidance or thoughts
LVL 47

Expert Comment

by:Craig Beck
ID: 39842914
You didn't really need the routers.  Two laptops would have been enough.

So did you connect the router to port 1 at one end and the laptop to port 1 at the other end?

Author Comment

ID: 39843136
Yes I did and vice versa with second router and laptop...

I didnt think I needed the routers two , but wanted to be able to say to 3rd party Vendor that I was passing traffic at the same time across both vlans to equipment off the router..  to do that I needed some hardware to hit
LVL 47

Expert Comment

by:Craig Beck
ID: 39843153
Ok so as you seem to have proved that the link is passing VLAN traffic, is there an issue now?  Is the vendor still arguing that VLANs are being passed?

Author Comment

ID: 39843363
No word from the vendor ..

Thanks for the review .. I just wanted to be sure that I had tested thoroughly and wasnt missing anything !

Featured Post

Nothing ever in the clear!

This technical paper will help you implement VMware’s VM encryption as well as implement Veeam encryption which together will achieve the nothing ever in the clear goal. If a bad guy steals VMs, backups or traffic they get nothing.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article lists the top 5 free OST to PST Converter Tools. These tools save a lot of time for users when they want to convert OST to PST after their exchange server is no longer available or some other critical issue with exchange server or impor…
In this article, we’ll look at how to deploy ProxySQL.
This video shows how to quickly and easily add an email signature for all users on Exchange 2016. The resulting signature is applied on a server level by Exchange Online. The email signature template has been downloaded from: www.mail-signatures…
Exchange organizations may use the Journaling Agent of the Transport Service to archive messages going through Exchange. However, if the Transport Service is integrated with some email content management application (such as an antispam), the admini…
Suggested Courses

598 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