VLAN design question

Unanswered Question
May 10th, 2008

Hi folks,

If I want to design an infrastructure for voice, video and data like NGN, which one is the best practice:

* VLAN per service?

* VLAN per user?

How do I assing the ID for those VLANs?

Where can I find more information about it?

Lots of questions (sorry) and thanks in advance for your help.


I have this problem too.
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waleed_amer Sat, 05/10/2008 - 05:31

Hi friend,

if you have many users vlan numbers will not be enough to use one per user, so if you have one site it is good to use vlan per service and if you have many sites and all those sites connect to common broadcast domain you will have problem with broadcast traffic between sites so you can use vlan per service per site (ex. Site 1 and date = vlan 11, site 15 and voice = vlan 152).

Regards, W.Amer

omendieta77 Sat, 05/10/2008 - 06:01

Thanks for your help Waleed

if I have a network infrastructure to provide triple-play services and I want to separate traffic using vlan per service. There will be DSLAM for example to concentrate users at the access Layer, and then it will route traffic to the Agregation layer. The question is if I want a VLAN per service (3 in this case) I will need just 3 vlans? or I should take any other variables in order to know the total number of vlans that I need ?

maybe if you know a useful link.

I really appreciate your help,

Have a nice day,


tj.mitchell Sat, 05/10/2008 - 12:33

What your asking is sort of a loaded question. It's hard to state how many VLANS to have. First let's look at this:

How many users are on the network total.

How many users total per site.

Is the building broken up by floors? How many?

Then, how many users per floor and do you split the users per department?

Also, how many access switches?

How many closets are per floor, do they all terminate into the same MDF? Are there multiple runs per closet.

This is just being of the list of questions that I would have for you, so I believe that you have a loaded question.

omendieta77 Sun, 05/11/2008 - 04:01


thanks for your suggestions.

I can provide the answers for your questions.

How many users are on the network total?


How many users total per site(8)


Actually this is a small project for triple-Play services...so I must decide how many VLANs I should provide per DSLAM.

According to the text I've read it would be a good practice to have 1 VLAN per service and I would be answering my own question :=) but I don't know if I should consider more variables..for example if additionally I need a VLAN per site??

thanks in advance, have a nice day.


tj.mitchell Tue, 05/13/2008 - 04:38

With 1660 users per site, I would look at separating out the users into departments then subnet them out. Then do the same thing for all the different services. Separate out the VLANS per service per department or closet/building location. Also, I would look into a routed design to help eliminate STP and check the timers of the routing protocol to best practices from Cisco.

Thanks if this helps please rate...


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