Simple VLAN question

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Aug 7th, 2008
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What is the maximum number of user in a single vlan. What does Cisco recommend?


Thanks

Correct Answer by Tarun Lohumi about 8 years 11 months ago

Number of VLANs and Users


The maximum number of users that you can define per known network is 1000.


Cisco recommends that a VLAN contain no more than 150 to 200 users.


http://www.cisco.com/univercd/cc/td/doc/product/rtrmgmt/sw_ntman/cwsimain/cwsi_1/cwsi1_ug/vldug/design.htm

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bmbreer Thu, 08/07/2008 - 08:52
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That really depends on a number fo things, for instance, what type of application traffic is there in the vlan, etc. There's no one single answer that will fit all situations.

bprinski Thu, 08/07/2008 - 08:55
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So not even an average, that you can go by?

Jon Marshall Thu, 08/07/2008 - 08:54
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There is no strict limit as such but the general recommendation is to use a Class C per vlan. However this is very generic and you need to take into account


1) Broadcast traffic on the vlan

2) Security issues - ie. does it make more sense to have smaller vlans that you can control the traffic between

3) Does your user base fit into a vlan design as such ie. marketing dept gets one vlan, sales another vlan etc.


Where i used to work we used /25's per vlan ie. half a class C. These worked well.


Jon

bmbreer Thu, 08/07/2008 - 11:30
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Tarun,


I'm curious what this 1,000 user limit per vlan is based on. I read the webpage you referenced but it doesn't explain why. What would keep me from having 1,200 users per vlan.


Jon Marshall Thu, 08/07/2008 - 12:17
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Tarun


I, like Brad, am also curious about that statement. Vlans have no concept of users as such so i'm really curious to know why the limit is 1000. Surely i could use a class B address range and have everybody in vlan 1 ? - admittedly not something i would do and it wouldn't work very well :) but i'm not aware of any limitation that would stop me doing that.


Thanks


Jon

Joseph W. Doherty Thu, 08/07/2008 - 15:06
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It's an old doc, original copyright '89. Notice it's using the 3000 and 5000 in its example. Perhaps 1,000 users was some limitation of one or both platforms at the time.

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