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Frequent Contributor I

VLAN Pooling Best Practice

We have always just run one huge vlan for or wireless(student in 1 and Fac/Staff in another).  We have outgrown our current vlan which is a /20, so it looks like pooling is the way to go.  What size is considered best these days?  A while back it was lots of smaller vlans, and then i thought i read recently that its ok to go larger since the software has gotten better at managing broadcast traffic and whatnot.  

 

What is the current best practice recommendation for subnet sizes with vlan pooling?  We are running 6.4.1.0 and i will update to 6.4.2.x whenever it goes GA if that matters at all.  

Guru Elite

Re: VLAN Pooling Best Practice

There is no best practice.  You can make them as large as you want, as long as you have "Drop Broadcast and Multicast" enabled on your Virtual AP, you should be fine.

 



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Frequent Contributor I

Re: VLAN Pooling Best Practice

As always thanks for the quick reply.  I do have Drop Multicast enabled and i have not noticed any performance problems with multicast so i just wanted to make sure.  

Re: VLAN Pooling Best Practice

You can grow the subnet to a maximum size of /16 on ArubaOS, that's the maximum size of the ARP cache.

 

We have several universities running /18s.

 

Levi's Stadium is using a /16 and it works very well.   

 

You need to double-confirm that your core infrastructure CAM tables also scale to this size.


-cl
Frequent Contributor I

Re: VLAN Pooling Best Practice

Followup:

I created the pool and have it assigned to the student role, however noone is getting assigned to the new subnet.  I can watch the 2 dhcp pools and the original one changes all the time, while the new one is not getting any new address pulled from it.  If i set the student role to use just the new subnet they pull address just fine but if i set it back to the pool it only uses the old one.   

 

The VLAN pool is set to balance evenly, not via hash.  Am i wrong in assuming that something is not right here?

Guru Elite

Re: VLAN Pooling Best Practice

The VLAN Name, or Pool, should be assigned to the Virtual AP, NOT the role...



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Frequent Contributor I

Re: VLAN Pooling Best Practice

Except i am using clearpass and i only want the users with the AD role of Student to get put into the vlan pool.  Right now fac/staff and students each get their own vlan assigned to them via Clearpass, and it is assigned at the user role level on the controller.  If i cannot use the vlan pool with a user role why does it give me the option to select it?

Guru Elite

Re: VLAN Pooling Best Practice

mwallen,

 

I probably should ask you to open a new thread... :(



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

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