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Occasional Contributor II
Posts: 37
Registered: ‎05-17-2012

VLAN Pool question

Hi,

 

We're currently using VLAN pooling with 16 /24 networks using the hash assignments to place clients into the vlans. We have noticed that some networks are becoming full within the pool and clients dont seem to be placed into different vlan, they just hang waiting for a free address to become available in that full VLAN. Is this normal? 

 

Also we are thinking of adding /23 networks to our pools, has anyone mixed their VLAN pools with /23 and /24 networks? if so how was it? 

 

OS 6.4.2.6

6000 series with M3 cards

Many thanks

Guru Elite
Posts: 21,028
Registered: ‎03-29-2007

Re: VLAN Pool question

Pools need to be of the same size.  I would consider even VLAN pool mechanism to balance it out, or a single large subnet.

 

http://www.arubanetworks.com/techdocs/ArubaOS_64x_WebHelp/Web_Help_Index.htm#ArubaFrameStyles/Network_Parameters/Configuring_VLANs.htm?Highlight=even



Colin Joseph
Aruba Customer Engineering

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

Occasional Contributor II
Posts: 37
Registered: ‎05-17-2012

Re: VLAN Pool question

Thanks for the quick reply. 

 

We started off with a large single network and that caused us issues, so we have moved to VLAN pooling. 

 

The issue we have is that we have 16 /24 networks on one M3card with 3500 concurrent users(we see this number increasing too!!). When we hit this level some networks have no free leases and the clients dont seem to be moving to ones which still have space. 

 

At the moment we cant easily find/create 16 /23 networks but can find a couple to swap/add to the current pool but didnt know if this would cause us problems.

Guru Elite
Posts: 21,028
Registered: ‎03-29-2007

Re: VLAN Pool question

What problems did you have with the single large network?

 

The biggest two issues are  to make sure that your layer 3 switch can support large mac address tables and that broadcast filtering is enabled on that Virtual AP.



Colin Joseph
Aruba Customer Engineering

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

Occasional Contributor II
Posts: 37
Registered: ‎05-17-2012

Re: VLAN Pool question

We were having performance issues and advised my support to use VLAN pooling which addressed the problem. Now we have a capacity issue with the pool using /24 networks. 

 

We would like to go to 16 /23 across the pool but they will take time and looking for a quick fix to get us over the issue till then.

Guru Elite
Posts: 21,028
Registered: ‎03-29-2007

Re: VLAN Pool question

If your problem is that devices are not being pooled evenly, please go to the link in the post above to find out how to configure even vlan pooling to deal with your issue.



Colin Joseph
Aruba Customer Engineering

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

Occasional Contributor II
Posts: 37
Registered: ‎05-17-2012

Re: VLAN Pool question

By switching to "even" over hash would that have an impact of clients roaming? we have buildings that are next to each other broadcasting the same SSID but going back to different controlllers with different VLANs within their pools, we have IP mobility enabled to save IP addresses for those clients.

Guru Elite
Posts: 21,028
Registered: ‎03-29-2007

Re: VLAN Pool question

If you have ip mobility enabled, that throws everything out the window, and there is no quick easy solution.

"Even" vlan membership is only calculated locally, so users would not be put into the same VLAN as they were before if they end up on a different controller.  There are a number of ways to slice this, but a single large VLAN that all the controllers are trunked to is the best solution ultimately.  ip mobility can be complex, and it also complicates troubleshooting because you are not always aware what AP a user is connected to, if its traffic is tunneled back to another controller.  It also does not make it easy to add subnets once your pool is 

 

If you use a single large VLAN with broadcast filtering at the Virtual AP level, all of those problems go away...as long as you have a layer 3 switch that can accomodate all of those mac addresses, you should be good to go...

 



Colin Joseph
Aruba Customer Engineering

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

Regular Contributor I
Posts: 236
Registered: ‎04-03-2007

Re: VLAN Pool question

Colin,

Are you advocating for larger subnets over smaller ones? We're using over 30 /22 vlans and I'd like to move toward /18 if possible. Assuming router MAC table is adequate and given we drop bcast and mcast in the VAP is larger subnet the best practice these days?

 

Mike

Guru Elite
Posts: 21,028
Registered: ‎03-29-2007

Re: VLAN Pool question

Mldickson,

Yes.

We are also coming out with a large subnet VRD in the future. We would like to possibly run it past a few users who are candidates for this. If you are interested, please PM me.


Colin Joseph
Aruba Customer Engineering

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

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