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New Member

Maximum IP addresses in a single WLAN?

Hi,

We have a WLAN that caters 16000 users. Whether we can have a single VLAN with /18 subnet for the SSID?

I feel like this is a bad design and need to segment it to multiple VLANs. I am not clear on how many IP addresses per vlan can work wothout any single broadcast domain issue.

Please recommend. Whether 1024 IP address subnet will be a optimal solution?

Regards,

Madhan kumar G

7 REPLIES
VIP Purple

Maximum IP addresses in a single WLAN?

HI Madan,

As per my knowledge, The number of clients that you can configure per WLAN depends on the platform that you are using.

Like:

Cisco 2106 Series Controller 350

Cisco 2500 Series Controller 500

Cisco 4400 Series Controller 5000

Cisco 5500 Series Controller 7000

Cisco Flex 7500 Series Controller 20000

WiSM2 10000

Regards

Dont forget to rate helpful posts

New Member

Maximum IP addresses in a single WLAN?

Hi Sandeep,

The data provided by you is the hardware limit on the number of clients, which is a new and useful information for me. Thank you. But , My doubt is on the design of client vlan. If we have a large broadcast domain, whether we will face any issues. How many IP addresses per WLAN is an optimal design solution?

Regards,

Madhan kumar G

VIP Purple

Maximum IP addresses in a single WLAN?

HI Madan,

I never across this kind of question, not  a easy question to answer.

Answer should be:

Yes or No.(You can have as many as you want but there are many limitation )

Two factor:   Bandwidth & Resource

First, the bandwidth you are actually contending for isn't the back end ethernet link, but the wireless link speed. So on a 54 mbps router you would be contending for that 54 mbps. At 60 clients that would be about 900kbps each, not counting TCP overhead, counting TCP overhead you are already down to ~720kbps.

Secondly, you still have to deal with signal strength issues, which depending on your location could greatly effect throughput.

Rule of thumb was about 10-12 clients per AP for best performance, you can probably move that up to 20-25.

*** There is a client limit(Max IP address allocation ) on WLC for each wlan.

http://www.cisco.com/image/gif/paws/113303/restrict-wlan-clients-00.pdf

Regards

Dont forget to rate helpful posts

VIP Purple

Re: Maximum IP addresses in a single WLAN?

I am using /21 (2048 IP) per subnet in my network. For a given SSID I am using 3 of those subnets pool in together using interface group. I am using 5508 as WLC and keep those numbers as database size is 7000 for that platform.

We have similar number  (16k) clients in our main campus, where load is shared onto 4x5508 WLC.

Sent from Cisco Technical Support iPad App

New Member

Re: Maximum IP addresses in a single WLAN?

Hi Rasikanayanajith,

     Thanks for your reply. Did you face any issue in your main campus because of 16k clients in single subnet. Any performance issues kind of?

Regards,

Madhan kumar G

VIP Purple

Re: Maximum IP addresses in a single WLAN?

I forgot to mention, those 4 WLCs are in different layer 3 domains. Anyway since we are using /21 network broadcast domain is limited to 2048 wireless devices.

Each controller is having 6k device capacity using those interface groups which maps 3 dynamic interface of /21 (still broadcast domain is limited to 2k)

We did not have any noticeable issue with those subnet sizing. Also note that only for wireless we are using such large subnet size. For any other /23 is the max subnet size we are using.

HTH

Rasika

**** Pls rate all useful responses ****

Hall of Fame Super Silver

Maximum IP addresses in a single WLAN?

That's a tough question.....I have some clients use a /16 because they didn't want to break up their subnet's that they create long time ago... does it work, yes.  Here is the thing though.... if you wanted to limit bonjour or multicast, how would you do that in a very large subnet.  There are pro's and con's and you have to look at both.  Many of my clients guest networks are /16 and works great, but my clients see that ask guest and use at your own risk.  If your worried about large subnet's, look into interface groups in which you can bundle subnet's together.

http://www.cisco.com/c/en/us/td/docs/wireless/controller/7-4/configuration/guides/consolidated/b_cg74_CONSOLIDATED/b_cg74_CONSOLIDATED_chapter_0100110.html

Thanks,

Scott

*****Help out other by using the rating system and marking answered questions as "Answered"*****

-Scott
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