I have an outdoor venue where I'm planning a wifi network, the venue covers 350 meters by 350 meters. This is not a question about equipment but only about the planning in theory. I will deploy multiple access points across the site on different channels with the same ssid.

Should I divide the area in to several small vlans / dhcp scopes, or is it better to create a large dhcp scope like a /21?

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    – Ron Maupin
    Aug 9 '17 at 1:45

its never a good idea to create to large Broadcast domains.

Imagine, 1 client sends an broadcast(maybe an arp-request), all 1500+ user have to deal with it, its a waste of bandwith.

if its fit your setup and you habe enought IPs make smal scopes to avoid high basic-noise on your Network


As discussed below if you like to use WLAN-Roaming you can span a big L2-Broadcastomain and use client isolation, to avoid broadcasts flooding your Network.

  • 1
    Re: "its never a good idea to create to large Broadcast domains." There are some very valid cases for large broadcast domains, layer2 wireless roaming is one of them. Now it remains to be seen whether the OP really needs layer2 roaming. Based in the very brief description in the question, I don't think he needs it; however, let's not over-generalize the broadcast domains point. Aug 5 '14 at 11:23
  • @ Mike Pennington Ok, you have right i didnt note L2-roaming. But with 1.5k User, you have to deal with the Broadcasts. If you like to use phones in your WLAN i would suggest, to create a seperate SSID and VLAN just for the Phones. Because you should use higher QOS-level for the phones than for other clients.
    – chris
    Aug 5 '14 at 11:35
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    I disagree that the number of endpoints in the wireless domain is going to matter; at least cisco wifi controlllers block broadcast propagation between clients by default. FYI Cisco Live 2014 used a 16-bit netmask (i.e. they put over 25,000 engineers with laptops and phones in one subnet). I was there and used the CLUS2014 wireless... quite honestly, it was a work of beauty Aug 5 '14 at 11:38
  • They proably have some filter at L2, i could imagine Client => AP => L2-Proxy(doing some filter stuff) => L2-Domain. Whitch WLAN-Phones does they use? If they used Cisco WLAN-Phones they Propably used CNDP to put them automaticly in an seperate VLAN with better QOS.
    – chris
    Aug 5 '14 at 12:07
  • Regardless of whether they allowed peer to peer wifi traffic, the point remains that they used a very large subnet; CLUS2014 deployed a single layer2 wireless network with 65000 potential address. BTW when I mentioned phones, I mean cell phones such as Android or iPhone. Aug 5 '14 at 12:14

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