snagrat Posted February 9, 2019 Posted February 9, 2019 What is the best way to split VALNs for 900 wireless devices. I could look at doing it per building. The whole campus could have a single SSID but depending on the building you are in it puts you on a different VLAN. How will this work with roaming?
ass17 Posted February 9, 2019 Posted February 9, 2019 We VLAN based on SSIDs not buildings, seems to me to be a better approach given that you would have less SSIDs than buildings = less VLANs to manage between switches/buildings.
richbrowncardiff Posted February 9, 2019 Posted February 9, 2019 (edited) Assuming 300 clients per building i would do 3 x /23 ranges giving you 510 addresses in each subnet the roaming shouldnt be an issue as the SSID and authentication method would be consistent Honestly though if the access to the SSID and the access once authenticated is the same for the clients say for student / staff laptops I would say do 1 /22 subnet giving you 1022 addresses. It all depends on the end game. Hope that helps! Ps you would need a way to broadcast the SSID per building to use a different VLAN for that SSID Unifi that we use is easy to create a Virtual "Site" but it maybe harder for you to do depending on your wireless solution! Normally i would vlan a specific SSID such as staff, Student, Guest etc. Edited February 9, 2019 by richbrowncardiff Correction
HPlum78 Posted February 9, 2019 Posted February 9, 2019 (edited) The answer depends on how the underlying network is setup, if you subnet/ vLAN based on buildings then thats your answer, if you subnet/ vLAN based on device or something along those lines then that your answer. Don't reinvent the wheel unless you are thinking about a whole scale architecture review of your network infrastructure. Edited February 9, 2019 by HPlum78
FN-GM Posted February 9, 2019 Posted February 9, 2019 (edited) 900 is a lot of devices to have in 1 VLAN. Especially on wireless. I would expect performance issues. What wireless equipment do you have? Some support VLAN pools. So you can split the load between multiple VLANS on 1 SSID. I assisted with the installation that had 800 or so devices. We configured 5 x /24 VLANS and the WIFI would balance out the devices between the VLANS. It meant the broadcast was reduced and you could expand easy by adding another /24 if needed. Also no roaming issues! Personally I wouldn't design it so you have more than 254 hosts in the VLAN. Edited February 9, 2019 by FN-GM
mavhc Posted February 9, 2019 Posted February 9, 2019 What's the reason to split them? Broadcast packets? Is that a problem on managed wifi, I thought the controller generally fixed that by knowing where every client was and turning a broadcast packet into a unicast packet sent just to the AP where the client is
snagrat Posted February 9, 2019 Author Posted February 9, 2019 The WiFi vendor isn’t yet confirmed so I will look into VLAN pools. My concern is that 900 devices is too much and just wondered what everyone else did really. We could have separate VLAN per year group, for example?
mavhc Posted February 9, 2019 Posted February 9, 2019 What's too much about it though? What's the specific problem that VLANs solve?
ITGuyWestMidlands Posted February 10, 2019 Posted February 10, 2019 Typically broadcast domains. But, many solutions offer broadcast restrictions on the APs, which only allow them when and where they are needed.
snagrat Posted February 10, 2019 Author Posted February 10, 2019 It appears that most vendors support VLAN pooling. That seems like the best solution
mavhc Posted February 10, 2019 Posted February 10, 2019 Typically broadcast domains. But, many solutions offer broadcast restrictions on the APs, which only allow them when and where they are needed. Right, don't solve the wrong problem. There is an issue with consumer level devices that use mDNS to autoconfig, but they don't scale to school level without help anyway. If that's the case then per building VLAN would at least only give you a list of nearby devices. https://docs.microsoft.com/en-us/surface-hub/miracast-over-infrastructure is an alternative
PotNoodleTech Posted February 11, 2019 Posted February 11, 2019 Subscribing to this as I have not changed my VLANS for about a decade. Got so many more devices now that I think I need to revisit!
leegcvcc Posted February 11, 2019 Posted February 11, 2019 I wouldn't go per building, i did a while ago and it had some issues with roaming. I have gone VLAN per Year group across the site now and it works just fine. Many ways to skin a cat
Davit2005 Posted February 11, 2019 Posted February 11, 2019 As others have said this can be a vendor solution but the vlans per year group and then one for staff should be a workable approach. I wouldn't want to muddy the waters with too many SSIDs. We have one SSID users have different roles and get different vlans i.e. Guests/Students/staff and there are multiple vlan pools. The wireless system was setup prior to me being here but works very well.
chazzy2501 Posted February 11, 2019 Posted February 11, 2019 Vlans really only help manage broadcast traffic, this shouldn't transition past the access point unless you've specifically allowed this. So 1 VLAN, unless you intend to have other policies apply to certain groups. Guest VLAN, Admin VLAN, etc. with different bandwidth constraints etc. but you could do that via SSID on the same VLAN. VLANs need routing so I assume you have a layer 3 core switch that could handle all this? I like the VLAN / SSID but have deviated personally for Guest and Governor Guest access.
snagrat Posted February 11, 2019 Author Posted February 11, 2019 We will have a Layer3 switch at the core. As previously mentioned, VLAN pooling seems to be the answer
AlanD Posted February 12, 2019 Posted February 12, 2019 The Cisco Press CCDA book has this documented in the design section. Generally these are the guidelines. IP - 500 IPX - 300 AT -200 Hybrid (IP/IPX/AT) - 200 If you can, verify traffic loads with a Sniffer. That would show the client their traffic patterns and backup your recommendation of VLANing the network. I think you will find cpu load begins to get increasingly hammered when you get above 250 devices... Especially if these are wireless with printing and bonjour services... I'd probably split the user devices into year groups...
mavhc Posted February 12, 2019 Posted February 12, 2019 The Cisco Press CCDA book has this documented in the design section. Generally these are the guidelines. IP - 500 IPX - 300 AT -200 Hybrid (IP/IPX/AT) - 200 What are IP, IPX and AT?
howartp Posted February 13, 2019 Posted February 13, 2019 We have six VLANS for wifi. 90: APs 91: IT devices permitted to access LAN from WLAN 92: Guests 93: Staff 96: Students 112: Sixth Form Students is a /20 subnet (4096 clients) and Sixth Form is a /22 subnet (1024 clients). We have 1400 students + 300 sixth form, each with up to two devices (phone + tablet) so had to expand them at some point.
AlanD Posted February 14, 2019 Posted February 14, 2019 ... So, I would guess that studs t experience is compromised by having too many devices in one broadcast domain....
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