Figuring out VLAN config and proper DHCP addresses

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  • Updated 2 years ago
Generally I can hold my own with networking, but for whatever reason I've always had a mental block when it comes to VLANs. Whatever I try, I can't make 100% sense of them.

Next week I'm set to pull our final HP 5400 series switch, making the entire network 100% Aerohive 3-SR2148P's and 20-AP230's. It's a small school, only 20 teachers and 150 kids (250 devices maybe?). I was going to take the easy way out and just go with a flat network with no VLANs.

However, the newly released K-12 Education Deployment Guide convinced me to go with VLANs. Since I'm redesigning, I'm trying to plan for growth.

My block right now is with VLAN configuration. If I have on paper defined VLAN 20 for 10.6.7.1 --> 10.6.8.200, how do I ensure that my DHCP server (MacOS Yosemite with Server.app) gives devices on that VLAN something in that range, and not something else like 10.6.20.x?

On our HP I can see the VLANs defined with their IP and subnet, so it makes sense there. I just can't figure it out in Hive-land.

Basically I'm shooting for something very similar to what's described in Part 2 of the K-12 EDU Deployment guide, except we're not BYOD.

Thanks.
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MiBadger

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Posted 2 years ago

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Malcolm Snelgrove

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No expert, but I will give it a shot. Is your DHCP server only going to serve addresses in that IP range? Do you have a IP Helper/DHCP relay set up to redirect requests?
You can set an Access point to also be a DHCP server and use that, or just connect a DHCP server on an access port in that range. 
VLANs are assigned to users based on authentication of the SSID, and the client then goes looking for a DHCP server in the VLAN, so if you have the DHCP server on an access point of that VLAN, it should respond to a request/broadcast from a client needed a IP address. 
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Aaron Storey

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So your Server needs to have a sub interface configured for VLAN 20 and that is where the DHCP pool will be configured. You then need to make sure whatever port your server connects to on your switch is set as a trunk port. You also need all of the Switch to Switch and Switch to AP ports to be trunk ports. You then assign a VLAN in your configuration depending on SSID and User Profile.
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J. Goodnough, Champ

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In Aerohive-land, you can set default VLANs for user Profiles, it should look like vaguely like this: