DHCP Best practice recommendation

[dave_bauman]

Greetings,

We are working on some deployments where there will be multiple non-connected gateways within a venue space and WiFi users will be roaming between them.  We use a vSZ for the controller. 

The easy, but probably not the best way to deploy this is to run DHCP on each of the gateways on different subnets, but that might pose a roaming wireless user going between WAPs on different gateways.

Another idea we had is to use a centralized DHCP server so the WiFi client can easily retain their IP as they flow through each gateway, but I expect that we will need to use an identical LAN gateway IP on each gateway which would be ok in some instances, but we also VPN traffic from each gateway to our Datacenter (where the DHCP server will also be).

Does the vSZ have any good way of forcing a WiFi client to quickly re-DHCP as they flow through different WAPs that are on different networks?  Any other options I should be looking at?

[gary_simants]

Hi Dave, you could go with the DHCP option on each of the gateways and have a client L3 roam between the access points but this will likely cause issues for real time traffic.

The option I would suggest is using a centralised DHCP server in the data centre along with a Virtual Data Plane (V-DP). This way you could tunnel all the client traffic back to the VDP and break out from there using a centralised gateway.

Gary

[dave_bauman]

Copy that, makes sense.  I have not really used the VDP before as I always have a concern about the vSZ ability to route significant traffic loads.  There is also the concern about performance over tunnels as well.  My additional concern would be how this traffic loads across a vSZ cluster where each vSZ is located in different datacenters.

[gary_simants]

We run clustered VSZ’s and clustered V-DP’s In different data centres and haven’t had any routing or tunnel issues.

Traffic to the VSZ’s will be low as it’s only management traffic, so shouldn’t be to much of a concern. There is also the option to balance the traffic across the VSZ’s and doing this normally keeps the load pretty even across the cluster.

If you were to run multiple VDP’s as well you can create zone affinity profiles to send traffic to specific Data planes to balance the traffic.