Three different wireless networks on a single AP?

[Barty_1]

Hello again,

I wanna know if it is a good idea to have three different wireless networks on a single AP. I've seen in the VSC settings that i can change the wireless rates for the different networks.

Should the APs be on different rates or should the different network be on different rates?


//Barty

P.S. This thread has been moved from Communications, Wireless (Legacy ITRC forum) to MSM Series. -HP Forum Moderator

[kianwei]

Barty,

I believe is a MSM AP here because as you mentioned you allow to set different data rates for different VSC.

The AP is make to be working in multiple SSID (or we call it VSC) environment. Every VSC can have different setting depend on your requirement. It won't effect the performance of the AP.

Performance of the AP will only drop, if a lot of wireless user try to connect to particular same AP. (FYI, AP bandwidth is shared in between users that connected)

Hope will this help you.

[Barty_1]

So theres no need to change the wireless rates for the different VSCs?

[Fred!]

The rates in the VSC are made to allow you to accept (or not) clients with specific rates on that particular SSID. Basically, it is a way to filter out the less performant stations and to prevent them from connecting and accessing your AP.

In other words, typically in that case, one may want to remove some of the lower rates and only accept higher rates. This will "force" the stations that are further away from the AP to seek another one that is most likely closer and where the rate negotiation could be higher.

The reason for this is that if a client connects to a particular VSC at a high rate (let's say 54Mbps on a g radio) and another client connects to a lower rate (let's say 11Mbps on the same radio), the one that has a lower rate will "drag" down the performance of the one with a higher rate. The reason behind this is again that they are sharing the same radio, and the radio needs to adjust to transmit/receive data at a proper rate (as negotiated with the client). Now, eliminating the lower rates could help in improving performance, but has some drawbacks. Some clients will not like it (they need the lower rates), and also you need to make sure you have sufficient AP coverage for clients to be able to choose a closer AP or they will simply disconnect from the network.

Bottom line, the rates and the number of services you want to offer are not linked together. The rates is a way to balance or fine tune the performance that you expect out of your AP. It is per VSC to provide the flexibility on some critical application VSC to remove some of the lower rates and it helps in some cases. But generally, you don't touch them unless absolutely needed (it needs to be carefully planned to avoid the drawbacks mentioned above).

Hope that helps!

[Mikko Peltoniemi]

What about for things like a guest network? I'm throttling the throughput at the firewall. There is no LAN access with the guest VSC. There are other VSCs for cordless phones and LAN access.

Would there be benefit from disallowing some of the higher rates for the guest VSC? Like I said it's already being throttled at the firewall, but maybe this would prevent the guest devices from hogging up the airwaves?

[Fred!]

You can also use QoS at the AP/VSC level to put less priority on the guest traffic (compared to the other type of traffic that you have).

I mean it is far from easy. The idea is to achieve a fine balance between rejecting the users "beforehand" or still accepting them, and accepting some degradation and limit their use of the network. The is not perfect magic answer to this I'm afraid.

The other issue that you will face is on the client side. I experienced situations where MAC/Apple products do not like the fact that they can't talk at lower rates. Even if you tell them they are not available, they are stubborn and still send the information at lower rates.

Bottom line, there is nothing easy in that area and it all depend on what kind of problems you are ready to live with. Ultimately removing lower rates helps the performance, but reduces the "cell size" and excludes far away clients as well as not well-behaved clients (like the Apple stuff).

I would say experiment is your best friend here as I'm afraid as every environment is kind of unique and it is really tied to what matters the most to you: ultimate performance or accomodating most/more users. I'm afraid it is always a balance and it is not quite simple.

I wish clients and APs would be more intelligent, and they will with the new standards coming up (11k, 11v), but right now there are simply no perfect tool to fine tune your global wireless environment (which is not just the APs but the clients as well). Just tricks you can apply and see the result in your environment and see if you need to adjust as you go...

(I mean that's my opinion/experience, and I don't pretend it is the ultimate truth!)