Planning 802.11ac

[jmprats]

I'm planning  migrating to 802.11ac with a WLC 5508.

But it seems the controller is going to be a bottleneck in this network design

Each AP pushing 1 Gbps to the controller with an 8-port controller. So the WLC  can only support 8 concurrent 802.11ac sessions, right?

It's like, the controller design doesn't fit well with 802.11ac.

What do you think?

Any design recommendation?

Thanks

[Stephen Rodriguez]

the honest answer? It Depends....

You an definitely get more than 8 clients working at a time before you start seeing a bottleneck happening.

Part of what you have to remember is that wireless is half-duplex. So if your client sees a connection rate of 400M, the most realized throughput they are going to see is probably about 60%, and more likely down around 30%.

There are other factors as well, including how big of a channel bond are you using? How many spatial streams are the clients you are supporting? are your switch links 10G or 1G? and more

HTH,

Steve

[jmprats]

It seems that a design with local switching AP's has more sense for 802.11ac, than all the traffic going to the controller.

And if we have a bottleneck with 802.11ac, even more with wave2 than is coming next year.

They are only thoughts, but i suppose Cisco is thinking about that to decide where is going with wireless. In fact,  there isn't a Cisco design guide for 802.11ac. And for the moment, they have bought Meraki.

It would be interesting knowing about any real experience with 802.11ac

[Rasika Nayanajith]

Each AP pushing 1 Gbps to the controller with an 8-port controller. So the WLC  can only support 8 concurrent 802.11ac sessions, right?

WRONG.

Think about your wired network. For 1G uplink switch how many 1G downstream ports you have provided ? As per your analogy only single port should be given (1:1 subscription) . But you may provide 48, 96, or even 200 1G downstream ports from a single 1G uplink port. Have you noticed your 1G uplink saturated by these downlink ports traffic ?

Same apply even if you plug 3700 for these wired ports. Traffic won't be constant 1G from these. So you have to use same oversubscription ratios as wired when you design.

We have a production network where 80-100 3702I connect to single 5508 & even I could not see traffic hitting more than 1-2Gbps (out of 8G total). 

So 5508 with central switching is NOT a bottleneck unless you have huge traffic demand & large number of 3700 (eg 500 AP) deployment. 802.11ac does not mean your consumer traffic demand is increased just because of 802.11ac (like we moved from 100Mbps to 1Gbps for wired. You may have given 1G port to wired users, but their actual traffic demand can be fulfil with 100Mbps). You have to plan your switch network rather any thing else as that will be the bottleneck if at all.

Wave-2 is different & you need to see how can you give more than 1G to your AP from a switch.(10G or multiple 1G). Also do you have enough frequency to use 160MHz in your enterprise environment.

HTH

Rasika

**** Pls rate all useful responses ****