AP direct connection to the Cat 3850

Answered Question
Feb 14th, 2013

Hi guys,

APs must be directly connected to the 3850 for it to work in MA or MC mode. But if we add some switches and configure it to work transparently (without CDP/ VLAN tagging /LDP ) ?

Do you think this is really not possible to make it? What impact CAPWAP tunnel gets from this transparent switch?

I have this problem too.
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Correct Answer by Leo Laohoo about 1 year 2 months ago
But I'm asking: is it possible? ( to have active CAPWAP tunnel from 3850 to AP, while using transparent switch between these).

According to the presentation, you "can" do this but it won't work well.

Just think about it, you have a transparent switch downstream and it's connected on a 1 Gbps interface to the 3850.  Let's say your transparent switch has ten 802.11ac-capable APs.  Now throw, say, 5 people (per AP) and they are in close proximity to the AP that they can push 802.11ac speed.

I'm just saying that before you want to be creative, test these out.  You'd want to go to your management and confidently say, "If you want to do this, then you'd be prepared because it ain't going to work well."  And then show them your proof. 

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Stephen Rodriguez Thu, 02/14/2013 - 06:58

I think this would still fail, as the 3850 would see multiple AP's coming from one port

HTH,
Steve

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EvaldasOu Thu, 02/14/2013 - 07:00

Good point Stephen, but if we will do some one on one mapping? One port for one AP?

Leo Laohoo Thu, 02/14/2013 - 14:33
Good point Stephen, but if we will do some one on one mapping?  One port for one AP?

Won't make any difference.

The main objecting for this new wireless architecture is "keep local traffic local".  Just image if you implement 802.11ac and, say, you have a 10 Gbps uplink to the distro or core.  If you don't implement the new architecture, this means less than 10 AP running 802.11ac traffic can seriously overwhelm your LAN to it's knees.

If you directly connect the 3600 to the 3850 then CAPWAP traffic is completely stripped upon ingress to the 3850.  And the wireless traffic is treated as ordinary wired traffic.

If you stick another switch to the 3850, this means that a single 802.11ac AP can overwhelm the link.  Again, this does not make sense. 

janesh_abey Thu, 02/14/2013 - 21:32

"keep local traffic local" to me this sounds to like hreap

compared to ethernet the capwap overhead is very small.

by stripping off the capwap at ingress we are not saving a lot.

what am i missing here?

Leo Laohoo Thu, 02/14/2013 - 23:26
by stripping off the capwap at ingress we are not saving a lot.

Not alot ... if you are counting on a per-AP-basis.  Multiply that number to 50 AP and it might mean alot.   Then factor in multiple chassis of 3850 ...

According to the presentation, stripping off the CAPWAP-related messages and converting the wireless traffic into normal wired traffic can minimize bottlenecks in your uplinks.  Now I am to presume the uplinks involved is around 4 Gbps in an Etherchannel.

Another thing is trying to make the 3850/Sup8 make the decision locally instead of sending the stuff all the way up to the core where your controllers are.

And yes, this sounds like H-REAP because this new design is very beneficial to people running H-REAP.

I'm still at a doubt, for example, if I have sites that are connected on dark fibre (like ours). 

janesh_abey Fri, 02/15/2013 - 15:43

apologies for hijacking the topic..          

Leo,   u  arereferring to a presentation..is that something available for the general public?i would like to see it sometime. based on thereviews from other members at  this point i'm bit cautious about deplying 5760 as the doco does not explain in greater detail  how some of the features work.

Leo Laohoo Fri, 02/15/2013 - 15:55
arereferring to a presentation..is that something available for the general public? 

Talk to your Cisco SE for Wireless.  They have this presentation.

Until Cisco officially releases the final copy of the new wireless design, everything is up in the air.

I did throw the question about how this new wireless design would fit into our network particularly when we have fibre to nearly all our sites.  The SE's response was:

1.  This design will benefit companies with H-REAP/Flexconnect; and

2.  When you are serious about deploying 802.11ac to the entire building (not just here and there).

EvaldasOu Thu, 02/14/2013 - 23:01

Yes Leo,

from Architecture and Deployment view this is not a solution or recommendation. But I'm asking: is it possible? ( to have active CAPWAP tunnel from 3850 to AP, while using transparent switch between these).

Correct Answer
Leo Laohoo Thu, 02/14/2013 - 23:30
But I'm asking: is it possible? ( to have active CAPWAP tunnel from 3850 to AP, while using transparent switch between these).

According to the presentation, you "can" do this but it won't work well.

Just think about it, you have a transparent switch downstream and it's connected on a 1 Gbps interface to the 3850.  Let's say your transparent switch has ten 802.11ac-capable APs.  Now throw, say, 5 people (per AP) and they are in close proximity to the AP that they can push 802.11ac speed.

I'm just saying that before you want to be creative, test these out.  You'd want to go to your management and confidently say, "If you want to do this, then you'd be prepared because it ain't going to work well."  And then show them your proof. 

saravlak Sat, 05/04/2013 - 16:45

AP indirectly connected to 3850 AP may join however doesn't beacon, it appears either ssid is disable or radio is shut.

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