Hi Kevin,
These are a lot of questions in just one post. Let me try to capture them all, but, before I begin, I would recommend you to have a close look into this document:
Cisco Catalyst 3850 Switch Deployment Guide
For your first question, this is a definite NO. The Converged Access deployment mode is an option for branch offices as well as for large campuses. As you will be seing here (the entire paragraph is very useful to understand the different deployment scenarios), http://www.cisco.com.by.com/en/US/prod/collateral/switches/ps5718/ps12686/deployment_guide_c07-727067.html#wp9000380
the Cisco Catalyst 3850 Switch can serve as an integrated wireless LAN controller for up to 50 directly attached Cisco access points and 2000 clients per stack. The Cisco Catalyst 3850 Switches can also form the basis of a deployment that supports up to 250 Cisco access points and 16,000 clients. AND, if you have more than 250 APs and/or 16000 clients, it can serve as Mobility Agent and you can still have 5508, WiSM-2 or 5760s as Mobility Controllers, and reach up to enormous numbers like 72000 Access Points and over 1 million wireless devices supported with this architecture.
The comparison between FlexConnect APs in the Campus and the Converged Access model is a great one, but, due to the size of the FlexConnect Groups, and the unavailability of L3 roaming for locally switched wlans, you cannot deploy a campus with this design. As a result, a deployment like that one with Converged Access will add much less additional management overhead than the FlexConnect local switching one. Eventually, when you are refreshing the Switching infrastructure, the configuration of the equipments for Wired and Wireless will be much more streamlined than a deployment of the switching infrastructure independently from the Wireless infrastructure.
Using the 3650 or 3850s offer many benefits in a campus deployment, including the Visibility of both the wired and wireless traffics, often from the same users who either plug in their laptops or use the same devices wirelessly. It also provides a relief of the datacenter links by optimizing the datapath, for wired and wireless Multicast for instance, or also to the Internet, not having to go back all the way to the datacenter encapsulated and leave it again to reach the Internet Gateway, which doesn't reside in the same network block most of the time.
Quite a few other benefits can be mentioned, like the more advanced, hierarchical QoS that can be applied properly at the closest point of access into the network, both wired and wireless, as well as the same downloadable ACLs for the users who connect sometimes wirelessly, and sometimes through the Ethernet port. All of these benefits may or may not appeal to you and/or apply to your environment, but Cisco is offering you the choice of architecture, and, more importantly, lets you migrate from one to the other easily as any 1600, 2600, 3600 access point bought today can be in Autonomous IOS, FlexConnect, Monitor mode, Local CUWN or Converged Access mode ! And you can buy the 3650/3850 switches today, and deploy wireless whenever you will be ready or whenever you will benefit from Converged Access if you are currently not fully convinced, with just a software activation (and Wireless AP licenses somewhere in the network).
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The APs have to be "locally attached" to the 3650 or the 3850. There is no support for a "L2 hop away" function as you describe it.
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Customers who do not upgrade their switching infrastructure to the 3650 or 3850 at the access will need the 5508 w/ 25 or 50 APs licenses, so this still applies, and, once again, this is an architectural choice, as I have seen customers with 100's of APs and very very few clients/traffic, and customers with too few APs and a lot of clients with very high volumes of traffic. The first type would probably still prefer to have the CUWN centralized deployment, whereas the second type would have the real choice and is actually moving over to 3850s as we speak.
Some wireless features, like the ones for Service Provider WiFi deployments, are different between 5508/WiSM-2 and 5760/3650/3850. Generally, the 3.3.0SE IOS features (available in October 2013) can be considered on-par with 7.4 AireOS wireless features.
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Everything is integrated into the same IOS config, for Wired and Wireless features, as there is one UADP ASIC that handles wireless and wired termination and switching with 20Gbps performance. In a 48 ports switch, you can terminate and switch 40 Gbps of wireless traffic, and in a stack of up to 9 switches, you will be able to terminate and switch up to 480 Gbps of traffic (the capacity of StackWise).
Regards,
Flavien.
With Flavien Richard
