On Sat, 6 Apr 2013, Roy McMorran wrote:
Thanks for the thoughtful questions David... see below
On 4/6/13 1:37 AM, David Lang wrote:
Other than the fact that your APs lock up, what problem are you trying to
solve?
That's high on the list. Also...
* accommodate more users in larger rooms such as classrooms, auditorium,
conference rooms
* reduce the number of SSIDs; we now have one to six different SSIDs per bldg
** allow roaming without client having to switch SSIDs
* separate guest & student traffic from faculty/staff (eventually...)
* improve coverage & tolerance of interference in certain problematic
locations
* (maybe) add some outdoor APs for special events
* centralize management and logging
Is this a wide-open network (like MIT used to have), is this something for
visiting guests to use, or do you intend for this to be only for your
employees?
It is presently wide open, which is why I haven't chimed in on the
RADIUS-vs.-whatever question much. I'll probably want to segment off a
staff-only SSID at some point but that's likely to be phase 2.
do you have issues with coverage?
Yes in some areas. Many smaller buildings are small single-story wood frame
construction and one AP will cover 2-3 bldgs fine. Larger/newer bldgs are
steel frame and metal deck + concrete & rebar floors, so 1 AP per floor now
and we still have some dead spots, so I think that may have to increase.
how many people do you expect to be using the wireless at any one time?
Typical usage will probably be about 20 per AP. Classrooms could be double
that. Auditorium, maybe up to 100 during certain events.
what are they doing on the wireless? (using SSH to connect to servers is
vastly different than streaming HD video)
Nothing too brutal at the moment. Internet access, email, access to file
servers and application servers. Yep, even some SSH. Yes, probably some
video streaming and I'll wager that will increase with time.
I'm not in a position to re-engineer the whole campus at this time, but I'm
going to have to replace the access points in two of our larger buildings
(they just aren't cutting it) and I hope to select a system I can build on as
we move forward.
take a look at both the paper and the talk that I gave at LISA this year on the
wireless setup that I build for the SCALE conference
https://www.usenix.org/conference/lisa12/building-wireless-network-high-density-users
There's a shorter version of it in this month's ;login as well
In short, I like to go with cheap (i.e. consumer grade) APs because they give me
great flexibility when loaded with openwrt
1. they can be managed with the normal *nix management tools (including logging)
2. since they are cheap, you don't agonize over how many you deploy, if you
think you need a few more, you just put them in place.
3. by picking ones that can run openwrt, you future proof yourself by not
locking yourself into any one vendor's equipment or any one vendor's management.
Yes, it's nicer to have all the APs the same, even with openwrt, but it's like
your linux servers. It's nice when they are all the same, but it's not that much
worse if you have a few different generations of systems where each generation
is a different vendor.
You absolutly do want to use one SSID, not several.
For the staff, you can either add an additional SSID, or you can have the staff
use VPNs to connect from the general use one. There are advantages to both.
David Lang
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