I've been tinkering with the Chicagoland Skydiving Center network in preparation for the 2014 Independence Boogie. This is generally a large event, and this year is no exception:
The vast majority of the people on the network are guests on wifi.
CSC can be broken down into three domains:
- The south building, including the Flight Deck restaurant, pro shop, bathrooms, showers, and team rooms
- The main hangar, which is largely open space but also contains several offices both ground-level and on a mezzanine
- Outdoors, including the CSCity RV park, the courtyard, the loading area, and outdoor dining at Flight Deck
Both the south building and the main hangar are served using three access points. Their locations, frequency assignments, and antenna coverage patterns were carefully chosen to avoid interference and to provide consistently high perforance, especially under load.
The couryard is easy enough to handle with omnis, but CSCity is a problem. Residents expect their cell phones to pick up the CSC wifi inside their trailers – even though trailers are basically Faraday cages. We can serve 5 GHz clients using directional antennas, but 2.4 GHz doesn't give us enough channels to make that a viable option, so we've been running with a single omni.
The last week included four separate projects:
- We upgraded the CSCity mast on the SE corner of the main hangar. This mast provides service using two 14 dBi 5 GHz sector antennas and a 6 dBi 2.4 GHz omni. The antenna configuration did not change, but the radios powering it are improved.
- We upgraded the courtyard mast on the NW corner of the south building. This mast provides service using a 10 dBi 5 GHz omni and a 6 dBi 2.4 GHz omni. As before, same antennas, better radios.
- We added a CSCity North mast with a single 2.4 GHz access point. Channel selection was difficult; with the hangar door open, this AP can see at least one other AP on every frequency. I chose to alias the AP that serves the least traffic with the lowest transmit power, and CCQs remain high. CSCity North is the only AP that is not directly wired to the rest of the network using Ethernet; instead, it's connected via a point-to-multipoint 5 GHz backhaul.
- We renumbered the public VLAN. We have been close to running out of addresses on a single /24; it's now a /22. IPv6 service remains unchanged at a /64, and DHCPv6 prefix delegation lets you request additional routed /63s.
I'm pretty happy with the performance during this event:
The main hangar access point has the highest load (see all those people on the packing mat?) but performance is excellent: 0.1% retransmit rate, 22 mbps throughput, 60 associated stations. Note also this access point is using only 11 dBm EIRP.
Other drop zones (*cough*) have networking poor enough that I bring a 3G hotspot. CSC's network makes me happy to live here full-time.