Inert Detritus The Internet's dust bunnies

14 February 2010 @ 12am

Briefly: Network Topologies

Things I learned today: network link-layer topology makes a huge difference for wireless.

My file transfers via 802.11n from one laptop to another were pretty slow: max sustained throughput was 3–4 MB/sec. As an experiment in solving unrelated AirPort base station association issues, I plugged one laptop (that’s already wired up to the TV as a media center of sorts) into the base station via GigE. Because the AP no longer has to negotiate with two clients on the same slice of spectrum for network traffic, my inter-machine transfer rate jumped to 15–18 MB/sec.

Note that this only applies when the laptop is associated to the base station that the other client is wired to. Since I have both a Time Capsule and an AirPort Extreme, when the wireless laptop roams to the Time Capsule, its link to the Time Capsule is contending with the Time Capsule <> AirPort Extreme wireless link, and the speed falls off again.

The network layout looks something like this: