Perhaps renewal of security associations is timing out because of delays caused by buffer bloat in the driver? That might be worth a look. Does latency (measured by a ping) get very high?
Yes it used to happen, I remember seeing ping responses up to 1900ms instead of usual ~22ms. However, today, what I get is just a *skip* of ping sequences until I break (^C) the process requesting to much traffic. For example skipping ping probes from 510 to 523:
64 bytes from x.x.x.x: icmp_seq=509 ttl=56 time=22.900188 ms 64 bytes from x.x.x.x: icmp_seq=524 ttl=56 time=22.311495 ms uname -a:NetBSD Host-001 7.99.19 NetBSD 7.99.19 (GENERIC.201507090800Z) #0: Thu Jul 9 08:50:21 UTC 2015 builds%b45.netbsd.org@localhost:/home/builds/ab/HEAD/amd64/201507090800Z-obj/home/source/ab/HEAD/src/sys/arch/amd64/compile/GENERIC amd64
When I break the pkg_add process fetching the binary from a near mirror, the ping probes now resume! So the WPA supplicant seems to be rather more self-healing in -current. Are there actually changes since 7.0_RC1 and current 2015-07-09? As far as I can remember this didn't happen before so I can only assume it's related to my userland upgrade. For the pings being skipped instead of getting high response time, however, I don't know.
Thanks