| (I apologize that this isn’t a programming question. But it does relate to my understanding of networks and Apple network gear…)
I’m trying to diagnose some frustrating connectivity problems between my MBP, my Airport Extreme base station, and my Airport Express. The latter is being used just for AirPlay music streaming, not as a base station in its own right. AirPlay is really, really intermittent; most of the time iTunes can’t connect, and when it does it cuts out after a few seconds.
So in a shell I’m pinging the Airport Express:
$ ping 10.0.1.5 PING 10.0.1.5 (10.0.1.5): 56 data bytes Request timeout for icmp_seq 0 Request timeout for icmp_seq 1 Request timeout for icmp_seq 2 Request timeout for icmp_seq 3 Request timeout for icmp_seq 4 Request timeout for icmp_seq 5 …
And so on, no responses at all. Then 45 seconds later:
… Request timeout for icmp_seq 45 64 bytes from 10.0.1.5: icmp_seq=0 ttl=255 time=46896.140 ms Request timeout for icmp_seq 47 64 bytes from 10.0.1.5: icmp_seq=6 ttl=255 time=42821.925 ms 64 bytes from 10.0.1.5: icmp_seq=7 ttl=255 time=43049.368 ms 64 bytes from 10.0.1.5: icmp_seq=8 ttl=255 time=42086.386 ms 64 bytes from 10.0.1.5: icmp_seq=9 ttl=255 time=41398.708 ms
Something’s been buffering up these ICMP packets (either the pings or the responses) for up to 46 seconds! That seems weird to me; my probably-naive understanding is that IP packets will get dropped on the floor if they can’t be delivered. I think 802.11 makes some attempts to retransmit, but for _45 seconds_?! And ICMP packets of all things — aren’t those used only for ping and traceroute, i.e. to check connectivity? Making aggressive delivery attempts seems counterproductive for those.
—Jens (who just wants to play his damn music, really) |