pinging my ipad - i think there's a problem?

[kevbo]

I've been noticing some serious lagging when streaming from Air Video onto my iPad. I decided to ping it in Windows and stumbled upon this. This type of ping is completely unacceptable.. I am literally less than a foot from my router. If I let it go for a couple of minutes, it will time out (it did once in the image as you can see). There's a pattern - it goes from ~25ms to 120+ms every couple of seconds. Of course, it should be <1ms at all times. What the heck?

To put this into context, I just upgraded the firmware on my router and then changed the band to "g only." I never pinged it before, although I was still having streaming trouble. Can anyone else do the same and compare? (Edit: As in ping your iPad, not do stuff with your router)

 

[kheldour]

What router brand?

And possibly it will be fixed with Apple's Wifi upgrade later this quarter.

 

[dennis]

... Of course, it should be <1ms at all times. What the heck?

Was your Windows machine on wireless also during your ping test?

You also need to send a few dozen pings to the router itself so you have something to compare.

 

[NumbLock]

Outstanding info Kevbo! Dennis is right, tho. Ping your router and PC/Mac for comparison.

 

[dennis]

More info for your reference. Here's a ping test from my iMac to my wireless router. The iMac is on 802.11n (Wireless-N) in this scenario. The round trip times vary from just a hair less than 1ms to over 12ms and everywhere in between.


Last login: Sat May 15 17:24:10 on ttys000
iMac:~ Dennis$ ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1): 56 data bytes
64 bytes from 192.168.1.1: icmp_seq=0 ttl=64 time=2.894 ms
64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=1.632 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=1.019 ms
64 bytes from 192.168.1.1: icmp_seq=3 ttl=64 time=1.919 ms
64 bytes from 192.168.1.1: icmp_seq=4 ttl=64 time=1.573 ms
64 bytes from 192.168.1.1: icmp_seq=5 ttl=64 time=2.247 ms
64 bytes from 192.168.1.1: icmp_seq=6 ttl=64 time=0.952 ms
64 bytes from 192.168.1.1: icmp_seq=7 ttl=64 time=12.539 ms
64 bytes from 192.168.1.1: icmp_seq=8 ttl=64 time=1.371 ms
64 bytes from 192.168.1.1: icmp_seq=9 ttl=64 time=4.073 ms
64 bytes from 192.168.1.1: icmp_seq=10 ttl=64 time=0.976 ms
64 bytes from 192.168.1.1: icmp_seq=11 ttl=64 time=1.308 ms
64 bytes from 192.168.1.1: icmp_seq=12 ttl=64 time=0.977 ms
64 bytes from 192.168.1.1: icmp_seq=13 ttl=64 time=0.992 ms
64 bytes from 192.168.1.1: icmp_seq=14 ttl=64 time=1.345 ms
64 bytes from 192.168.1.1: icmp_seq=15 ttl=64 time=0.961 ms
64 bytes from 192.168.1.1: icmp_seq=16 ttl=64 time=1.136 ms
64 bytes from 192.168.1.1: icmp_seq=17 ttl=64 time=0.997 ms
64 bytes from 192.168.1.1: icmp_seq=18 ttl=64 time=0.966 ms
64 bytes from 192.168.1.1: icmp_seq=19 ttl=64 time=0.947 ms
64 bytes from 192.168.1.1: icmp_seq=20 ttl=64 time=2.670 ms
64 bytes from 192.168.1.1: icmp_seq=21 ttl=64 time=1.300 ms
64 bytes from 192.168.1.1: icmp_seq=22 ttl=64 time=0.960 ms
64 bytes from 192.168.1.1: icmp_seq=23 ttl=64 time=1.053 ms
64 bytes from 192.168.1.1: icmp_seq=24 ttl=64 time=1.232 ms
64 bytes from 192.168.1.1: icmp_seq=25 ttl=64 time=7.273 ms
64 bytes from 192.168.1.1: icmp_seq=26 ttl=64 time=3.601 ms
64 bytes from 192.168.1.1: icmp_seq=27 ttl=64 time=0.962 ms
64 bytes from 192.168.1.1: icmp_seq=28 ttl=64 time=1.014 ms
64 bytes from 192.168.1.1: icmp_seq=29 ttl=64 time=1.726 ms
64 bytes from 192.168.1.1: icmp_seq=30 ttl=64 time=0.990 ms
64 bytes from 192.168.1.1: icmp_seq=31 ttl=64 time=1.768 ms
^C
--- 192.168.1.1 ping statistics ---
32 packets transmitted, 32 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 0.947/2.043/12.539/2.271 ms
iMac:~ Dennis$

 

[Sonny Burnett]

This is more a function of the router than anything else. Do you have the ability to adjust the spanning tree protocol on it?

 

[kevbo]

Yeah.. I pinged my router from my Windows PC right after i did that and it was always <1ms. This was via Ethernet though. I'll have to wait until today to do tests on a wireless laptop.

The router is a Netgear. When i first got it, I had a Linksys WRT54G and it didn't seem to have the issue.. But i also didn't have the random disconnecting/disconnecting while idle that I do with this router. I cant rule out the possibility that it's another issue, yet.. But I don't think this router is faulty.

As you probably know, pinging other devices on the network should result in anywhere from 1-5ms (as per Dennis' result) . 30ms is what my ping to Google.com is, 3000 miles away, for comparison.

So PC > router is ruled out. Ill try laptop > router and then PC > laptop.

Is anyone else having trouble with AirVideo?

And i have no idea what spanning tree protocol is.

 

[kevbo]

i have many perplexing reports. some point to it being an issue with the battery of all mobile devices. i tested many. ill post up SSs after work and report my findings later, as i need to get to bed.

 

[kevbo]

No graphs or anything yet.. I've been busy.

Basically what I found was that, at least on my network, both my MacBook and Alienware laptop have similar patterns when UNPLUGGED from their AC adapters. When plugged in, it goes down to 1ms. It must be a power saving feature. But even when unplugged, if one is using WiFi (ie downloading a YouTube video), it again goes down to 1-4ms. Same happens with the iPad, unless the transfer is being done over LAN. When streaming an Air Video, the iPad maintains the 25ms to 100ms loop, sometimes dropping completely.

This is where my knowledge ends. Why don't LAN transfers trigger the iPad to turn off the power saving feature? Is this why it keeps disconnecting me?

Count me down for for having DHCP issues too.