AppleTV 2 (black) Ethernet speed between ATV2 and ReadyNAS

Hi guys,

I've trying all sorts of things, searching the net but couldn't find a question this strange problem.

Ever since my ATV2 was crashed (I don't know why it crashed but it crashed over night) and I could not start the AVT2. I had no choice but to try SeaS0nPass to upload the firmware again. Unfortunately, Seas0nPass uploaded the iOS5 onto it. Anyway, I followed the instructions (from this forum) to install XBMC Eden on the ATV2 with iOS5. Everything was fine for a few days and all of a sudden, everything became so slow, XBMC showing "buffering" so often or it became sluggish and caused audio / video out of sync badly.

I've tried everything I've found on this forum (went to the FAQ, read so many topics....) and I have decided to test the network between my ATV2 to the ReadyNAS NV+. What I have is:

- ATV2 plugged to Cat6 Ethernet cable (brand new) to Air Port Extreme (running firmware 7.5.2).
- ReadyNAS NV+ plugged to Cat6 Ethernet cable (also brand new) to the same Air Port Extreme. This ReadyNAS is set to 100Mbit Full Duplex.

I've created half a gigabyte file on the ReadyNAS then then SSH into AVT2. From ATV2, I've tried to ftp to the NAS:

ftp> get halfgig /dev/null
200 PORT command successful
150 Opening BINARY mode data connection for halfgig (524124160 bytes)
226 Transfer complete
524124160 bytes received in 278 seconds (1887516 bytes/s)

Now, 1887516 bytes/s is 1.89 Mbps. How could it be?

I used my laptop also plugged in the same Air Port Extreme with the same Ethernet cable and the same ftp test resulted: 85.53 Mbps

I know ATV2 has 100Mbit ethernet and why it is so slow? I think this is the culprit causing stuttering and buffering quite often.

Is there anyone experienced the same problem? Is there any suggestion to fix this strange problem?

Thanks guys.

(2012-05-03 12:13)sydneydownunder Wrote:  I used my laptop also plugged in the same Air Port Extreme with the same Ethernet cable and the same ftp test resulted: 85.53 Mbps

To confirm, you mean from NAS to Laptop?

If so, can you do the same test, from NAS to AppleTV, but with the AppleTV connected wirelessly to the Airport.

i'm also having the same issue with using ethernet connection, wireless seems to be alittle better but not much

Hi Cranial,

Yes, I did the same test between my laptop and NAS using the same ethernet cable and Air Port Extreme. This was to verify if the Cat6 ethernet cable was good or bad and the Air Port Express was good or bad.

Last night I have also tried to use the crossed cable between ATV2 and the NAS directly (did not use the Air Port Extreme) and the result was not any better.

Before that, I have also tried the wireless (802.3n at 5hz). My Air Port Express reported that AVT2 was connected at 65mbit under excellent condition but the ftp result was even worse. Playing an MKV H.264 codec was stuttering all the way .

I have then tried to apt-get update / upgrade and plugged the ATV2 back to the Air Port Extreme with ethernet cable and the situation was not improved.

After checking things out, I've found that there were 2 kernel parameters:
net.inet.tcp.delayed_ack=1
net.inet.tcp.mssdflt=1440

in /etc/systl.conf which I have tried from this thread: http://forum.xbmc.org/showthread.php?pid...3pid959135

I have reversed them back to:
net.inet.tcp.delayed_ack=0
net.inet.tcp.mssdflt=1500 (because I am using Ethernet)

then the situation improved. The file transfered with 1464773 bytes per second (roughly 11.718184 mbps), which is about 10 times faster.

But... 11.78 mbps is still way too slow on a 100Mbit Ethernet line. That what buzzed me

I've mucked around with the kernel parameters on the ATV2 and found:

kern.ipc.maxsockbuf: 1048576 (1Mb). This value can't be higher, what a bummer .

net.inet.tcp.sendspace: 131072 (128K). This value is too small. I pumped it up to 524288 (512K).

net.inet.tcp.recvspace: 131072 (128K). This value is too small. I pumped it up to 524288 (512K).

After that, I've done the FTP test again and the result was 1742230 bytes per second (roughly 13.93784 Mbps), another 2Mbit improved.

Perhaps the physical memory on ATV2 is limited (200Mb) and therefore, the kernel has hard limit of certain kernel parameter value.

I suspect that the Darwin kernel running on ATV2 has other restrictions too.

5.8MB/s from macbook on wifi to atv2 on wired using scp. That's bytes not bits. No tweaks

Mine 4.1MB/s from macbook (Lion) on 5hz channel wifi to ATV2 on wired using scp, roughly 32.8 megabits per second. So, the inbound from outside to AVT2 is quite OK.

Now, with both ATV2 and NAS are on wired and hooked to the same Air Port Extreme:

- From AVT2, scp the same file from NAS to ATV2 (pull) achieved the rate: 790.0KB/s, roughly 6.32 megabits per seconds.

- From NAS, scp the same file from NAS to ATV2 (push) achieved the rate: 810.5KB/s, roughly 6.484 megabits per seconds.

Something is wrong between ATV2 and NAS for sure .

Uh oh....

Apple-TV:/private/var/mobile/Library/Preferences root# tcpdump -i en0 -s0 -w test port 445
tcpdump: listening on en0, link-type EN10MB (Ethernet), capture size 65535 bytes

Ethernet on ATV2 is 10Mbit link?

Is there anything similar to mii-tool or ethtool on ATV2 (running Darwin Apple-TV 11.0.0 Darwin Kernel Version 11.0.0: Wed Feb 1 23:17:16 PST 2012; root:xnu-1878.11.8~1/RELEASE_ARM_S5L8930X AppleTV2,1 arm K66AP Darwin) guys?

Not that i know off.

(2012-05-04 10:21)sydneydownunder Wrote:  Uh oh....

Apple-TV:/private/var/mobile/Library/Preferences root# tcpdump -i en0 -s0 -w test port 445
tcpdump: listening on en0, link-type EN10MB (Ethernet), capture size 65535 bytes

Ethernet on ATV2 is 10Mbit link?

Is there anything similar to mii-tool or ethtool on ATV2 (running Darwin Apple-TV 11.0.0 Darwin Kernel Version 11.0.0: Wed Feb 1 23:17:16 PST 2012; root:xnu-1878.11.8~1/RELEASE_ARM_S5L8930X AppleTV2,1 arm K66AP Darwin) guys?

Interesting. Something screwy with the jailbreak?

*EDIT*

Had a look at mine, (from work, not home for a bit), same output as you:

[quoteATV:~ root# tcpdump -i en0 -s0 -w test port 445
tcpdump: WARNING: en0: no IPv4 address assigned
tcpdump: listening on en0, link-type EN10MB (Ethernet), capture size 65535 bytes[/quote]

but interesting, same output from en1 (mine's running on wifi)

Quote:ATV:~ root# tcpdump -i en1 -s0 -w test port 445
tcpdump: listening on en1, link-type EN10MB (Ethernet), capture size 65535 bytes

Don't really know what to say here?

*EDIT 2*

I think the EN10MB can be ignored, haven't had time to read up on tcpdump, but all references I've seen in a quick google search show EN10MB in the output.