I recently picked up a used gigabit Airport Extreme (APX) and was hoping it would offer some nice features over my Linksys wrt54g. I share my iTunes library between two Macs (iMac and Mac Mini). I had no problems (buffering, dropouts) over my network (wired) with iTunes streaming content from the Mini to the iMac with the Linksys. Today when I was trying to do the same with the macs networked thru the APX it would drop audio for 10 seconds or so at least 2 to 3 times during a song. It seemed like a buffering issue because the song would pick back up where it left off. This is a surprise to me given it's a gigabit router and I'm on a wired network. Not sure what to do now. Is there someway I can diagnose the issue?

-EJ

When the APX works, it works well. I get 915 Mb/s between two minis. Are you using CAT6 cable? Shouldn't have to for short runs. The Airport Utility Advanced tab has a button for Logs and Statistics, and you could look there for unusual events. Funny, I can't find any Statistics on mine. The APX always likes a reset, but mine is usually locked up tight when that happens. That cheap old WRT56G is a surprisingly good router and access point.

EJ, your problem likely isn't a speed problem per se, it's a setup, configuration or hardware problem. Wireless "g" iTunes library sharing of apple lossless files works just fine--so you shouldn't be experiencing any problem with "n" or gigabit.

Did you try sharing using wireless instead of wired? Do you see exactly the same erratic behavior? Also, make sure you can rule out that Spotlight was indexing something or that Time Machine was running at the time.

Where is your iTunes library--on an internal boot drive or on an external drive attached to a Mac?

Take iTunes out of the equation for the moment: when you try a straight file transfer between the two Macs of something large, like say a 7GB ripped VIDEO_TS, how long does it take?

Under System Preferences > Network > Ethernet what does it say? Is this still "Automatic" for both Macs or have you manually changed anything here previously, perhaps in an attempt to get jumbo frame transfers enabled?

This is a surprise to me given it's a gigabit router and I'm on a wired network.

Is there anything else on the network or at the time being is it just the new basestation and the two Macs?

Is there someway I can diagnose the issue?

You should know plenty of folks have had problems with the gigabit Airport extreme, especially w/ dropped wireless connections and NAT port-forwarding. Have you done software update in a while? There have recently been updates to both Airport Utility and to basestation firmware. Why not update both, then do a hard reset and then let the configuration utility walk you through set up again?

There are a couple of other things you could check, too, like in iTunes and Network Utility, but do the software update/hard reset first. If you called Applecare, that's what they'd tell you to do. This shouldn't come into play, but there's also a streaming buffer size in iTunes preferences--what's that set to? And you should probably open up Network Utility > Info just to make sure both Macs are being detected as gigabit (1 Gb.)

I get 915 Mb/s between two minis.
How do I check/view transfer speed?

Are you using CAT6 cable?
Well I have a long run of Cat5e going to the mini maybe that's the culprit. For some reason I thought it would be able to handle gigabit.

That cheap old WRT56G is a surprisingly good router and access point.
Best computer related $70 I've ever spent. Had it over 2 year with no issues ever. I'm glad I only paid $90 for the APX. I'd be quite disappointed if I paid full retail for it. I wanted it mostly for printer sharing and air disk functions though. Which work fine...



EJ, your problem likely isn't a speed problem per se, it's a setup, configuration or hardware problem.
Yep, that's why I posted the question. Thanks for the detailed reply BTW.

Wireless "g" iTunes library sharing of apple lossless files works just fine--so you shouldn't be experiencing any problem with "n" or gigabit.
Pretty much what I figured thus my disappointment/surprise.

Did you try sharing using wireless instead of wired? Do you see exactly the same erratic behavior?
Haven't tested it yet. Figured it wouldn't make a difference. I'll check it out though.

Also, make sure you can rule out that Spotlight was indexing something or that Time Machine was running at the time.
Neither were running at the time I checked. Although I think the mini was seeding a bit torrent file that I forgot about.

Where is your iTunes library--on an internal boot drive or on an external drive attached to a Mac?
External connected to the Mini (usb 2). I share the iTunes library via an alias path that allows the iMac to read the library as if it was local. iMac has drive mounted via direct file sharing.

Take iTunes out of the equation for the moment: when you try a straight file transfer between the two Macs of something large, like say a 7GB ripped VIDEO_TS, how long does it take?
Haven't tried. Will do. What kind of time should it be?

Under System Preferences > Network > Ethernet what does it say?
Both are set to automatic.

Is there anything else on the network or at the time being is it just the new basestation and the two Macs?
I have a Powerbook that connects wirelessly but it was not in use at the time.

Have you done software update in a while? There have recently been updates to both Airport Utility and to basestation firmware. Why not update both, then do a hard reset and then let the configuration utility walk you through set up again?
Yeah yesterday I read that there was a new update. I haven't had a chance to run it yet since this issue started. I will do so.

This shouldn't come into play, but there's also a streaming buffer size in iTunes preferences--what's that set to?
Haven't checked. Not sure it it would matter since I connected directly to the iTunes library via either machine instead of using iTunes filesharing capabilities?

And you should probably open up Network Utility > Info just to make sure both Macs are being detected as gigabit (1 Gb.)
Mini is showing 1GB, iMac 100mb. How do I change it?

-EJ

Eric, I just read your reply but don't have time right now to get into it, it seems you're making things a little more complicated for yourself than it needs to be wrt iTunes sharing. So reduce that complication: Set the iTunes apps on both Macs to share libraries, then open both iTunes apps, and on the iMac "share" the Mac mini iTunes library from within iTunes itself. Start playing something, do you get the same erratic behavior when you stream over your network but within iTunes?

A few quick thoughts:

Although I think the mini was seeding a bit torrent file that I forgot about.

Be careful with this, perhaps open Activity Monitor and check CPU utilization, some BT software can take over a Mac and slow everything down network-wise.

Check transfer speed w/ Activity Monitor, and Cat5e is perfectly fine.

Mini is showing 1GB, iMac 100mb. How do I change it?

System preferences > Network > Ethernet > Automatic/Configure manually/Advanced is where you can look at and tweak specific settings.

The reason you might want to double-check by going wireless is that's independent of ethernet--and it might help you narrow down where your problem lies if you observe x behavior over ethernet but not over wireless.

when you try a straight file transfer between the two Macs of something large, like say a 7GB ripped VIDEO_TS, how long does it take?

Haven't tried. Will do. What kind of time should it be?

If a 7-8GB files takes 3-4 minutes, that's at least decent for Mac to Mac over gigabit.

Assuming you:

1) do have the Extreme set up properly and updated, and 2) that both Macs are seeing each other as gigabit devices and 3) that you're getting reasonable speeds for a file transfer that doesn't involve iTunes, then how you have this set up:

External connected to the Mini (usb 2). I share the iTunes library via an alias path that allows the iMac to read the library as if it was local. iMac has drive mounted via direct file sharing.

is likely problematic. That's why I wanted you just to quickly test share the iTunes library on the Mini to the iMac using the built-in Bonjour iTunes sharing. While you're at it, get on the network with your Powerbook, open iTunes, and stream from the Mini iTunes library--do you have the same erratic pauses and drops?

How do I check/view transfer speed?
-EJ

Google iperf. This is a command line program which will test network performance without involving disks or applications. On one end, run iperf -s; on the other end run iperf -c <ip addr>. On the client end (-c) additional command line parameters will set buffer size, length of transfer, and several TCP parameters.

I'm a bottom up guy for testing.

chefklc,

Ok. I ran all of the updaters.

Something I just learned is that my iMac (G5) is showing its age and is only equipped with 10/100BASE-T Ethernet capability. Also I can't test the iMac wireless because it doesn't have an airport card (purchased before they came standard.)

I tested songs and video via iTunes bonjour sharing wired ethernet. There were no problems. Even my ancient 800mhz powerbook played nicely over wireless.

Transfer time of a 8gb file from the mini to the G5 iMac was 12min. I also tested the same file on a brand new Intel iMac I have here temporarily. The time from mini was 6min. (gigabit hardwired).

I also retested via library sharing (my way) and it only had the pausing issue a couple of times over several songs which is much less than before. So maybe the bit torrent was bogging things down.

Not sure what I want to do. iTunes sharing is okay but the reason I originally set it up the other way (library sharing) was because I could make changes/add/delete from either machine and iTunes wouldn't have to always be running on both machines. I was hoping I could run it that way from a shared drive connected to the Airport Extreme (quasi nas) but something tells me that not going to work very well...

Thanks again for your help.

-EJ

Having monitored this exchange, it seems pretty clear to me that your gigabit file transfer speed issues are not being caused by the Airport Extreme, but rather by the 10/100 Ethernet in the old iMac. Also, installing a Cat 6 wired backbone between routers, switches and the cable or DSL modem should always be your first choice when building a gigabit network. Try and limit the wireless connectivity for the laptops and iPhones that really need it.

Cat 5e cabling works pretty well for Gigabit Ethernet, but you won't see the highest performance that you'd get with Cat 6 cabling. I also isolated segments of our home network into zones, using Netgear Gigabit switches. With these switches, we have Ethernet to the home entertainment center in the den, my office, and my significant other's office. Two zones are Cat 6. The third zone (which cannot easily be rewired) is old Cat 5 (not 5e), so at some point in the future, we'll probably have to rely on 802.11n for that space. Right now though, it is very slow compared to the other network segments, even if a gigabit machine is hard-wired to it.

Finally, don't forget this: the spindle speed and memory cache on the two hard disks affect file transfer reads/writes as well.

Having monitored this exchange, it seems pretty clear to me that your gigabit file transfer speed issues are not being caused by the Airport Extreme, but rather by the 10/100 Ethernet in the old iMac. Yeah that's the conclusion I've also come to. I didn't even realize that my iMac wasn't gigabit until I looked up the specs for it last night. Apparently 1000 became standard on the next gen. Oh well...

Cat 5e cabling works pretty well for Gigabit Ethernet, but you won't see the highest performance that you'd get with Cat 6 cabling. Would it make any difference/help to run Cat 6 between the APX and the iMac (even thought it not gigabit)?

I'm going to go ahead and replace the Cat 5 with Cat 6 between the APX and the mini...

Thanks for your input.

-EJ

Something I just learned is that my iMac (G5) is showing its age and is only equipped with 10/100BASE-T Ethernet capability.

I tested songs and video via iTunes bonjour sharing wired ethernet. There were no problems. Even my ancient 800mhz powerbook played nicely over wireless.

Transfer time of a 8gb file from the mini to the G5 iMac was 12min. I also tested the same file on a brand new Intel iMac I have here temporarily. The time from mini was 6min. (gigabit hardwired).

OK--so you've moved this forward pretty significantly, EJ, you proved "regular" iTunes library sharing works both wired and wireless without any of the drops you were initially experiencing and that's a good sign. Just to give you a point of comparison, I moved an 8GB file between two gigabit Macs over my network (through a gigabit switch) and it took 3 minutes exactly. Activity monitor showed a peak transfer rate of 58 MB/s. That's about the transfer speed I usually get and it makes a huge difference versus 100 "fast ethernet." The sending Mac was my fastest Mac, a 1.83 core duo Macbook with a very fast boot drive inside (the 200GB 7200RPM Hitachi) that I keep relatively empty--that Mac is the hub of my home theater ops.

Like Geo said, there are gonna be times that gigabit speed gets throttled down, and one them can be you're writing to or from drives that just aren't that fast, also drives slow down as they fill up, and some connection types slow your gigabit speeds down. For instance, did you move that 8GB test file over your network from the Mini's USB external? That could explain why it took 6 minutes, especially if both that drive and the Intel iMac drive were more than half full. Just to test, I moved that same 8GB file from a USB external this time, from the Macbook to the same destination Mac, and it took 3:50 minutes.

Now, I don't have a lot of experience dealing with mixed 100 and 1Gb devices on an Airport extreme network--the one brief time I had a Mac without gigabit I didn't have any problems, because the gigabit switch I have seems to auto-sense perfectly--but I still think part of your trouble-shooting has to focus on your Extreme configuration, how it's assigning DHCP addresses, what the ethernet settings are on your two Macs and lastly, just how you have that external USB drive set up to be mounted and shared and written to by the iMac. (I can't let that go, sorry.)

I haven't paid much attention to it, since we've been an all gigabit house for a few years now, but I'd be willing to bet you aren't the first new "n" Airport extreme user to have some difficulty mixing both gigabit and fast ethernet Macs on their network. So dig for those threads.

By the way, do you have an "n" basestation with gigabit? The first models didn't have gigabit ports, just 100BaseT. There's a remote chance this is part of the problem if your gigabit Mac mini was configured manually rather than automatically, and if it isn't trying to send 1500 byte frames (as it should, even with built-in gigabit.)

the reason I originally set it up the other way (library sharing) was because I could make changes/add/delete from either machine and iTunes wouldn't have to always be running on both machines.

Understood. But that Mini would still be turned on, and not allowed to asleep, right? So whether the iTunes app was open or closed wouldn't really impact much. I totally understand from the metadata and coverflow standpoint why you'd want something more than the built-in library sharing, though.

Because of my personal inexperience, there's still something about the way you're trying to manage a single iTunes library over USB with two different Macs that I think still needs to be nailed down, and ruled out as a cause for those drops. Circumventing iTunes isn't something I'm expert at, either, since I tend to be perfectly happy playing by the iTunes rules rather than try to defeat them, but I did bookmark a thread about it a while ago:

http://www.macworld.com/article/58571/2007/06/sharingituneslibrary.html

I also retested via library sharing (my way) and it only had the pausing issue a couple of times over several songs which is much less than before. So maybe the bit torrent was bogging things down.

Well, Azureus in particular can really be a Mac system hog, but your G5 iMac should still be able to have a couple of torrents going with Azureus, have that USB network volume mounted, and be playing back video content from it with no problem--let alone just audio content. I have an old single 1GHz G4 in use that does that, and more, fairly routinely, though it is gigabit. The pauses and drops tell you the problem is still there.

I was hoping I could run it that way from a shared drive connected to the Airport Extreme (quasi nas) but something tells me that not going to work very well...

I wouldn't be so sure, plenty of folks are reporting success sharing their iTunes library via Air Disk and USB after this latest round of updates.

If you're not using Cat5e already, you should be. If you can get Cat6 at close to the same price as Cat5e, by all means do.

For instance, did you move that 8GB test file over your network from the Mini's USB external?
Yeah that was from/to the external.

That could explain why it took 6 minutes, especially if both that drive and the Intel iMac drive were more than half full. mini external is over half full. Intel iMac is mostly empty. As it's a brand new machine.

... and lastly, just how you have that external USB drive set up to be mounted and shared and written to by the iMac. (I can't let that go, sorry.)
Agreed. I do think it's not the most ideal way to go about it. But it worked quite well with my older router so I figured it would be a mostly seamless transition to the APX...


By the way, do you have an "n" basestation with gigabit? The first models didn't have gigabit ports, just 100BaseT.
It's definitely the newer version. Says so on the box.


There's a remote chance this is part of the problem if your gigabit Mac mini was configured manually rather than automatically, and if it isn't trying to send 1500 byte frames (as it should, even with built-in gigabit.)

Pretty sure it's automatic. I didn't have to set anything and the setting in the Network control panel is showing GB.


Understood. But that Mini would still be turned on, and not allowed to asleep, right? True but the issue for me is more that you have to have one main machine for iTunes use and the other essentially just becomes a "slave". It's also a bit of a system resource issue because I use the mini as a HTPC and it's my DVR too. Running Eye TV (DVR) and iTunes together tends to bog things down so I prefer not to if I can.[/QUOTE]


Because of my personal inexperience, there's still something about the way you're trying to manage a single iTunes library over USB with two different Macs that I think still needs to be nailed down, and ruled out as a cause for those drops. Circumventing iTunes isn't something I'm expert at, either, since I tend to be perfectly happy playing by the iTunes rules rather than try to defeat them, but I did bookmark a thread about it a while ago:

http://www.macworld.com/article/58571/2007/06/sharingituneslibrary.html This is pretty much the way I have mine setup. it's just I added one more step by having the iTunes Library on an external drive.


Well, Azureus in particular can really be a Mac system hog, but your G5 iMac should still be able to have a couple of torrents going with Azureus, have that USB network volume mounted, and be playing back video content from it with no problem--let alone just audio content. I have an old single 1GHz G4 in use that does that, and more, fairly routinely, though it is gigabit. The pauses and drops tell you the problem is still there.
Agreed. FWTW - I use BitRocket ...


I wouldn't be so sure, plenty of folks are reporting success sharing their iTunes library via Air Disk and USB after this latest round of updates. I'm going to attempt it. Probably after I get some Cat 6 installed.


If you're not using Cat5e already, you should be. If you can get Cat6 at close to the same price as Cat5e, by all means do. I have 5e... See above.

Just wanted to say thanks again for your help. I know it takes time to answer this stuff and I do appreciate it.

-EJ