Take the internet brakes off an iMac

October 10, 2006 4:53 AM

iMac G4 has really slow internet speed, PC on the same network is zippy - how do I track the problem and squish it?

The network is just these two machines: 1 PC (Win2K), 1 iMac (OSX 10.3.9). They both go through a router, however while the PC connects wirelessly, the iMac is plugged straight into the box.

I've got IPNetMonitorX to help me find what's loose, but unfortunately only about bugger all experience in network admin. I've found that pings work across the network, but only sometimes work for targets on the internet... and that's sort of where I get stuck.

The OSX firewall is off, there are no DNS settings on either machine to get confused by (the router handles this), I really can't spot what's amiss - can you help me debug?

posted by NinjaTadpole to computers & internet (16 comments total)

Check to see if IPv6 is enabled (it shouldn't be).
Go to Network>Show:Built-in Ethernet>TCP/IP. Toward the bottom there should be a "Configure IPv6" button. Click that and make sure IPv6 is disabled.

If your service provider isn't supporting IPv6 (and most don't yet), having this enabled can slow your internet access to a crawl.

Also, unless you really, really need it, AppleTalk should be disabled as well. Not that that should affect your internet connection, though.
posted by Thorzdad at 5:04 AM on October 10, 2006 [2 favorites]

IPNetMonitorX probably won't help much because it troubleshoots your connection to the outside world, which (based on your Windows workstation) is working properly.

IPNetTunerX will help you easily tune various TCP parameters on your system, to get the most out of your particular network connection.

A free, but very-limited-scope alternative is Apple Broadband Tuner 1.0, but this is generally only useful for a particular type of network connection. It might be worth trying, in any case, as it is easy enough to uninstall.
posted by Blazecock Pileon at 5:14 AM on October 10, 2006

Ah, IPv6 - now off. Whatta good catch.
Speed is definitely up a notch, thanks Thorzdad. (nice illustration, too - good waiter)

Blazecock, I'll have a go.
posted by NinjaTadpole at 5:26 AM on October 10, 2006

I just disabled IPv6. Wow.
posted by mcwetboy at 6:01 AM on October 10, 2006

IPNetTunerX looks far too small-scale to be the answer - I'm not going to be changing the MTU sizes. This problem has to be a common setup gaffe because I haven't monkeyed with the networking minutiae, which is why the IPv6 shot was so good.

Don't let me stop your ideas though.

Speed is better, but only something like 2/3rds of the Win2k machine's. Any other regular network faux pas?
posted by NinjaTadpole at 6:03 AM on October 10, 2006

What hardware do you have? Could the speed differences be explained that way?

Also, what about RAM? Browsers being used?
posted by Mo Nickels at 6:29 AM on October 10, 2006

Ninja,
Thanks for the compliment!

Other things to look at...
In the same Network control panel...under the Ethernet tab...Is it set to Configure manually or automatically? Default is Automatically. Macs are usually champs at optimizing ethernet speed for the network, but sometimes something trips them up. Try switching to "Manually(Advanced)". Then set the speed to whatever the max is for your router. Probably 100baseTX. Set to full-duplex, too.

You might play with packet size, but I wouldn't bother, really. I'd keep it on Standard.

Also, under the Proxies tab, make sure NO proxies are selected. And under "PPoE" tab, make sure "Connect using PPoE" is NOT selected.

You don't mention what router you are using.
posted by Thorzdad at 6:41 AM on October 10, 2006

Also...Do you happen to be mounting the Mac to the PC? And, if so, you don't happen to have the Mac sharing the PC's internet connection? That would certainly slow it down.

Have you tried taking the PC offline and seeing if that affects the Mac's internet connection?
posted by Thorzdad at 6:52 AM on October 10, 2006

Mo Nickels: 700Mhz G4 with 384MB RAM, 1.8Ghz AMD with 1GB RAM, both running Opera 9.

The same speed problems are apparent running any browser on the iMac, which is why I suspected it was network settings. Opera on the PC runs everything quicker than Firefox and IE, and I (perhaps naively) assumed the same would be true on a Mac. I did think it had 500MB RAM in though, so that does change my expectations a little - perhaps you've got the rest of the diagnosis there.


Thorzdad: yes, it's set to auto, and fiddling seems to have no effect. No proxies, no other connections.
OSX is happy using the newly applied settings without restarts, isn't it? No setting cache?

Both machines run individually through a Netgear DG834G with full firmware patch.



I'm now glumly resigned to it being a hardware limitation, unless anyone's got sparks still left to fly. Running "top" suggests that RAM and VM are working pretty happily (OSX is only supposed to have about 5MB free, right?)
posted by NinjaTadpole at 7:33 AM on October 10, 2006

(and the Mac running solo through the router has no effect on speed)
posted by NinjaTadpole at 7:33 AM on October 10, 2006

Check that your DNS numbers are correct.
posted by kenchie at 7:37 AM on October 10, 2006

DNS settings are all received by the router from the ISP and shared by the connected machines. Neither machine sets its own DNS addresses.
posted by NinjaTadpole at 8:01 AM on October 10, 2006

try these commands in Terminal:

sysctl -w net.inet.tcp.sendspace=65536
sysctl -w net.inet.tcp.recvspace=65536
sysctl -w kern.ipc.maxsockbuf=524288
sysctl -w net.inet.tcp.delayed_ack=0
sysctl -w net.inet.udp.recvspace=73728

These greatly increase the default TCP and UDP buffer sizes and turn off delayed acks.

If this helps, then you can throw it in an AppleScript that runs at startup, or whatever.
posted by kindall at 8:44 AM on October 10, 2006

oh, sorry, you're going to want to throw a "sudo" in front of each of those lines, and you'll need to enter your admin password after the first one.
posted by kindall at 8:45 AM on October 10, 2006

no luck with the parameter changes either, sorry kindall.


As a sideways approach to the problem, the Mac is now running the lightweight Shiira browser, which seems to have hurried things up a bit. It'll do.

Thanks for all the advice.
posted by NinjaTadpole at 3:59 PM on October 10, 2006

No specific knowledge, but I like System Optimizer, which has internet speed-up options along with a bunch of other useful things.
posted by AmbroseChapel at 8:08 PM on October 10, 2006