Ethernet slow one way?

Z

zaxcom

Registered
I have three Macs connected together using a linksys router. Mac 1 and Mac 2 talk to each other just fine and exchange files at about 82Mbps. But Mac 3 has an issue. It is an older 333iMac. When I send files to it I get a consistent 62Mbps, which is fine considering the 5400RPM drive and 66Mhz bus.

But when I try to get files from the iMac it creeps. Maybe 5 or 6Mbps and lots of stalls and hesitation.

I tried using a different port on the router and had no effect. The 100Mbps light on the router is on for all ports.

All three machines are running OSX 10.2.6

Any ideas?

Thanks

Zax
 
It could be a number of things. Check the ethernet cable. It could be damaged or old - old things do break down and run slow (hehehe). A new ethernet - or a even shorter length may improve things.

Second idea could be that the older Mac is just slower in processing, you may need more memory installed to speed things up. Or you just need to run a Disk Utility on the machine. Drive 10 is a good one. Do not use Norton on OS X.
 
Well, it has definitly nothing to do with your cable. There is no seperated line for upload and download. Fullduplex is using the same line just different timing for up and download. And since you can send files to that one with 62Mbps...
And obviously your system can handle the fast data-transfer. It's a weird problem. Is there any way to check out some kind of advanced options of network-devices and compare? Options like duplex, protocol, timing... I know those from pc.
And one more idea. If you have still some more ports free on your router, try another plug. in worst case I would try to connect two systems directly (without router) and see, how your rates look like. If they are fine, it has something to do with your router.
Let us know
 
I have three Macs connected together using a linksys router. Mac 1 and Mac 2 talk to each other just fine and exchange files at about 82Mbps. But Mac 3 has an issue. It is an older 333iMac. When I send files to it I get a consistent 62Mbps, which is fine considering the 5400RPM drive and 66Mhz bus.

But when I try to get files from the iMac it creeps. Maybe 5 or 6Mbps and lots of stalls and hesitation.

I tried using a different port on the router and had no effect. The 100Mbps light on the router is on for all ports.

All three machines are running OSX 10.2.6

Any ideas?

Thanks

Zax
 
If you run "netstat -s | grep retransmitted" in the iMac, do you see a large number of packets retransmitted? If you check immediately before starting a copy and again as soon as it ends, oes the number increase quite a bit? How much?

Rip
 
Otherwise, can you give more details? Any idea how you're transferring files? AFP? CIFS? What happens if you try FTP?
 
Yes, when I try to send the file from the imac to the other machines I get a very high number of retransmitted packets. But when I put the files onto the imac i do not get that problem.

I am connecting using file sharing. Appletalk is turned off.

I also tried using FTP and while it was much slower than file sharing, the results were the same. Up loads very fast, no packets problems. But downloads off the imac were very slow and lots of packets retransmits.
 
Actually, in 10/100/1000baseT Ethernet, transmit and receive use different lines, even in half-duplex mode. Ethernet simply uses old-fashioned CS/CDMA to detect if collisions occurred, even if there's only two devices - an Ethernet NIC and a switch. This is all weird legacy stuff =)
 
Have you tried a completely different patch cable on this iMac, not just a different hub node? It's possible there is a flaky ethernet port on the logic board

How about transferring this thread to hardware (or deleting one)? there are 2 separate threads on this identical problem and this member, the other is already in hardware
 
I ran a test on the cable. I have a very comprhensive cable tester made by Microtest, called a Pentascanner. It reports that all of the lines are fine and there are no problems with the cat5 in any way.

Swapping out would be hard too. it is a 82 foot run through the walls of the house.
 
Data is getting lost coming FROM the iMac to your systems. Since data copies "fine" between your two other systems, this has something to do with your iMac.

It's most likely one of three things:

1) You have a faulty cable with a poor (or poorly twisted) TX line. Try replacing with another, good, Cat 5 cable. Perhaps try a known working one from one of your other systems.
2) NIC going bad in the iMac. Least likely, and not much you can do except get another logic board or NIC.
3) The switch ports of your Linksys router are set to auto-negotiate speed and duplex, while your NIC in your iMac is set to 100/full duplex. As a result, the switch cannot negotiate settings with your iMac, and falls back to 100/half, causing a duplex mismatch. Problem is, this way, packets usually get lost in the OTHER direction, but it still wouldn't be healthy.

Look to see how the iMac is set - run "ifconfig en0" and see what it says next to "media" (not "supported media"). It may make sense to force it to auto-negotiate (Apple calls this "autoselect", which is a bit misleading)

Rip
 
Would putting Airport into the iMac be viable? You wouldn't have to put the other 2 computers on Airport if they work well together, but you may want to get around the Ethernet problem with the iMac.
 
I ran ifconfig and it said it was in full duplex/100. The router also says full duples/100.

The cable tester said the cable was fine. So it may be the NIC. Just to confirm though i am going to make up a new cable and just run it through the house on the floor and see what happens. Either way i am really hosed. A new logic board is expnsive and pulling a new cat5 through the walls will be a major hassle.
 
It reports that all of the lines are fine and there are no problems with the cat5 in any way.
Click to expand...

Still, if you're out of other options, try hooking the iMac up to another, good cable and port (I know it's a pain, but I've seen too many cable testers lie to think that's the end of the story).

Rip

*Edit: I'm not intentionally repeating everything that everyone says, it just takes me a really long time to reply because I'm doing it between commercials and apparently not bothering to hit "refresh" =)
 
I have eliminated the router from the equation. I hooked the imac cable directly to the G4 and still had the same problem. I used a crossover cable in between by the way.
 
Now, were they both set to autoselect, both set to full duplex, or one set one way, and one set another? Are you sure you didn't get rid of one problem and introduce another?
 
All still set to 100/full duplex. I came up with a solution if it is the cable. Since there are two unused pairs in the Cat5 cable I am going to remake the connectors and use another pair.
 
You must log in or register to reply here.
Back
Top