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You are here: MacNN Forums > Hardware - Troubleshooting and Discussion > Mac Desktops > Slow network speeds on early 2008 Mac Pro

Slow network speeds on early 2008 Mac Pro
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Oct 10, 2008, 04:50 PM
 
Not sure what has happened, but starting this morning my Mac PRo is just lagging in network performance. I am hard wired into a router, so no Wi-Fi. When I try and transfer files, I see speeds of 40KB/sec, where I used to get 11MB/sec. If I do an internet speed test, I see transfer rates of about 5000kbps, where as I used to see 9500kbps. I've booted into Windows as well, and see the same performance degradation, so it is not a OS X thing.

I checked other computers in my house, and there are no issues. I have also connected a laptop in directly where my MacPro is, and it sees normal performance (fast transfers).

I've tried resetting the SMC and PRAM (according to Apple support documents) to no avail. Anyone have any thoughts?
     
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Oct 10, 2008, 09:14 PM
 
When you connected the laptop in, you used the same ethernet cable I assume?

Can you run an ifconfig -en0 and post the results? It may be an auto-negotiation problem.
     
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Oct 10, 2008, 10:57 PM
 
So even though Apples support website mentions that my Mac Pro doesn't have an SMC reset button on the motherboard, I did see a button that looks an awful lot like one (it is right near the battery). So I pressed that, and now my internet speeds are back up to where they should be (9000kbps).

However, my lan speeds are still really slow. Connecting to another machine using AFP, I get transfer rates of 20KBps still. Other computers on the network have no problem transferring at more normal speeds (11MBps). What could be causing my internet speeds to be fast but my internal network speeds to be slow?


benmac:~ kupan787$ ifconfig en0
en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULT ICAST> mtu 1500
inet6 fe80::21d:4fff:fe46:b0b0%en0 prefixlen 64 scopeid 0x4
inet 192.168.1.201 netmask 0xffffff00 broadcast 192.168.1.255
ether 00:1d:4f:46:b0:b0
media: autoselect (1000baseT <full-duplex,flow-control>) status: active
supported media: autoselect 10baseT/UTP <half-duplex> 10baseT/UTP <full-duplex> 10baseT/UTP <full-duplex,hw-loopback> 10baseT/UTP <full-duplex,flow-control> 100baseTX <half-duplex> 100baseTX <full-duplex> 100baseTX <full-duplex,hw-loopback> 100baseTX <full-duplex,flow-control> 1000baseT <full-duplex> 1000baseT <full-duplex,hw-loopback> 1000baseT <full-duplex,flow-control>
( Last edited by kupan787; Oct 11, 2008 at 02:26 AM. )
     
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Oct 11, 2008, 02:50 AM
 
OK, it seems odd that in the first line of your ifconfig it looks like it's running simplex, whereas the media entry claims to be full-duplex capable. This would affect LAN use more than Internet (assuming you have a typical broadband set-up).

I think you can "force" the interface to full duplex. I'll see if I can find a reference, but feel free to google it while my lazy ass tries to get to it.
     
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Oct 11, 2008, 12:51 PM
 
Originally Posted by dimmer View Post
OK, it seems odd that in the first line of your ifconfig it looks like it's running simplex, whereas the media entry claims to be full-duplex capable. This would affect LAN use more than Internet (assuming you have a typical broadband set-up).

I think you can "force" the interface to full duplex. I'll see if I can find a reference, but feel free to google it while my lazy ass tries to get to it.
Network->Ethernet->Advanced->Ethernet (?)

Here I can manually configure my Speed and Duplex. If I choose "1000baseT" for speed, I have a choice of "full-duplex" or "full-duplex, flow control". I tried both, but didn't see any difference. Would I need to restart my machine between selections?

On a side note, while googling a bit, I did see mention that some others were seeing slow down with AFP when IPv6 was turned off. I just noticed that mine is on, but I have no IP address. I don't use IPv6, but I know that previously it had shown something there. I don't know if this could be of any cause at all either.
     
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Oct 11, 2008, 01:01 PM
 
Sounds like a problem that can be caused by a faulty cable. Have you tried other cables for all machines?
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Oct 11, 2008, 01:12 PM
 
Originally Posted by OreoCookie View Post
Sounds like a problem that can be caused by a faulty cable. Have you tried other cables for all machines?
I've tried another machine on the same cable, and it works fine. When trying another cable with my Mac Pro, I see no change at all.

However, today I am back to slow speeds on the internet and lan with the Mac Pro, while no other computers are effected. I just ran a ping test, and noticed that I am getting 10% packet loss when pinging my router. Using other computers in the house, I don't see this. I'm going to reboot into Windows and see if I get the same packet loss to rule out a software issue.
     
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Oct 11, 2008, 01:25 PM
 
It could be a bad port on the router/switch or on the Mac, too. Have you tried other ports (Mac Pros have two ethernet ports)?
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Oct 11, 2008, 01:40 PM
 
Originally Posted by OreoCookie View Post
It could be a bad port on the router/switch or on the Mac, too. Have you tried other ports (Mac Pros have two ethernet ports)?
I've ruled out a bad port on the router and the switches based on the fact that I can plug other computer in directly to where my Mac Pro is connected, and they work fine. So everything points to the mac Pro as the cause. I've tried both ports on the mac pro, and see no difference, exactly the same behavior out of each. And I just got done booting into Windows, and same deal. Slow internet and dropped packets.

This really sucks, because it is starting to seem more like a hardware issue.
     
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Oct 11, 2008, 11:27 PM
 
If you get the same problem under Bootcamp/Windows then yeah, you' ve pretty much ruled out software issues. And by trying each ethernet port and getting the same results you've eliminated any physical level issues. Sadly, this does look like a hardware problem, that may well require attention from a dealer or Apple Store. Sorry.

Just for shits and giggles, can you link the Mac Pro to another system (directly: with one cable from one to the other) and see if things (file transfers for example) are the same or are they better?

On a LAN, the OS -should- be using IPv6, but IPv6 has Bonjour type auto-addressing built in. Again, I wouldn't think this is a route to your problem as you are seeing the issue under Bootcamp as well.

I'll try to think of other options to troubleshoot (have you ran the Apple Hardware Test application?) -- but it may be easier just to take the thing into a shop (you have AppleCare right?)
( Last edited by dimmer; Oct 11, 2008 at 11:27 PM. Reason: typo!)
     
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Oct 13, 2008, 01:20 PM
 
So, most of the other machines in my house only have 100BaseT ethernet ports. My router is only 100BaseT, but I do have 2 gigabit switches, and an AppleTV (which has gigabit). So far in all my testing with the laptop connected to where my Mac Pro is has been on a a machine with only 100BaseT. So, just to test something, I forced my Mac Pro down to 100BaseT, and wouldn't you know it everything is working great!

So I am starting to think it is not my Mac Pro, but it is the switches in my house. Could they somehow have blown out the ability to connect at gigabit speed?
     
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Oct 14, 2008, 07:18 AM
 
That's one possibility. But I suspects it's the cable: it could be that you aren't using cables made for GBit ethernet: there are three relevant types of cables Category 5, Category 5e and Category 6. Category 5 cables have been designed for 100 MBit connections and although in theory, some GBit adapters are designed to work with Cat5 cables, there are often problems with those cheaper cables. The reason is that there is a lot more interferences, especially interference between different wires (so-called cross-talk). GBit ethernet is a lot more sensitive to that.

Cat5e cables include additional screening compared to Cat5 cables which reduce a specific kind of cross-talk.

Cat6 cables have been designed with GBit ethernet in mind: they are built so that cross-talk is effectively suppressed.

I suspect that your cable isn't up to the job to handle GBit ethernet. That's why it works with other computers which (presumably) use only GBit ethernet. Once you've slowed down your Mac Pro, it works as expected, because with the lower transmission rate, cross-talk and other interference do not interfere with the transmission of the data anymore.
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Oct 14, 2008, 12:29 PM
 
Originally Posted by OreoCookie View Post
That's one possibility. But I suspects it's the cable: it could be that you aren't using cables made for GBit ethernet: there are three relevant types of cables Category 5, Category 5e and Category 6. Category 5 cables have been designed for 100 MBit connections and although in theory, some GBit adapters are designed to work with Cat5 cables, there are often problems with those cheaper cables. The reason is that there is a lot more interferences, especially interference between different wires (so-called cross-talk). GBit ethernet is a lot more sensitive to that.

Cat5e cables include additional screening compared to Cat5 cables which reduce a specific kind of cross-talk.

Cat6 cables have been designed with GBit ethernet in mind: they are built so that cross-talk is effectively suppressed.

I suspect that your cable isn't up to the job to handle GBit ethernet. That's why it works with other computers which (presumably) use only GBit ethernet. Once you've slowed down your Mac Pro, it works as expected, because with the lower transmission rate, cross-talk and other interference do not interfere with the transmission of the data anymore.
Hmm. The problem is I have no idea what the cable in my home walls is. This is a new built home (last year), and the cables are purple (if that means anything). I would assume they are Cat5e, but really I don't know and all documentation I have for the home doesn't list specifics for the cable. I can try replacing all the external cable (that hooks everything into the walls), making sure it is all Cat6.

The odd thing is that all this happened just a couple of days ago, once it really started to cool down temperature wise. Prior to that, my Mac Pro ran with no special modifications, and was transferring over the network at above 100baseT speeds. One of the switches is stored outside (tucked into the phone switch box on the side of the house). The switch is nothing special, just a $50 netgear, so could it be that the cold temp is effecting it?
     
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Oct 14, 2008, 01:31 PM
 
Could be the effect from airconditioning or other electric appliances that create interference. In the worst case, you are limited to 100 MBit ethernet if the problem is the cable in the wall.
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Oct 18, 2008, 02:07 PM
 
I would suspect either the cables or the switch itself. Have you tried rebooting the switch to clear the ARP cache? What's the specific model of the switch?

My folk's home was custom-built last summer, and I suggested they wire it with Cat6. The electrician didn't even have it on hand, and had to special order it which cost about 2x the price of regular Cat5e. My guess is you probably don't have Cat6 unless you requested it.
     
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Oct 24, 2008, 08:24 PM
 
suggested they wire it with Cat6. The electrician didn't even have it on hand

God that brought so many horror stories to mind: in my experience, the single best thing you can do for your network cable infrastructure is keep the electricians as far away from it as possible. That they didn't have Cat6 cable on-hand is a good indicator that they are out of their comfort zone.
     
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Nov 18, 2008, 05:00 PM
 
Originally Posted by kupan787 View Post
Not sure what has happened, but starting this morning my Mac PRo is just lagging in network performance. I am hard wired into a router, so no Wi-Fi. When I try and transfer files, I see speeds of 40KB/sec, where I used to get 11MB/sec.
Was wondering if you had any resolution to this issue?

Where I work, we have 4 new Mac Pros that are having the exact same issue -- very slow network performance.

If I plug any other computer into the same patch cable that they use, the other computers run fine.

If I take the Mac Pros to a different location in the building, they seem to work fine.

Our networking guys had me switch the Mac Pros from autodetect to Gig Full, that fixed the problem for one day (yesterday). A day later, they're slow again. (they're still set for Gig Full)

The networking guys did some sniffs and see lots of re-transmits. They don't think it's cabling because I hauled an iMac over to one of these desks and used the same patch cable going to the Mac Pro, and the iMac was able to quickly copy a file to the network.

I think they want to say that it's the Mac Pros fault, but I think the likelyhood of four of them being bad is pretty low? And like I said, if I take one of the Mac Pros to my desk upstairs (which goes to a different wiring closet), the Mac Pro works fine.

Argh.
     
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Nov 18, 2008, 05:30 PM
 
Have you tried manually setting the networking speed to 100 MBit/s?
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Nov 18, 2008, 10:58 PM
 
Originally Posted by aristobrat View Post
Was wondering if you had any resolution to this issue?

Where I work, we have 4 new Mac Pros that are having the exact same issue -- very slow network performance.

If I plug any other computer into the same patch cable that they use, the other computers run fine.

If I take the Mac Pros to a different location in the building, they seem to work fine.

Our networking guys had me switch the Mac Pros from autodetect to Gig Full, that fixed the problem for one day (yesterday). A day later, they're slow again. (they're still set for Gig Full)

The networking guys did some sniffs and see lots of re-transmits. They don't think it's cabling because I hauled an iMac over to one of these desks and used the same patch cable going to the Mac Pro, and the iMac was able to quickly copy a file to the network.

I think they want to say that it's the Mac Pros fault, but I think the likelyhood of four of them being bad is pretty low? And like I said, if I take one of the Mac Pros to my desk upstairs (which goes to a different wiring closet), the Mac Pro works fine.

Argh.
It turns out for me it was a bad switch. I just went out and upgrade my old lynksys gigabit switch with a netgear one, and now all my machines are operating just fine with autoselect, and they are transmitting at over 100Mbit speeds.

The problem appear to be with the Mac Pro as none of the other machines I had at the time were capable of gigabit. Just recently I got a new Macbook which has gigabit, and with the old switch it wasn't functioning correctly either. I have my switch outdoors, so I'm guessing maybe condensation, or something ruined it from operating at higher speeds.
     
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Nov 19, 2008, 11:08 PM
 
Looks to be a switch issue here as well. The network guys ended up patching the Mac Pros to a wiring closet one floor directly above the switch that these Mac Pros normally use and they've been screaming fast for the last 36 hours. The network guys are going to going to reboot the original switch this weekend and see if that solves the issue.

Thanks everyone for the followups!
     
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Nov 25, 2008, 03:15 AM
 
Alright, I have to ask: WTF did they re-wire rather than rebooting the switch? A single command line input and a 45 second network burp wasn't worth more than a rewiring job AND a subsequent switch reboot? Job security?
     
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Nov 25, 2008, 10:02 AM
 
Their decision to reboot was a direct result of them having rewired first. Before seeing these Macs work on a similar but different switch, they were pretty much saying that the issue was with the Macs themselves, not anything network infrastructure related. The decision of when production equipment can be rebooted (even in a break/fix situation) comes from a special change control group/process that nobody in IT particularly cares for, so that was out of their hands. Oh, the joys of working at a retail company in fourth-quarter.
     
   
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