Gigabit Ethernet, what speed should it be really?

[bigmike82]

"cat6 is not capable of handling gigabyte traffic. u need fiber for it."
Erm, no? Try again. 1000Base-T is a standard for Cat5, Cat5e AND Cat6.

Hell, Cat6 is even capable of 10Gig speeds.

[sfwdiy]

Those are first generation SATA drives, not exactly fast. You should upgrade to SATA-II (3 Gb/s) or SATA-III (6 Gb/s). Your drives probably don't even support NCQ. You should also make sure you're running them in AHCI mode and not IDE emulated mode. The setting for this is in your BIOS, however if it is not already set to AHCI you'll have to reinstall your OS when you change it.

Good link on native command queueing. I learn something new every day.

--B

[JDay]

Also, you mentioned your router and ethernet cards, what about your modem? Is it gigabit capable?

That doesn't matter, he's not going to get gigabit internet speeds. The ports on the switch should auto sense the ethernet speed of the modem and set it accordingly.

[JDay]

cat6 is not capable of handling gigabyte traffic. u need fiber for it.
check the listing below

HSDPA (cat.6) conversion chart

What does this have to do with HSDPA (3G Data)? Category 6 cable can handle up to 10 Gbit/sec.

http://en.wikipedia.org/wiki/Cat_6#Category_6a

Category 6 cable, commonly referred to as Cat-6, is a cable standard for Gigabit Ethernet and other network protocols that are backward compatible with the Category 5/5e and Category 3 cable standards. Compared with Cat-5 and Cat-5e, Cat-6 features more stringent specifications for crosstalk and system noise. The cable standard provides performance of up to 250 MHz and is suitable for 10BASE-T, 100BASE-TX (Fast Ethernet), 1000BASE-T / 1000BASE-TX (Gigabit Ethernet) and 10GBASE-T (10-Gigabit Ethernet). Category 6 cable has a reduced maximum length when used for 10GBASE-T; Category 6a cable, or Augmented Category 6, is characterized to 500 MHz and has improved alien crosstalk characteristics, allowing 10GBASE-T to be run for the same distance as previous protocols. Category 6 cable can be identified by the printing on the side of the cable sheath.[1]

[jmlivingston]

I just bought a second computer, both of my machines have Gigabit network adapters. So I went and bought a 5 port gigabit switch and a pair of CAT6 cables to see what kind of transfer speeds I could get. I am only getting 11MB/s when transferring files. If I multiply by 8, this is only 88Mb/s, less than a 10/100 100Megabit connection. So what gives?

What are your ports set at for speed and duplex?

Many SOHO grade switches aren't truly capable of handling gigabit line rates. You may very well be seeing constraints on memory too, even if you don't see physical memory go to 100% there may be artificial constraints by the OS or the NIC drivers on how much memory that a network transfer may be assigned. Windows desktop operating systems are also notoriously slow at large/bulk data transfers.

In the real world you'll rarely see true 100% sustained utilization on a gigabit ethernet network, my experience has been that it generally tops out about 92-96% and that's even on big Cisco gear (i.e. Cat 6509s). If you're running TCP traffic don't forget to calculate in latency and TCP-window-size. High speed TCP data transfers are hard to sustain when there's any latency involved.

As others have already said, gigabit will run just fine on Cat5e cabling and does not need Cat6.

John

[JDay]

Windows desktop operating systems are also notoriously slow at large/bulk data transfers.

That issue was fixed back in Vista SP1, I haven't noticed any network performance issues with Windows 7.

[nick]

I just bought a second computer, both of my machines have Gigabit network adapters. So I went and bought a 5 port gigabit switch and a pair of CAT6 cables to see what kind of transfer speeds I could get. I am only getting 11MB/s when transferring files. If I multiply by 8, this is only 88Mb/s, less than a 10/100 connection. So what gives?

There're many other factors affecting the actual transfer. First of all, make sure the link you're getting is actually 1Gbps. Secondly, the switch may not be powerful enough to give you the transfer rate you're looking for. The TCP/IP stack in your OS many not be too efficient. The hardware on both ends might be affecting it. You might have some other activity going on that affects it (say, something else uses the hard drive extensively on either end, the desktop firewalls on both ends affect it, etc.). Your cables may be way too long. You might have some external factor, such as EMI, affecting the transmission. You may have faulty NICs.

Once verifying that the hardware is what it should be, I'd check for retransmissions and for unrelated activity on both ends. I'd also reset the TCP/IP stack, especially if you're using Windows. A bunch of stuff you install add to it, to the point that it becomes really inefficient.

This is just something to start with.

[nick]

Never mind, looks like the drive on the other machine was the issue. It helps reading the threat first

[brianinca]

>>>
OK, I did a copy on the other machine and that is the problem, its only 11MB/s write speed.
>>>

That drive is likely in the process of dying. When you get a huge reduction in read/write performance, the cause is frequently the drive being ready to kick the bucket. The system may still boot and finally get going, but it will go TU soon enough. Drives are cheap, swap and clone it back.

As for SATA performance, I built up a SuperMicro server for my office back in '06, 8xSATA hotswap drives on the not-very-spendy MCP550Pro chipset from Nvidia, with first-gen 420GB WDC RE's in a RAID 1+0 config. I had two older servers I was consolidating, and saw sustained 58 MB/sec writes to that array copying both servers simultaneously.

On the other hand, contemporary Dell 2600's with 3xSCSI 10K rpm drives in a RAID5 array struggled to get 25 MB/sec, so lots of factors go into network performance.

It should be no problem these days to see 90+ MB/sec across the wire with DECENT quality inexpensive switches, RAID controllers, GB NICs and magnetic SATA drives.

Regards,
Brian in CA

[jmlivingston]

That issue was fixed back in Vista SP1, I haven't noticed any network performance issues with Windows 7.

That's good to know. We're still a WinXP shop, getting ready to begin rolling out Win7 this month. I've had some test systems cross my desk mostly for testing wireless and vpn compatibility but that's it. While I have a Vista system here at home, I just don't have any needs for high-bandwidth transfers to see how it performs.

[virulosity]

>>>
OK, I did a copy on the other machine and that is the problem, its only 11MB/s write speed.
>>>

That drive is likely in the process of dying. When you get a huge reduction in read/write performance, the cause is frequently the drive being ready to kick the bucket.

Well that is the new computer! I think the problem is that its a notebook HD, the computer I got is a lenovo q150. Also, its running XP SP3, so there may be some inefficiency there as mentioned before.

[brianinca]

>>>
Well that is the new computer! I think the problem is that its a notebook HD, the computer I got is a lenovo q150. Also, its running XP SP3, so there may be some inefficiency there as mentioned before.
>>>>

No way. Something is wrong. How are you measuring your read/write performance?

Regards,
Brian in CA

[danito]

When troubleshooting I would check the easy stuff first, speed AND duplex should be hard set to 1000/full. It is not really good practice to use the AUTO detect settings on the NIC. But the OP does touch on a intesting subject. I use IPERF for bandwidth testing and I have a never seen a windows machine that even comes close to actual gb though put. I suspect this might have something to do with an IPV4 convention.

[jmlivingston]

Don't set the duplex to "Full" unless you can do it on both sides of a link. Setting one side to full and leaving the other at auto may cause a mismatch which will significantly degrade performance.

When running iperf to test max performance, are you running this as TCP or UDP traffic? If it's TCP then sliding-window will cause the session to peak at just over 80% utilization if there's even 1ms of round-trip latency.

[danito]

When running iperf to test max performance, are you running this as TCP or UDP traffic? If it's TCP then sliding-window will cause the session to peak at just over 80% utilization if there's even 1ms of round-trip latency.