Gigabit Ethernet? where's the speed?

[PDonut]

Hey all, just a quick question..

Im running a desktop and a laptop connected to each other, both with gigabit ethernet, via a cross-over cable which says "verified for gigabit ethernet".
I'm not really sure how this should be working but if i transfer a whole lot of files from one comp to the other and watch the network utilization screen in task manager it only shows about 15% average utilization.

Why the hell is it so low? Isn't there some way to increase this?
Tnx

 

[Rkootknir]

How fast are your hard drives? While the theoretical maximum for gigabit ethernet is 1000Mb\s / 8 = 125MB\s there aren't a lot of drives that can manage that.

Most ATA drives can transfer at about 40MB\s IIRC (might be different, haven't taken a look at performance recently), the SATA ones should get about the same as the limiting factor is the drive speed and not the interface.

If you try to transfer a lot of files in different "queues", ie more than one copying dialog you're also not helping as the drive has to thrash around to write the different segments.

 

[PDonut]

I see...

So computers are actually only worth about 20% of what u pay for them cause all the "Amazing Features" are made comletely useless by everthing else in it.... Beautifull

 

[me]

The limiting factor may be one or both of the NICs. Not all gigabit ethernet NICs will reach the theoretical maximum speed. In fact AFAIK many don't get anywhere near it.

 

[PDonut]

sorry, but i have no idea what u just said NIC?

 

[|tera|]

Network Interface Card, your network card, or built in LAN controller

 

[ap0c]

There are quite a few settings you will need to change to get faster Gigabit speeds - just google it, there are quite a few articles.

Copying between 2 pc's using RAID, over gigabit a speed of approx 40MB/Sec. That was without a 'certified' cable

 

[thed33p]

I agree with Rkootknir

I'm betting you'll find that the notebook has a 4200 RPM drive - in which casa u won't get anywhere near gigabit. replace with a 7200 and it will be stax better.....

 

[Juggy]

I agree with Rkootknir

I'm betting you'll find that the notebook has a 4200 RPM drive - in which casa u won't get anywhere near gigabit. replace with a 7200 and it will be stax better.....

Exactly what I was going to say.

The access speed and seek times on standard laptop drives is terrible. That will be the definite bottle neck.

The only place where the GB ethernet really helps is when you open files off of a network and they load straight into memory.

 

[Obelix]

And if youre using windows, it aint gonna drive the link to its max anyway.

 

[thisgeek]

If you link two gigabit NIC's via a crossover cable, you'll get MAX 100Mbit. You need to use a standard patch cable to link Gigabit NIC's back to back to get gigabit speeds.

 

[pip]

I see...

So computers are actually only worth about 20% of what u pay for them cause all the "Amazing Features" are made comletely useless by everthing else in it.... Beautifull

Yup! It amazes me how so many people go for processor/graphics/RAM speed when the machine bottlenecks elsewhere, typically on the hard drives. One needs some nice speedy 15000rpm SCSI drives to make a really decent machine!

 

[me]

If you link two gigabit NIC's via a crossover cable, you'll get MAX 100Mbit. You need to use a standard patch cable to link Gigabit NIC's back to back to get gigabit speeds.

Why?

 

[Roman4604]

Why?

Gigabit Ethernet requires all 4 pairs in a utp cable. Some older crossover cables may only have 2 pairs crossed, since that was all that was required for Fast Ethernet.

Most newer crossover cables have all 4 pairs crossed, however crossovers are not that important these days as most gigabit (& fast) ethernet adapters have auto crossover detection built-in.

 

[James]

Gbe was never made for general LAN's and has I think that it is more of a marketing gimick. Gbe was intended for use as an uplink or backbone connecting to one or more switch's together. This is because of limiting factors such as slow HDD speed combined with a slow BUS. I think they would preform better on PCIe but we will have to wait and see. I read a guide once and to achieve max speed which was by no means 1Gb/s was to run PCIe NIC's and a very large RAM drive to act as a buffer between the HDD.

 

[Roman4604]

Gbe was never made for general LAN's and has I think that it is more of a marketing gimick.

In real-world usage, I see 2-2.5 times higher throughput using Gigabit (compared to Fast). Granted nowhere near advertised, but still worthy of usage.

 

[James]

In real-world usage, I see 2-2.5 times higher throughput using Gigabit (compared to Fast). Granted nowhere near advertised, but still worthy of usage.

Indeed, it is the same as SATA2 3Gb/s you can never use it.

 

[Juggy]

The only place I see gigabit working is on servers that have multiple connections to them. File servers, mail servers, web servers etc.

One client machine wont max out a GB connection on a server, you'll need multiple client machines to do that and that's what GB ethernet was made for.

 

[fcollingwood]

Im running a desktop and a laptop connected to each other, both with gigabit ethernet, via a cross-over cable which says "verified for gigabit ethernet".

Mate, get your money back for the cable. If you're going to link two 1000BT NICs you need to use a straight through cable.

Gigabit Ethernet requires all 4 pairs in a utp cable. Some older crossover cables may only have 2 pairs crossed, since that was all that was required for Fast Ethernet.

Most newer crossover cables have all 4 pairs crossed, however crossovers are not that important these days as most gigabit (& fast) ethernet adapters have auto crossover detection built-in.

Close, but no cigar.

Here's the REAL reason why you use a straight through Cat5e (or Cat6) patch cable to connect two 1000BT NICs back to back:

100BT uses two pairs, this is correct. One pair is used to transmit, the other pair is used to recieve, thus to link two 100BT NICs you need to crossover the pairs so that the TX pair on one side connects to the RX pair on the other. The TX pair are pins 1 & 2, the RX pair are pins 3 & 6, therefore a 100BT crossover cable would only require the following:
1 - 3
2 - 6
3 - 1
6 - 2

1000BT uses four pairs, that is also correct. However, 1000BT has no concept of TX and RX pairs. Instead, 1000BT transmits and recieves on each pair, using differential filtering to ensure that the near-end RX circuitry ignores the signal produced by the near-end TX circuitry. Thus you require a straight through connection for each of the pairs.

The pairs are defined as
Pins 1 & 2 - Bi-directional pair A
Pins 3 & 6 - Bi-directional pair B
Pins 4 & 5 - Bi-directional pair C
Pins 7 & 8 - Bi-directional pair D

It is completly incorrect to say that most 1000BT NICs have auto crossover detection built in. In fact, none do, as the concept of crossover is not required in 1000BT. Due to the nature of the beast, all 1000BT connections are straight through.

If you'd like to speed up transfer, you can also enable jumbo frames on both NICs. Just ensure that the frame size is set identically on both NICs, otherwise there will be no communication between them at all.