CAT 5 maximum theoretical transfer rate under Windows 7 Ultimate x64

[TheDarkKnight]

Hi,

I am currently transferring 30+ gigabytes of files through my home network from one computer to another. I have a gigabit router. One computer is connected to the router through a CAT5 cable and the other computer is connected to the router through a CAT6 cable. So, I know that the transfer rate will only be as fast as the CAT5. The maximum transfer speed has been pretty constant at around 11.0 MB/second using Windows 7 GUI cut'n'paste operations from one folder to another.

According to my mathematics as to what the maximum theoretical transfer speed across CAT5 would be, I am thinking it should be around 119 MB/second. Here are my calculations:
CAT-5 maximum theoretical transfer rate: 1000Mbps or 1Gbps
1Gbps/8 = 125,000,000 bytes/second
125,000,000/1,048,576 = ~119.21 MB/second

So the theoretical maximum transfer speed between two CAT5 connections is ~119.21 MB/scond and I am getting 11.0 MB/second.

Are my calculations correct and how can I speed future transfers up. Does robocopy work better/faster?

Thanks for reading and all help and suggestions.

 

[Fardringle]

Good quality CAT5 cable can actually work for a gigabit connection if the cable length is not too long. However, 11 MB/s is just about right for 100mbps ethernet so it sounds to me like you aren't actually connecting at gigabit speed. Check the status of the network connection on both machines in the "Network and Sharing Center" to verify the connection speed that Windows is reporting.

 

[imagoon]

There can be a ton of reason for performance being less than theoretical. #1 are you sure the NICs are actually synced at 1gbps? Are you seeing error frames accumulating? Did you build these cables or are they machine built? Can the drives keeps up? Are there a ton of small files? Is the source drive well defragmented? Is the switch showing 1 gig connections?

I find that slow speeds a lot of times are cabling issues. Esp for people that insist on building their own cables. If the physical layer is fine it can be anything from lots of small files (ton of files system overhead) to badly fragmented disks (disk IO issues.)

--edit--

I have also had Windows 7 running in VMware downloading data from another SAN over 4 x 1gig connections at over 280meg/sec so I know 7 doesn't natively limit the network cards at all.

 

[JackMDS]

Sloppy Giga network comprised of Windows computer usually yield about 30 to MB/sec. functional transfer (B=Byte).

Good optimized network should yield 60-80 MB/sec. functional transfer.

 

[TheDarkKnight]

I didn't make my cables. I either bought them from someone or they were given to me by TimeWarner.

The local connection does show it at 100.0 Mbps. How do I change that to 1000 Mbps? I went into the network adapter settings and it shows the "speed and duplex" option set to "auto-negotiation". So, for whatever reason, its only connecting at 100.0 Mbps. I wonder if my CAT-5 cable is really CAT-5. I'll have to check that next.

 

[BrightCandle]

Could be your router isn't 1 gbit/s. Its a common money saving tactic to use 100mbit/s ports in a router since the ongoing connection isn't going to be very fast.

 

[ericloewe]

You need Cat. 5e cable for Gigabit for short distances, Cat. 6 for up to 100m.
Gigabit ethernet usually provides almost 100% of its stated throughput (minus a little bit for overhead), so you should have values close to the theoretical 119 MB/s, assuming everything can handle it (disks, NICs, switches and routers).

 

[TheDarkKnight]

Could be your router isn't 1 gbit/s. Its a common money saving tactic to use 100mbit/s ports in a router since the ongoing connection isn't going to be very fast.

It is a gigabit router. It's the D-Link DIR-655. I also checked both integrated network controllers. They are both gigabit nics. Its most likely as ericlowe is stating that one of the older CAT-5 cables is the problem. It's problem not a CAT-5E so I'm just going to replace the cable with a CAT-6 and be done with it.

I happen to be one of the lucky people living in KC, MO. So when Google fiber is installed in my area I'll be needing the CAT-6. But they will probably provide that anyway.

 

[imagoon]

Does the CAT5 wire have all 8 wires in it? Certain cheap ones are only 2 pair (4 wires,) 4 wires = auto 100meg at best. Replace the problem cable and see what happens.

 

[KentState]

Does the CAT5 wire have all 8 wires in it? Certain cheap ones are only 2 pair (4 wires,) 4 wires = auto 100meg at best. Replace the problem cable and see what happens.

That's what I was thinking.

 

[robmurphy]

For Gigabit Ethernet Cat5E is fine up to the 100M max for Ethernet. Over 100M is out of the standard. Cat6 is no quicker than Cat5E on a Gigabit network.

I've seen quite a few 2 pair Cat5 patch leads supplied with routers over the last few years. Easy to check just look at the ends. On most cables you can see the cores used, so its simple to check if only 2 pairs (or 4 cores) have been used.

Rob