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2 computers on same router, by different speed

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October 11, 2005 4:07:44 AM

I have two computers on the same router. My Comcast advertise a max of 6 mbps. On testing one of my computers I get 5.5 mbps. On my other computer I only get 4.6 mbps. I am using the on board NICs for both computers. I got these numbers based on several runs on several days.

One motherboard is Asus P4T533-c with a built-in Intel pro-100 ve NIC. (5.5 mbps)
The other motherboard is GA-8IHXP 3.0 with a built-in Realtek RTL8139/810x Family Fast Ethernet NIC. (4.6 mbps)

Does anyone have any idea why one computer is faster than the other? I used nyc.speakeasy.net to test the computers. The faster computer is connected to a 50 ft cat 6 cable to the routher. If anything I would think the computer running with a 3 ft cable should be faster. Something has changed, but I don't have a clue to what. I am pretty sure the speeds us to be equal.

Any ideas? Could upgrading the router flash cause a problem?

Any software to fully test the NICs?

Best regards,

Peter

More about : computers router speed

October 11, 2005 1:22:12 PM

You're right, the longer the cable, the longer it takes for the data to get there.


The NICs use different chipsets, so that has a processing factor. The computers aren't identical, so there is that factor. The quality of the cables may even factor in some, the distance can factor in, EMI can factor in, etc.

Depending on hardware configuration and the negotiation of each NIC, the best you could do is set both NICs to 100/full duplex in the NIC properties, then run the test. That will tell you the best possible performance you'll get from either NIC.

Just because they're both 10/100 NICs doesn't mean they both operate at the same level.
October 11, 2005 9:35:32 PM

Thanks for the reply. I need to find sometime to test the NICs properly.

Regards,

Peter
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November 16, 2005 4:52:13 PM

It is more likely that your bandwidth on your Comcast is so variable that it gives you different readings. The bandwidth from Comcast is shared with everyone in your neighborhood, so if there is more traffic at any given time, you will have a decrease in your overall bandwidth.

The wire length inside your house does not matter, nor does your router or nic settings, unless you have old 10 mbit hardware. 100 mbit hardware is more than capable of handling 5.5 mbps. Having wire length of 100 feet would only take a 100 mbit connection down to about 92 mbit.

Try this software to learn more, it has a section for benchmarking your network.

http://www.sisoftware.co.uk/index.html?dir=dload&locati...
November 20, 2005 4:23:08 PM

I really don't think your NIC or cabling has anything to do with it either.

If you want to just test your NIC, download NetCPS to both computers, and transfer 1000MB of data between the two. You'll more then likely get 80Mbps+ transfer.
December 6, 2005 4:59:42 PM

Quote:
The bandwidth from Comcast is shared with everyone in your neighborhood, so if there is more traffic at any given time, you will have a decrease in your overall bandwidth.


This no longer true. Comcast, TimeWarner, Roadrunner, etc have all upgraded their hardware to guarantee a certain degree of bandwidth (close to what they advertise) to every customer. Of course, speeds will still vary on this like line noise and line quality. But the old logic of "the more users, the slower the speed" is simply not true anymore. However, cable is still as you say, a shared network. Read below:

Quote:
Most cable modem systems rely on a shared access platform, much like an office LAN. Because cable modem subscribers share available bandwidth during their sessions, there are concerns that cable modem users will see poor performance as the number of subscribers increases on the network. Common sense dictates that 200 cable data subscribers sharing a 27-Mbps connection would each get only about 135 Kbps of throughput -- virtually the same speed as a 128-Kbps ISDN connection -- right? Not necessarily.

Unlike circuit-switched telephone networks where a caller is allocated a dedicated connection, cable modem users do not occupy a fixed amount of bandwidth during their online session. Instead, they share the network with other active users and use the network's resources only when they actually send or receive data in quick bursts. So instead of 200 cable online users each being allocated 135 Kbps, they are able to grab all the bandwidth available during the millisecond they need to download their data packets -- up to many megabits per second.

If congestion does begin to occur due to high usage, cable operators have the flexibility to add more bandwidth for data services. A cable operator can simply allocate an additional 6 MHz video channel for high-speed data, doubling the downstream bandwidth available to users. Another option for adding bandwidth is to subdivide the physical cable network by running fiber-optic lines deeper into neighborhoods. This reduces the number of homes served by each network segment, and thus, increases the amount of bandwidth available to end users.


From: http://www.cabledigitalnews.com/cmic/cmic1.html

I live in one of the most heavily saturated cable internet city in America, Albuquerque New Mexico (believe it or not). I often get speeds in excess of 6mbps at home and certainly never below it. And I can tell you that nearly all my neighbors have cable internet.

-mpjesse
January 23, 2006 2:21:36 AM

It is possible that the driver for the realtek nic is holding you back or that the tcp/ip parameters on the two systems are different. The first is pretty easy to check by tossing a ten dollar intel 100t nic in the machine with the gigabyte motherboard.
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