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Ethernet network speed

By vytenis ·
We have a 10/100 MB/s autosensing hub LAN running Ethernet peer to peer. Computers on the network are Pentium 133 MHz or higher with IDE disk drives and running Win ?98. The hub indicates that communication is occuring at 100 MB/s. The collisions indicator rarely flashes and when it does the 100 MB/s reverts to 10 MB/s momentarily. In timing the transfer of either one large file or a group of files from computer to computer via Window Explorer, I noticed that it takes approximately 14 minutes to transfer 1.5 GB. If each byte is 8 bits then there are 12 Gigabits or 12,000 Megabits. At 100 MB/s this would result in a transfer time of 120 seconds. Why is the transfer slower than expected?

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Ethernet network speed

by brian In reply to Ethernet network speed

You aren't taking into account the extra overhead required. Like headers and other packet information. However, I agree that this would not account for the difference you are seeing. Try the same test to/from other computers to see if you get the same results. You also might want to install a packet sniffer to see exactly what is going on. To look for errors etc. In addition, if you have unneeded protocols installed, that could dirty things up. If you are using NetBEUI, then get rid of the TCP/IP binding to the NIC (if it exists). The same for any other protocols. Just some ideas. Keep in mind also that there is a big difference between a switch and a hub. Hubs generally are 100 Mbit/sec combined, all ports. Higher quality switches,in theory can transfer at 100Mbit/sec, per port. Just some ideas.

Brian

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Ethernet network speed

by vytenis In reply to Ethernet network speed

No unneccesary protocols installed. Transfer speed the same for different computers. I now know the difference between a hub and a switch!

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Ethernet network speed

by dheupel In reply to Ethernet network speed

Answer #1 is correct. You have to take into consideration the number of machines hanging on that segment, in addition to the traffic's overhead. A more realistic test would be to conduct it at night, or some other time where the other workstationson this segment would be turned off. A 10/100 hub or concentrator is shared 10/100 Mbps bandwidth across all ports of the device. A switch is more capable of delivering full bandwidth to each port on the device. With traffic overhead taken into consideration, actual maximum throughput on a 10BaseT segment, for example, would be about 6.4Mbps before the segement was saturated with traffic and near 100% utilization. I did the math too, and my numbers came out a little differently:

1.5 GB =2 to the power of 10, squared, times 100, times 1.5, which = 12,582,912,000 bits.

Divide 12.5Gbps by 1000 to get Mbps = 12,582.912. 840 seconds in 14 minutes, therefore throughput was about 14,979,657 bits/second divided by 8 to calculate for megabytes = 1.8725 MBps. This looks about right for a 100Mbps hub.

Cheers!

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Ethernet network speed

by vytenis In reply to Ethernet network speed
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Ethernet network speed

by vytenis In reply to Ethernet network speed

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