GigaBit Ethernet to the Desktop - Challenges

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Challenges

It can be readily seen that connecting a GigaBit Ethernet to a desktop-class computer is not necessarily straightforward. There are several possible roadblocks that may be encountered.

  1. PCI bus bandwidth

    When the PCI bus has devices on it which require significant bus bandwidth, the ability of the GigaBit card to move data across the bus is impaired. In general, desktop class systems with high-bandwidth PCI cards need special attention before a GigaBit Ethernet connection will be helpful.

  2. Memory bandwidth

    When any network I/O is performed, the data usually passes through memory at least four times. This does not include the memory transfers required to perform any special processing actions on the data. In general, a system with either DDR or RAMBUS memory will have adequate memory speed to make use of a GigaBit Ethernet connection.

  3. Processor speed

    The processor performs the TCP/IP encapsulation of the data being transferred. This is not a trivial task, and requires a significant amount of computational performance. Virtually any Pentium 4 or Athlon system should have the computational ability to perform the TCP/IP encapsulation fast enough to get a useful performance improvement from the use of a GigaBit Ethernet connection.

  4. Disk speed

    Most GigaBit transfers would probably be made to/from disk. In order to get a any performance improvement from a GigaBit connection, the disk must be able to transfer more than 10MB/S (approximate speed of 100Mb Ethernet). Unfortunately, a large number of the motherboard chipsets used in desktop class systems are not capable of driving a disk at those speeds. This will be the single most common performance limit, considering today's desktop systems.

    Benchmark testing on various motherboards shows that the IDE bus on most motherboards is only capable of transferring 3MB/S. This is true even when the motherboard has UDMA/100 compliant IDE. This speed is not even adequate to take full advantage of 100Mb Ethernet, much less GigaBit Ethernet. For most desktop systems, an IDE interface card will have to be installed into a PCI slot, in order to get adequate disk throughput. It should be noted that most current disks are capable of transferring 50MB/S.

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