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    SubjectRe: Slow start -- Linux vs. NT -- it's time to acknowledge the problem!
    On Fri, 30 Nov 2001, Jessica Blank wrote:

    > Hello esteemed kernel hackers:
    > As you doubtless know, NT and BSD both have a broken slow-start
    > implementation. As you may not know, when you try having a Linux box
    > co-exist on a network with a Windows box, this seems to cause the Windows
    > box to CROWD OUT the Linux box on the network.
    > There is a fix to Solaris for this-- or a "workaround", I should
    > say:

    > THERE IS NO FIX TO LINUX FOR THIS. At least, not as far as I could
    > find-- and I just got done Web-searching for a solid 15 minutes, finding
    > MULTIPLE references to the Solaris workaround in the process.

    I seriouly doubt that your problem has anything to do with Linux, but
    rather that the NT machines are set up to use Netbeui which puts
    NETBIOS packets into broadcast packets. This means that all the data
    to/from the M$ file-servers ends up being handled by your Ethernet board
    and driver, then dumped onto the floor.

    A properly implimented IP Network minimizes the amount of broadcast
    traffic. M$ tends to maximize it. Such a typical mess looks like

    # tcpdump -n
    10:47:03.349550 > udp 215
    10:47:03.349607 > udp 216
    10:47:03.350618 > udp 221
    10:47:03.351338 > udp 213
    10:47:03.352340 > udp 211
    10:47:03.352973 > udp 212
    10:47:03.356839 > udp 215
    10:47:03.359190 > udp 217
    10:47:03.360571 > udp 208
    10:47:03.361669 > udp 215
    10:47:03.361938 > udp 214
    10:47:03.363611 > udp 213

    Here, data is being sent from a server, port 138
    to a broadcast address,, port 138. Port 138 is
    NETBIOS Datagram. So, all this data gets sent to every machine
    on the LAN. It generates an interrupt, the driver gets the data
    and passes it on. The IP stack looks at it and says "It ain't for
    me...", and throws it away. This all takes CPU cycles that
    Microsoft is stealing from you. The solution is to fire your
    M$ administrator. Failing that, you need to get the fastest
    Ethernet card, with a good fast driver. This allows the M$ data
    to be thrown away without using too much of your CPU time.

    IP filtering in your machine doesn't do any good. It just adds
    CPU cycles. The broadcast packets aren't for your machine anyway
    so they are being rejected without any additional filter.

    Dick Johnson

    Penguin : Linux version 2.4.1 on an i686 machine (799.53 BogoMips).

    I was going to compile a list of innovations that could be
    attributed to Microsoft. Once I realized that Ctrl-Alt-Del
    was handled in the BIOS, I found that there aren't any.

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