North American Network Operators Group

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Re: PC Bozo's World bites again (CNN, too)

  • From: Matt Sommer
  • Date: Tue Jun 02 12:29:30 1998

Does RFC-879 still have any validity?

"      HOSTS MUST NOT SEND DATAGRAMS LARGER THAN 576 OCTETS UNLESS THEY
      HAVE SPECIFIC KNOWLEDGE THAT THE DESTINATION HOST IS PREPARED TO
      ACCEPT LARGER DATAGRAMS.

    This is a long established rule.

    To resolve the ambiguity in the TCP Maximum Segment Size option
    definition the following rule is established:

          THE TCP MAXIMUM SEGMENT SIZE IS THE IP MAXIMUM DATAGRAM SIZE MINUS
           FORTY.
           The default IP Maximum Datagram Size is 576.
           The default TCP Maximum Segment Size is 536.
"



>Michael Dillon <[email protected]> writes:
>
>> I don't think so. They even said in their article that the technical
>> details are based upon this URL
>> http://www.sns-access.com/%7Enetpro/maxmtu.htm
>> and this guy says stuff like:
>>
>>     And, it turns out, depending on how your ISP and other routers
>>     encountered on the Internet handle your TCP/IP requests, that a
MaxMTU
>>     setting of 576, often referred to as the "Internet Standard", will in
>>     many cases avoid the fragmentation of packets of data and the slow
>>     transfer speeds which result.
>
>He used to be one of my users, at two different ISPs, in fact.  I
>had a long drawn out disagreement about how this was wrong, and
>mathematically didn't make any sense.
>
>However, lots of people have confirmed that it really does
>help... which leads me to accept Karl's explanation.
>
>We shouldn't expect anymore from microsoft, really.
>
>Darrell