-----Original Message-----
From: Robert E. Seastrom <rs(a)bifrost.seastrom.com>
To: peterf(a)microsoft.com <peterf(a)microsoft.com>
Cc: nanog(a)merit.edu <nanog(a)merit.edu>
Date: Wednesday, February 04, 1998 1:40 PM
Subject: Re: MTU of the Internet?
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>I have no idea where they came up with this "576 internally" nonsense.
>Generally whenever one runs into that number it is as a result of
>creaky old software that expects to be running over milnet or arpanet.
>
IPX used 576 forever whenever you had to cross IPX "subnets". The reason
was simple. They were lazy. 576 was the least common denominator between
Ethernet, TR, and _Arcnet_
Large IPX (LIPX) allowed them to do basically what IP calls Path MTU
discovery. Only took them a day short of forever to figure out how to do
it.
>Are Microsoft stacks known to be broken in the packet
>fragmentation/reassembly department? Or are just acknowledging
>deficiencies in their path mtu discovery code by setting the MSS in
>the basement? I knew they had problems with window length (this from
>my friends with long fat pipes)...
>
With all the paranoids trying to block all ICMP, not just ICMP_ECHO, doesn't
that essentially break PMTUD. 576 may not be efficient, but its probably
the safest to assume.
