From mboxrd@z Thu Jan  1 00:00:00 1970
From: erik quanstrom <quanstro@quanstro.net>
Date: Sat,  9 May 2015 07:43:37 -0700
To: 9fans@9fans.net
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Subject: Re: [9fans] fossil+venti performance question
Topicbox-Message-UUID: 504c7994-ead9-11e9-9d60-3106f5b1d025

> Looking at the first few bytes in each dir of the initial TCP
> handshake (with tcpdump) I see:
>
>         0x0000:  4500 0030 24da 0000  <= from plan9 to freebsd
>
>         0x0000:  4500 0030 d249 4000  <= from freebsd to plan9
>
> Looks like FreeBSD always sets the DF (don't fragment) bit
> (0x40 in byte 6), while plan9 doesn't (byte 6 is 0x00).
>
> May be plan9 should set the DF (don't fragment) bit in the IP
> header and try to do path MTU discovery? Either by default or
> under some ctl option.

easy enough until one encounters devices that don't send icmp
responses because it's not implemented, or somehow considered
"secure" that way.

- erik