Subject: Re: Path MTU discovery
To: Wolfgang Rupprecht <>
From: Perry E. Metzger <>
List: tech-net
Date: 07/15/1997 21:22:10
Wolfgang Rupprecht writes:
> I've used BSDI 2.1 for a year now and the MTU path discovery code,
> without fail, will "discover" 1500 byte MTU, 1460 byte tcp_mss.  This
> is the same answer as my SunOS machine that has been running a fixed
> 1460 byte tcp_mss for > 5 years now.
> So unless one is on a network where the MTU is larger than 1500 (FDDI,
> 100b-tx w. hacked packet size etc.)  there is very little interesting
> for the MTU discovery code to discover.  The answer is almost
> certainly "1500".

But it won't be in the future. Our job is *not* to produce code that
works for a little while, but code that lasts for a long while.