Subject: Re: TCP_MSS to 1460 in tcp.h or /etc/netstart?
To: None <tech-net@NetBSD.ORG>
From: Wolfgang Rupprecht <>
List: tech-net
Date: 10/25/1997 09:42:30 (Erik E. Fair  , Time Keeper) writes:
> 1. change sys/netinet/tcp.h TCP_MSS to 1460

I've run this way for 5 years now.  First under SunOS, lately under
NetBSD.  In practice it works just fine.

It would be great if I didn't have to run a sed script on tcp.h before
each build.

> The Ethernet MTU has been the standard MTU for DS0 (64Kb/s) and T1 leased
> lines in cisco equipment for a long time, and they're still the majority of
> the backbone last I checked. MTU for FDDI and T3 is even higher.

I know that FDDI is usually run with 4kB packets.  Out of curiosity,
what do folks use on T3?

And I almost dread posting this, each time I mention a more modern
MTU/MSS I get tons of mail from both sides of the cluefullness scale.

(It seems to be a common misconseption for folks setting up their
SLIP/PPP links to request a really small MTU in an attempt to get a
better interactive response.  In the absense of TOS queuing, I don't
see how it matters much if an interactive packet is stuck behind 3 500
byte packets or one 1500 byte one.)