In message <v04020a53b34934f7370b@[209.157.85.34]>"Erik E. Fair" writes
>Given that the IMPs (excuse me, PSNs) are only found on MILNET these days,
>and Cisco routers with their default leased line MTU that match Ethernet
>MTU are ubiquitous, plus there's Ethernet and Fast Ethernet everywhere,
>optimizing for handling Ethernet MTU seems a very good idea...

Yep, that kind of reasoning is why the few ports that didn't aleardy
have MCLBYTES > Ethernet frame size got MCLBYTES bumped.

The point of leaving the option around is to leave open the choice of
optimizing for an MTU of around ~4k or ~8k.