Subject: Re: Intel i82547 performance problems in wm(4)
To: None <>
From: Matthias Scheler <>
List: tech-net
Date: 07/16/2004 11:58:54
On Fri, Jul 16, 2004 at 11:29:18AM +0200, Mipam wrote:
> Suppose I've got a card which support tcp offloading. It'll be enabled by
> default, ...

No, it won't, at least not with NetBSD.

> however, when i run a firewall which manipulates several fields in the ip
> and tcp  header i do not wish the card to perform offloading.

Why not? The card will calculate the correct checksum whether the firewall
manipulated the packet or not. The firewall only has to cope with the
fact that it will see outgoing packets with incorrect checksums.

> Is it allowed to disable this by somethig like
> ifconfig wm0 -ip4csum -tcp4csum -udp4csum link0 media autoselect
> or isnt it?

Yes, but it's not necessary. Offloading will be disabled by default unless
you manually disable it.

	Kind regards

Matthias Scheler