Subject: Re: wm* hardware assist breaking gif tunnels
To: None <>
From: David Young <>
List: tech-net
Date: 09/06/2007 15:41:19
On Thu, Sep 06, 2007 at 05:43:00PM +0000, John Klos wrote:
> Any suggestions?

Taking a guess, maybe wm h/w sets received packets' embedded checksums
to 0 (or anything not equal to the actual checksum) when h/w assist
is active?  Maybe wm h/w expects for an embedded checksum to be 0 in
transmitted packets, also?  I have seen wm(4) lose in a bridge until I
turned off h/w checksum; it may have been for that very reason.
And I see this comment in ip_output(),

                 * Always initialize the sum to 0!  Some HW assisted
                 * checksumming requires this.
                ip->ip_sum = 0;


David Young             OJC Technologies      Urbana, IL * (217) 278-3933 ext 24