RE: about the ULID in the TCP checksum

["Henderson, Thomas R" <thomas.r.henderson@boeing.com>]

> -----Original Message-----
> From: Iljitsch van Beijnum [mailto:iljitsch@muada.com] 
> Sent: Monday, January 08, 2007 7:37 AM
> To: Henderson, Thomas R
> Cc: shim6-wg
> Subject: Re: about the ULID in the TCP checksum
> 
> On 4-jan-2007, at 23:39, Henderson, Thomas R wrote:
> 
> >> If this is a problem, it's probably better to adjust the checksum
> >> such that it appears to be correct to a non-shim6 aware observer.
> >> This does have the downside that incorrect address rewriting isn't
> >> detected by the checksum, though.
> 
> > Why not both twiddle the checksum at the shim so that it is 
> aligned  
> > with
> > locators, and de-twiddle when deshimming?
> 
> I think I like this approach better than what's currently in 
> the draft.
> 
> However, it does have a downside: since the checksum is 
> adjusted when  
> doing the shim processing, it's not possible to detect incorrect  
> shimming using the checksum.
> 

What do you mean, "detect incorrect shimming using the checksum"?  Do
you mean context confusion?  I'm not sure it's any worse off.

Tom