Re: Flow label - the problem

[Erik Nordmark <erik.nordmark@sun.com>]

Iljitsch van Beijnum wrote:
> On 21-apr-2005, at 16:00, Brian E Carpenter wrote:
>
> > > You still need to work your way through each packet to see if  there  
> > > is a header, so it's still bad even if the header isn't  there...
>
>
> > Er, every node has to step through all Next Headers anyway, whether or
> > not there is an extra header there.
>
>
> Yes, but not necessarily at this point. Presumably, the shim address  
> remapping will happen early in the processing of a packet, while  
> scanning the full list of extension headers happens much later.

Can you explain why such (undesired from a performance perspective) type 
of behavior would be required?

AFAIK it is sufficient for the implementation to step through the 
extension headers, and when and if it finds a shim6 extension header, it 
would lookup the shim6 context state, and remap the IP address fields to 
the ULIDs that are contained in that context.

Thus when there is no shim6 extension header (because the communication 
hasn't been rehomed to different locators yet, or the peer doesn't 
support shim6), there is no effect in the code path.

   Erik