Re: [mpls] Last Call: <draft-ietf-mpls-in-udp-04.txt> (Encapsulating MPLS in UDP) to Proposed Standard

[Joe Touch <[e-mail]>]

On 1/27/2014 10:48 AM, joel jaeggli wrote:
> On 1/27/14, 8:48 AM, Joe Touch wrote:
>> Those same mechanisms have provided hardware checksum support for a very long time.
>
> The new header and the payload are actually in different parts of the
> forwarding complex until they hit the output queue, you can't checksum
> data you don't have.

You can (and some do) the checksum component parts when things go into 
memory; the partial sums can be added as the parts are combined in the 
output queue.

I appreciate that we're all taking about what might be done, but the 
reality is that there are many 'transparent TCP proxies' that have to do 
this, so there's clearly a solution, and it clearly runs fast enough.

Joe