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

["Joel M. Halpern" <[e-mail]>]

Yes Joe, routers could ahve been built to do those calcualtions at that 
performance scale.
There are however two major problems:

1) That is not how routers are built.
2) The target performance scale is rather higher.

So could someone build an ASIC to do what you want?  Probably.  Is there 
any reason in the world to expect operators to pay the significant extra 
cost for such?  Not that I can see.
And even if we could and they would, that is not the world into which we 
are deploying these tunnels.

Yours,
Joel

On 1/27/14 1:53 PM, Joe Touch wrote:
>
>
> 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
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