+1 to what Joel said. It is clear that Joe's view of "fast enough" for a host
interface is not the same as my customer's view of "fast enough" for a core
router (nor should it be the same -- routers have to be faster than host
interfaces).
More important is the issue of what can we get vendors to implement, which is
probably better worded as what can we get network operators to push vendors to
implement. If you are talking about fundamentally changing the internal data
path for packets within a router or changing the data path into and out of
specific chips to carry significantly more information, then we are talking
about at least hundreds of millions and probably billions of dollars of
equipment that needs to be replaced. This needs a very compelling justification
before it is actually going to happen.
Ross
-----Original Message-----
From: mpls [mailto:mpls-bounces(_at_)ietf(_dot_)org] On Behalf Of Joel M.
Halpern
Sent: Monday, January 27, 2014 2:19 PM
To: Joe Touch; EXT - joelja(_at_)bogus(_dot_)com; stbryant(_at_)cisco(_dot_)com
Cc: mpls(_at_)ietf(_dot_)org; IETF discussion list
Subject: Re: [mpls] Last Call: <draft-ietf-mpls-in-udp-04.txt> (Encapsulating
MPLS in UDP) to Proposed Standard
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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