There's an opportunity to define a simple generic IPv6 encapsulating mechanism
a la UDP, but
with a payload checksum of varying coverage (header only, partial payload, full
payload)
and with the (stronger than UDP) checksum placed at the end of the packet.
Lloyd Wood
http://about.me/lloydwood
________________________________________
From: ietf [ietf-bounces(_at_)ietf(_dot_)org] On Behalf Of Stewart Bryant
[stbryant(_at_)cisco(_dot_)com]
Sent: 16 January 2014 17:35
To: Eggert, Lars; Joel Jaeggli
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
On 16/01/2014 17:19, Eggert, Lars wrote:
Hi,
On 2014-1-16, at 18:06, joel jaeggli <joelja(_at_)bogus(_dot_)com> wrote:
These tunnels are stateless
yep. (But they don't have to be.)
Ah, they do if they are to scale. State at speed is really hard. The sort
of systems we are talking about do things like pipeline counters
and it is loooooots of packets later before the counter is actually
incremented.
The endpoints not the encapsulators have visibility into the
end-to-end loss latency properties of the path.
Yep. But when you tunnel some L2 in UDP, apps that were limited to L2 domains
- where not reacting to congestion may be OK - can now go over the wider
Internet, where this is not OK.
I'd be great if those apps would change. But in the meantime, it's the duty
of the encapsulator - who enables this traffic to break out of an L2 domain
and go over the wider net - to make sure the traffic it emits conforms to our
BCPs.
the encapsulator is an intermediate hop, similar to any other router
in the path.
It's not. For the rest of the network, that encapsulator is indistinguishable
from any other app that sends UDP traffic.
UDP is a transport-layer protocol, and we have practices how it is to be used
on the net. If you want to use it for encapsulation, you bind yourself to
these BCPs.
Look at it the other way: if transport area folks would want to send MPLS
packets into the network in some problematic way, I'm sure the routing and
ops folks would not be amused.
The root cause of the problem here is that UDP, has bifurcated into
a general purpose encapsulation.
Stewart