+1
Edward Crabbe is right - the encapsulated protocols ought to take care
of congestion control when using UDP.
When they do NOT - e.g., when using MPLS to transfer traffic that either
isn't IP or is IP but isn't congestion controlled, then some other
mechanism needs to be employed.
It's not enough to assume "someone else, somewhere else" will handle this.
I agree with Lars - this needs to be part of the encapsulation protocol,
because it's not enforced by MPLS, and not provided by UDP.
Joe
On 1/10/2014 10:23 PM, Eggert, Lars wrote:
Hi,
On 2014-1-10, at 22:32, Scott Brim <scott(_dot_)brim(_at_)gmail(_dot_)com>
wrote:
OK good point - so we invoke the end-to-end argument on MPLS's behalf.
look at it the other way. From the viewpoint of the rest of the net, you are an
application using UDP. Such applications need to follow a set of principles we
have IETF consensus on (RFC5405).
By encapsulating MPLS in UDP, you are changing the game. That traffic can now
appear on any Internet path, and not just inside provisioned networks. Because
of that, you need a mechanism to detect if you are causing congestion, and a
mechanism to react to it.
And it *is* a requirement on the encapsulator, because from the perspective of
the rest of the net, that is the application that generates the UDP traffic.
Lars