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

[Edward Crabbe <[e-mail]>]

+1

Let the encapsulated transport protocols take care of the congestion
end-to-end.


On Fri, Jan 10, 2014 at 8:32 AM, Scott Brim <[e-mail]> wrote:

> I don't think it's right to try to solve this in MPLS, because MPLS is
> not a forwarding protocol - it's a connectivity protocol. In any use
> of UDP, congestion control is either left to something above UDP or
> ignored (left to queue management). Similarly, you want the client of
> MPLS to be responsible for managing its traffic. MPLS gives you paths,
> it doesn't push packets over them.
>
> Scott
>
>
> On Fri, Jan 10, 2014 at 11:09 AM, Eggert, Lars <[e-mail]> wrote:
> > Hi,
> >
> > On 2014-1-10, at 16:36, Joel M. Halpern <[e-mail]> wrote:
> >> Maybe I am completely missing things, but this looks wrong.
> >> If the MPLS LSP is carrying fixed rate pseudo-wires, adding congestion
> >> control will make it more likely that the service won't work.  Is that
> >> really the goal?
> >>
> >> We do not perform congestion control on MPLS LSPs.
> >> Assuming that a UDP tunnel is carrying just MPLS and was established
> >> just for MPLS, why would we expect it to behave differently than an MPLS
> >> LSP running over the exact same path, carrying the exact same traffic?
> >
> > we've been rehashing this discussion several times over the years, e.g.,
> for PWE, AMT, etc. In order to carry fixed-rate or otherwise
> non-congestion-controlled traffic over unprovisioned general Internet
> paths, there needs to be some sort of basic congestion control mechanism,
> like a circuit breaker.
> >
> > The whole point of running MPLS is to create networks in which paths are
> provisionable, so this is usually not an issue. But if you start sticking
> MPLS inside of UDP, those packets can go anywhere on the net, so you need
> mechanisms to control the rate of that traffic if it causes congestion, or
> at the very least you need to be able to stop the traffic if it creates
> severe congestion.
> >
> > Lars
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