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

2014-01-22 09:52:28


On 1/14/2014 4:40 PM, Curtis Villamizar wrote:
In message <DB6CF60F-FFBA-47DA-9FD6-7288CCB260A6(_at_)netapp(_dot_)com>
"Eggert, Lars" writes:

On 2014-1-14, at 15:20, Stewart Bryant <stbryant(_at_)cisco(_dot_)com> wrote:
Yes, the inner (real) transport header is the only meaningful place
to apply congestion avoidance.

But what if the inner traffic isn't congestion controlled?

Lars


Lars,

The exact same thing will happen in all of the following cases:

   NON-congestion controlled application --over--
   UDP --over-- IP --over-- L2

   NON-congestion controlled application --over--
   UDP --over-- IP --over-- MPLS --over-- L2

   NON-congestion controlled application --over--
   UDP --over-- IP --over-- MPLS --over-- UDP --over-- IP --over-- L2

The non-congestion controlled application is what needs fixing.

In all three cases, RFC5405 expects that traffic inside UDP is congestion controlled. That can happen when the source application does so, but when that isn't known, it needs to happen at whatever layer puts the packet inside the UDP header that the Internet ends up seeing.

It would be wrong to try to put congestion control at every layer
underneath the non-congestion controlled application

Yes, but it's not wrong to require some sort of congestion control at any layer that generates a UDP packet inside the Internet or any other Internet-protocol-based network that has the same RFC5405 expectations.

Joe

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