On Saturday, January 25, 2014 10:47:48 PM Curtis Villamizar wrote: > Reality check time. > > To get the PW over MPLS drafts past the TSV AD there is a > SHOULD regarding congestion control. > > AFAIK: No service providers ask for it. No one > implements it. If they did implement it no one would > deploy it. > > PW over MPLS is generally carrying relatively low volumes > of high priority traffic. The TC bits (MPLS flavor of > Diffserv DSCP) are used to enforce the higher priority. > If congestion occurs other traffic on that > infrastructure (typically plain old Internet) sees loss. > That is intended. This is the reality of how PW over > MPLS is deployed. > > Anyone who knows of implementation or deployment of > congestion control for PW over MPLS can correct me. And this is what I mentioned several weeks ago. As operators, we police traffic on ingress and egress (some operators shape on egress, but the result is the same), and this is how we control admission to the network. I have never used intrinsic congestion mechanisms in protocols (outside of lab fun-time when I'm really bored), and don't know anyone that has either. Of course, the risk is that router/switch vendors have all sorts of implementation as regards policing/shaping; but I can say that in the past 7x years or so (and especially in the past year for switches), this is reasonably mature, and no vendor worth their salt is shipping product that can't police or shape properly. Just one point to make, not all traffic being carried over MPLS is "high priority". Some of it really isn't, and is treated on a best-effort basis. But, this is all specific to operators and their customers. General traffic admission rules still apply all the same. Personally, if there was congestion mechanisms proposed as part of the MPLS-in-UDP spec., I would never run them as an operator. I'd rely on policing at the edge, as usual. Cheers, Mark.
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