Re: [Detnet-dp-dt] quick notes from 1/31/17 call

[Jouni Korhonen <[e-mail]>]

Lou,

> On Feb 2, 2017, at 4:43 AM, Lou Berger <[e-mail]> wrote:
> 
> Jouni/DT
> 
> Sounds like good progress - I have some questions /comments:
> 
> 1 mpls labels - svc vs transport vs hop-by-hop
> 
> I see that the mpls label is identified as a transport label that changes hop by hop.  While this is certainly a likely and perhaps initial use case, I think there are others that should be allowed for in the DetNet dp definition.  Perhaps just show it as a mpls label stack at the high level (this is what we ended up doing in the TP doc)?

I think we are in sync here. The current layout is an example with the most simplest label stack. I would not be surprised there are multiple labels below the PW label, not just one. Notation of n*4 or similar (LSE) for the lowest label would probably be better?


> I think other likely scenarios include 0|1 mpls domain service label followed by n (>1) domain transport labels. Where the n covers (or allows for) the hop by hop case, protection cases and even SR/spring label stacks.
> 
> Does this make any sense?
> 
> 2 qos
> 
> Documenting the progress on cos is certainly critical - and I don't want to detract from that. That said:
> 
> Was there any discussion on per DetNet flow resource management /  allocation, i.e. qos?  What’s your plane here?

Discussion yes, decisions no. Plan is rather vague atm. The resource management/allocation needs more input (I welcome it from anyone participating who has a good vision of it). One thing came regarding per detnet flow treatment. If we need to identify and treat every detnet flow individually at the transport level, we soon run out of identifier space without looking higher in the label stack.

> I suspect all already know my opinion, i.e., that the WG needs to cover both cases equally and in the same detnet data plane definition - At least from the DT perspective.

Understood.

- Jouni


> 
> Thanks,
> Lou
> 
> On 2/1/2017 9:02 PM, Jouni Korhonen wrote:
> 
> Present: Jouni, Loa, Norm, Balazs, Janos, Tal and David.
> 
> See the attached slideset that was used as the basis during the call.
> The MPLS-based PWE encaps has matured, except for: 1) fine grained CoS (i.e., 802.1 has discussed finer granularity of CoS basically to a flow level. The flow identification mechanism in .1CB, .1Qci et al allows this), and 2) PW CW SN width. We have discussed using 28 bits but that might cause issues when interworking with systems that only understand 16 bits (HSR and PRP as an examples).
> The CoS part and whether TC bits are copied between layers is still to be discussed further.
> IP PSN seems OK. The questions on the slides were discussed:
> - PW labels are still good to have. It makes the stack/implementation more streamlined between MPLS and IP PSNs. Also PW labels make PW switching way easier e.g., in a case of replication/elimination.
> - In a case of IP PSN each PW will have their own “tunnel” between T-/S-PEs. That means e.g., a PW between A and B will have different src/dst addresses than a PW between B and D. This makes pinned down paths easier to realize using IP PSN.
> 
> Norm asks for the cases where DetNet interworks with e.g. 802.1TSN. Would there be a way to regenerate MAC addresses if those are not transported over DetNet (this is for the case where the L2 is just so bug that interconnect does not make sense). Discussion.. Jouni commented that it is not in current document’s scope. Could be worked in parallel once the encaps for DetNet DP mature a bit.
> 
> Loa comments that EXP bits in an MPLS labels should use TC instead (Traffic Class), see RFC5462.
> 
> Jouni commented that we now start to have enough material to produce a draft of a draft. Expect the first version next week.
> 
> Quick discussion on 1588 PTP in DetNet. 1588 packets should not be replicated. Actually using DetNet encapsulation for them is not really a good idea. Tal will educate us more on that next time.
> 
> Action points:
> Tal will produce a slideset regarding his thoughts/concerns on 1588 transport in DetNet.
> 
> Next call: 2/7/17 10PM PDT
> 
> --
> Jouni Korhonen, Broadcom Ltd.
> M: [phone]
> 
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