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

[Jouni Korhonen <[e-mail]>]

>>> 
>>> The relationship between the MPLS transport profile and MPLS is that MPLS-TP is a true subset of MPLS, i.e. anything new that was defined for
>>> MPLS-TP is also applicable for MPLS. On the other hand MPLS-TP explicitly excluded a couple of things that is part of MPLS. The two
>>> most important things that were excluded was that
>>> (1) you can not assume the presence of IP or IP routing in MPLS-TP
>>> (2) PHP is always disabled
>> 
>> Yes... and? I think you cannot assume the presence of IP in a case detnet either,
> 
> fine, but it only works one way (all ravens are black, but not all black
> birds are are ravens). So DetNet is L2 bridged or L3 routed, no
> alternatives, right?
> 
> and PHP can always be turned off my configuration.
> 
> not in MPLS-TP, there it can only be disabled, not enabled if you need
> it (read depth of label stack).

I was referring to MPLS and its use of PHP, where it can be turned off by configuration. MPLS-TE has it always off as you originally pointed out.

>>> The DetNet charter says:
>>> 
>>> The Deterministic Networking (DetNet) Working Group focuses on
>>> deterministic data paths that operate over Layer 2 bridged and Layer 3
>>> routed segments, ...
>>> 
>>> Since MPLS-TP is neither "Layer 2 bridged" or "Layer 3 routed". to me
>>> it looks like MPLS-TP is excluded.
>> 
>> I don’t quite get the conclusion here. Maybe I am thinking too simple but for me MPLS-TP in DetNet DP case is just labels.
> 
> just labels, does not make it MPLS-TP, it makes it mpls, which I take to mean that you can use an MPLS-TP tunnel (by making i show up 

Exactly. And this should be just fine for the DP. 

> in the
> routing as a adjacency, but since you can't enable PHP it is at best
> risky to have an MPLS-TP tunnel terminating on the same node as the
> ms-pw label

That is a downside that I think we acknowledged earlier, and we need to make sure the document also mentions it. For some hardware lack of PHP is not that much of an issue as long as the label stack depth is reasonable. 

We wouldn’t have LSP merge and ECMP with MPLS-TP either.. On the other hand I find bi-directional LSPs and not losing the origin/source information usable. Also the bias towards manually set up LSPs fits to some centrally controlled use cases nicely.

> So my conclusion is that we can use TP for transport, as long as there
> are no impact on the DetNet encapsulation.
> 
> Makes sense?

Yes.

- Jouni

> 
> /Loa
> 
>> 
>> - Jouni
>> 
>> 
>>> 
>>> /Loa
>>> 
>>> 
>>>> 
>>>> Most of the DetNet DP “sauce” is on the PW layer. We already assured that the PSN can be either a LSP or IP. Since MPLS-TP includes PWE is see no reason why “MPLS-based” PSN could not also be implemented using MPLS-TP.
>>>> 
>>>>> 2. How are organizing to work on the first draft text? I'm available to
>>>>> contribute text.
>>>> 
>>>> I’ll get the first round up soon. Then we can divide the job into sections that everybody (volunteering) is responsible for.
>>>> 
>>>> - Jouni
>>>> 
>>>> 
>>>> 
>>>>> 
>>>>> Thanks!
>>>>> 
>>>>> Carlos
>>>>> 
>>>>> On Wed, 2017-02-01 at 18:02 -0800, 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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>>>>>> [e-mail]
>>>>>> https://www.ietf.org/mailman/listinfo/detnet-dp-dt
>>>> 
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>>> 
>>> --
>>> 
>>> 
>>> Loa Andersson                        email: [e-mail]
>>> Senior MPLS Expert                          [e-mail]
>>> Huawei Technologies (consultant)     phone: [phone]
>> 
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>> 
> 
> -- 
> 
> 
> Loa Andersson                        email: [e-mail]
> Senior MPLS Expert                          [e-mail]
> Huawei Technologies (consultant)     phone: [phone]