Re: [Detnet-dp-dt] Draft update in github

[Jouni Korhonen <[e-mail]>]

Carlos, Loa,



> On Mar 11, 2017, at 6:49 AM, Carlos Jesús Bernardos Cano <[e-mail]> wrote:
> 
> Hi,
> 
> On Fri, 2017-03-10 at 13:58 +0800, Loa Andersson wrote:
>> Jouni,
>> 
>> I was working on reviewing the previous version, I see that
>> you captured most of (very close to sll<9 of the comments I had.
>> 
>> Questions:
>> 
>> 1. IETF is mostly doing "on the wire" specifications, what is in the
>> box is mostly viewed as implementation specific. Against this
>> background
>> why do we need "local-ID", isn't that implementation specific?

I was thinking more like giving an example of a possible implementation. I got the feeling that if we say nothing about the local-ID folks will start asking how this is going to work.. In that sense the flow-ID as-is “safer” because it is also on-wire.


>> 
>> 2. There are two sentences "In the context of this document DA-T-PE
>> is
>> referred as T-PE." and "In the context of this document DA-S-PE is 
>> referred as S-PE." Wouldn't it be better to actually use the new
>> abbreviations, DA-T-PE and DA-S-PE?
> 
> I agree with this. I've just committed a new version that (except for
> the appendixes) only uses DA-*-PE. I've reworked the figures.

Yes. Agree as well. I tried to follow the new naming at least in the new text. Some old text probably has wrong terminology in places.

> 
> Carlos
> 
>> 
>> 3. Then I wonder if you got what is optional in the label stack
>> and what is not; what needs to be there is one single tunnel, we have
>> called that L-labels (PW architecture call it PSN Tunnel) all the
>> rest
>> of the T-Label tunnels are  optional.
>> 
>> I wrote it down like this:
>> 
>>     +-------------------------------+
>>     |                               |
>>     |          DetNet Flow          |
>>     |            Payload            |  n octets
>>     |                               |
>>     +-------------------------------+
>>     |      DetNet Flow Id           |  4 octets
>>     +-------------------------------+
>>     |      DetNet Control Word      |  4 octets
>>     +-------------------------------+
>>     |          MS-PW Label          |  4 octets
>>     +-------------------------------+
>>     |            L-Label            |  4 octets
>>     +-------------------------------+
>>     |   (optional) MPLS T-Label(s)  |  n*4 octets (four octets per
>> label)
>>     +-------------------------------+
>> 
>> 
>> DetNet Flow Payload - n octets
>> DetNet Flow Id      - 4 octets, part of the encapsualtion header,
>>                        i.e. not in the label stack
>> DetNet Control Word - 4 octets, the 16 least significant but are a
>>                        a sequence number.
>> MS-PW Label         - 4 octets, this label is unchanged between two
>>                        DA-x-PEs, and at PW set up it is decided if
>>                        the Native Service Processing includes DetNet
>>                        FRER or not, the MS-PW Label is swapped at
>>                        DA-S-PE.
>> L-Label             - carries the MS-PW Label unchanged from one
>>                        DA-x-PE to the next

So far we had the assumption that L-label also remains unchanged between the endpoints the tunnel is set up.. like from T-PE to S-PE. Does this still hold?

The reason why I still keep L-labels around is that it allows easily configure some S-PEs as a pass through.

- Jouni


>> T-Label(s)          - are optional, and strictly not part of the
>>                        DetNet encapsulation.
>> 
>> I don't want you to change but maybe capture a few bits and pieces
>> from this.
>> 
>> Then I have one ridiculous concern, the DA-S-PE does not need to 
>> interface a CE, and does not necessarily sit on a domain border, and
>> is
>> tthus not necessary a "real" PE. If we ant to keep calling it a PE
>> (I think we should), we should have some words around this.

I think we should be covered by MS-PW (RFC6073) description of S-PE.

- Jouni

>> 
>> 
>> /Loa
>> 
>> 
>> On 2017-03-10 12:55, Jouni Korhonen wrote:
>>> Folks,
>>> 
>>> I did quite a bit of updates to the draft. All in GitHub. I’ll
>>> continue writing over the weekend etc..
>>> 
>>> - Jouni
>>> 
>>> 
>> 
>> 
> 
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