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

[Jouni Korhonen <[e-mail]>]

Loa,

Correct. I kind of failed to say that :)

- Jouni


> On 09 Mar 2017, at 22:36, Loa Andersson <[e-mail]> wrote:
> 
> Jouni,
> 
> You say:
> 
>   Depending on the network topology the "overlay label" may be part of
>   the label stack.  This "L-label" has actually nothing specific to do
>   with DetNet but can be used to build overlay topologies over the
>   provider network in a same way virtual private networks (VPN) are
>   built.
> 
> What you sday about overlay topoöogies is correct, butthere is one more
> characteristic of the L-label it guarantee that the PW-label is
> unchanged from DA-x-PE to DA-x-PE, a tunnel that does not
> expose the PW-label other than to the DA-S-PE or the DA-T-PE is not
> optional, it must be there.
> 
> /Loa
> 
> 
> On 2017-03-10 13:58, 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?
>> 
>> 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?
>> 
>> 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
>> 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.
>> 
>> 
>> /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
>>> 
>>> 
>> 
> 
> -- 
> 
> 
> Loa Andersson                        email: [e-mail]
> Senior MPLS Expert                          [e-mail]
> Huawei Technologies (consultant)     phone: [phone]
> 
> _______________________________________________
> Detnet-dp-dt mailing list
> [e-mail]
> https://www.ietf.org/mailman/listinfo/detnet-dp-dt