Subject: [Detnet-dp-dt] Fresh read

From: Olivier Marce <[email-masked]>
Date: Thu, 10 Mar 2016 15:10:54 +0100

Hi all
as I was far behind from the current version of the document, I had an 
almost fresh read of it.

Comments and questions below, as well as change suggestions. If 
suggestion accepted I'll update the doc accordingly.
I've just updated the doc for few typos.

Talk to you.

1. Introduction

a)
Do we need to explicitly mention unicast or multicast, i.e. 99%+ of the 
traffic ?

b)
last sentence "Only the worst-
    case values for the mentioned parameters are concerned."
looks useless as long as we removed the reference to minimum latency,

c)
"There are three techniques  to achieve the QoS required by"
=>
"There are three techniques that can be used in conjunction with other 
techniques to achieve the QoS required by"

d)
"It does, however, elaborate what it would
    require to adapt and use the specific protocol as the deterministic
    networking data plane solution and only as a data plane solution."
=>
"It does, however, elaborate what it would
    require to adapt and use the specific protocol as the deterministic
    networking data plane solution, or part of, and only as a data plane 
solution."

3. DetNet adaptation to data plane

a)
Attached an openoffice drawing of what I understood from reading the 
section. Does this corresponds ? If so, we could add the corresponding 
text drawing to make its understanding easier.
If no, let me know.

b)
In 3. there is :
"The Net layer provides the
       networking between the end-points of a DetNet flow"
I think that "end-points" must be replaced by "crossed nodes"

c)
"The Net
    layer provides time and/or phase synchronization among network nodes,
    e.g., using IEEE 1588 or one of its Profiles."
It looks restrictive i.e. only NetLayer would be in charge of time 
synchronisation, while I could see 1588 applicable at the Det layer too.

d) I suggest, for readability,  to put this section after Criteria one, 
as it refers to criteria

4. Criteria for data plane solution alternatives

a)
"The solution alternative has to provide a mechanism for
    establishing explicit routes that all packets belonging to a
    deterministic flow / stream will follow.
"
This is a bit contradictory with replication text in 4.5. If all packets 
follow one (or several routes) this would mean that every replication 
will follow every routes.

=>
"The solution alternative has to provide a mechanism for
establishing explicit routes that at least one replication of all 
packets belonging to a
deterministic flow / stream will follow."

4.8 #8 Class and quality of service capabilities

Which signaling do we refer to in "This Criteria concerns the 
availability and mechanisms for the CoS
    and QoS marking and signaling as a part of the data plane protocol
    solution alternative."

Does this means that the protocol needs horizontal signaling between 
nodes, or vertical signaling for configuration/monitoring purpose... 
which is then part of O&M point ?

5.2.2 Analysis and Discussion
I feel that there is consistency issue regarding the "M" evaluation for 
IPv4.
It is evaluated M for IPv4 that does not really allow header options 
(almost ignored) while IPv6 is set to W while there is header options 
possible.
I feel that "Encapsulation and overhead evaluation" for IPv4 would be W/N

For similar reason "Packet sequencing " and "Packet replication and 
deletion" would be N for IPv4

5.3 Generic Routing Encapsulation (GRE)

Due to the fact that there is no room for extension as for IPv4, 
evaluation for "Explicit routes" should be N

5.6 PseudoWires
Not clear for we while we put M for "Encapsulation and overhead " of PW 
when we put W for IPv6.
Is it because almost all others criteria ar "M" too then there is no 
need to add header options, as opposed to IPv6.

5.8.1 Solution description
BFIR and BFER descriptions missing.
-- 
Olivier Marcé
Nokia Bell Labs France

---

From: János Farkas <[email-masked]>
Date: Thu, 10 Mar 2016 19:22:44 +0100

Hi Olivier,

Thanks for the comments!
Please find notes in-line on the ones related to text I added last week.

On 3/10/2016 3:10 PM, Olivier Marce wrote:
> section. Does this corresponds ? 
Yes it does.

> If so, we could add the corresponding text drawing to make its 
> understanding easier.
I cannot decide.
I'm happy for any improvements.

> I think that "end-points" must be replaced by "crossed nodes"
The text I wrote uses the term "edge nodes" which refer to edge nodes of 
a domain. I thought that is a well understood term, maybe I'm wrong.
I guess "crossed nodes" refer to "edge nodes". I'm not sure whether 
"crossed nodes" is clearer.

> synchronisation, while I could see 1588 applicable at the Det layer too.
The idea is that the Net layer provides synchronization. IEEE 1588 is 
just an example.
The time synchronization provided by the Net layer is then used by the 
Det layer, e.g. if the Det layer uses time stamping, which is only 
useful if time synchronization is available. That is how the 
responsibilities of the two layers can be divided.

Thanks and regards,
Janos