Subject: [6tisch] Comment to draft-wang-6tisch-6top-coapie-01.txt

From: Tero Kivinen <[email-masked]>
Date: Tue, 21 Jul 2015 15:59:13 +0300

This draft plans to put the coap messages directly on the payload IEs
in the 802.15.4. The problem is that we only have 16 payload IE types
in total for 802.15.4, so reserving one number for coap might be hard.

On the other hand IEEE 802.15.9 needed to have solution to this same
problem, i.e how to multiplex upper layer data packet over 802.15.4
frames and how to fragment them so they can fit on the 802.15.4
frames.

The 802.15.9 is split in two layers, first one is the multiplexed data
service, which takes 16-bit MultiplexId and the data packet to be sent
to the other end, and it will fragment and deliver it to the other
end. The MultiplexId is used to separate different protocols using
this mechanism. One of those protocols is the key management protocols
providing KMP for 802.15.4, which is the second part of the 802.15.9.

Instead putting the coap messages in the payload IEs, it would
possible to allocate one MultiplexId for coap messages, and then coap
messages could be transmitted using multiplexing layer of 802.15.9.
This would also take care of fragmentting the messages (with PHY using
127 octet PSDU, the maximum size of the data packet is around 24kB).

The 802.15.9 recommended practice is already past the working group
letter ballots, and is starting its sponsor ballot soon. It is
expected to come out around the end of year. The draft will be
available on the ieee document store after the sponsor ballot starts,
i.e. very soon.
-- 
[email-masked]

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From: Qin Wang <[email-masked]>
Date: Tue, 21 Jul 2015 14:54:32 +0000 (UTC)

Hi Tero,
Thank you for your comments.
Before going to 802.15.9, I would like to discuss more about the coapie approach. In the 802.15.4e, the range (0x2-0x9) of group ID for payload IE is unmanaged. I thought IEEE802.15.4 WG had discussed how to use those Group ID, and also taken the requirement from 6tisch into consideration, and IEEE802.15.4 WG will assign a group ID to 6tisch. Am I wrong?
ThanksQin   

     On Tuesday, July 21, 2015 8:59 PM, Tero Kivinen <[email-masked]> wrote:

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https://www.ietf.org/mailman/listinfo/6tisch

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From: Tero Kivinen <[email-masked]>
Date: Tue, 21 Jul 2015 19:36:25 +0300

Qin Wang writes:
> Before going to 802.15.9, I would like to discuss more about the
> coapie approach. In the 802.15.4e, the range (0x2-0x9) of group ID
> for payload IE is unmanaged.

Not anymore. Now allocations are handled by IEEE 802.15 WPAN Assigned
Numbers Authority (ANA), and it has all of them marked as reserved:

Element ID  Assigned to               Assigned by     ID (decimal)
0           Encapsulated Service      802.15.4e-2012  0
            Data Unit (ESDU)        
1           MLME (nested)             802.15.4e-2012  1
2           Vendor specific           802.15.4-corr1  2
3           Multiplexed (MP) IE       802.15.9        3
4           Omnibus Payload Group IE  Wi_SUN          4
5           Reserved                                  5
6           Reserved                                  6
7           Reserved                                  7
8           Reserved                                  8
9           Reserved                                  9
A           Reserved                                  10
B           Reserved                                  11
C           Reserved                                  12
D           Reserved                                  13
E           Reserved                                  14
F           List termination          802.15.4e-2012  15

This is from the Payload IE Group IDs tab from the
https://mentor.ieee.org/802.15/dcn/13/15-13-0257-06-0000-802-15-4-ana-database.xlsx
document.

Link to the latest ANA database should be found from the
http://www.ieee802.org/15/ANA.html page (hmm... it seems to have link
to -05 revision, need to send request to fix that).

If you read the ANA rules (in that page, or from the IEEE 802.15
Working Group Operations Manual
https://mentor.ieee.org/802.15/dcn/10/15-10-0235-15-0000-802-15-operations-manual.docx)
you will notice that yes, IETF might request to get one payload IE
number to be shared for all IETF protocols.

Of course you could also use Vendor specific IE, which starts with
3-octet vendor OUI, and then rest of it free for vendor specific use. 

> I thought IEEE802.15.4 WG had discussed how to use those Group ID,
> and also taken the requirement from 6tisch into consideration, and
> IEEE802.15.4 WG will assign a group ID to 6tisch. Am I wrong?

The numbers are now allocated by ANA, but as there is already vendor
specific IE, and the 802.15.9 multiplexed IE which would most likely
work fine for 6tisch, I am not sure whether ANA would approve such
request. 
-- 
[email-masked]

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From: Qin Wang <[email-masked]>
Date: Tue, 21 Jul 2015 19:44:09 +0000 (UTC)

Tero, Many thanks for the information.
Pascal, regarding to the group ID of payload IE, where we are? Have we submitted some kind of request to IEEE802.15.4 WG as described in the section 13.4, https://mentor.ieee.org/802.15/dcn/10/15-10-0235-15-0000-802-15-operations-manual.docx? Have we got some answer? I may missed something. 
ThanksQin

     On Wednesday, July 22, 2015 12:36 AM, Tero Kivinen <[email-masked]> wrote:

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From: Paul Duffy <[email-masked]>
Date: Tue, 21 Jul 2015 16:12:45 -0400

> 127 octet PSDU, the maximum size of the data packet is around 24kB).

15.9 finally addresses the lack of upper level dispatch for 15.4. And 
also includes L2 fragmentation support.

I agree with Tero's advice.

Cheers

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From: "Pascal Thubert (pthubert)" <[email-masked]>
Date: Tue, 21 Jul 2015 22:12:06 +0000

I wondered the same, Qin.

Pat will know better ☺

Pascal

From: Qin Wang [mailto:[email-masked]]
Sent: mardi 21 juillet 2015 21:44
To: Tero Kivinen
Cc: [email-masked]; Pascal Thubert (pthubert); Thomas Watteyne
Subject: Re: [6tisch] Comment to draft-wang-6tisch-6top-coapie-01.txt

Thanks
Qin

On Wednesday, July 22, 2015 12:36 AM, Tero Kivinen <[email-masked]<mailto:[email-masked]>> wrote:

--
[email-masked]<mailto:[email-masked]>

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From: Pat Kinney <[email-masked]>
Date: Wed, 22 Jul 2015 02:46:54 -0500

Thanks Qin and Pascal;

As you know from subclause 13.4 of IEEE 802.15 WG’s Operation Manual, IEEE 802.15 WG needs a letter (or email attachment) from an IETF authority that could enforce the assurances necessary for the release of ID number assignment(s) from IEEE 802.15.  I was thinking that IANA could be that authority.  I can expedite the request within IEEE 802.15’s ANA once we receive that letter.

Pat

Pat Kinney
Kinney Consulting LLC
IEEE 802.15 WG vice chair, TG chair
ISA100.11a WG chair
O: +1.847.960.3715
[email-masked] <mailto:[email-masked]>
On 21, Jul2015, at 17:12, Pascal Thubert (pthubert) <[email-masked]> wrote:

Pat will know better J
 
Pascal

 
Pascal, regarding to the group ID of payload IE, where we are? Have we submitted some kind of request to IEEE802.15.4 WG as described in the section 13.4, https://mentor.ieee.org/802.15/dcn/10/15-10-0235-15-0000-802-15-operations-manual.docx <https://mentor.ieee.org/802.15/dcn/10/15-10-0235-15-0000-802-15-operations-manual.docx>? Have we got some answer? I may missed something. 
 
Thanks
Qin

On Wednesday, July 22, 2015 12:36 AM, Tero Kivinen <[email-masked] <mailto:[email-masked]>> wrote:

This is from the Payload IE Group IDs tab from the
https://mentor.ieee.org/802.15/dcn/13/15-13-0257-06-0000-802-15-4-ana-database.xlsx <https://mentor.ieee.org/802.15/dcn/13/15-13-0257-06-0000-802-15-4-ana-database.xlsx>
document.

Link to the latest ANA database should be found from the
http://www.ieee802.org/15/ANA.html  <http://www.ieee802.org/15/ANA.html>page (hmm... it seems to have link
to -05 revision, need to send request to fix that).

https://mentor.ieee.org/802.15/dcn/10/15-10-0235-15-0000-802-15-operations-manual.docx <https://mentor.ieee.org/802.15/dcn/10/15-10-0235-15-0000-802-15-operations-manual.docx>)

-- 
[email-masked] <mailto:[email-masked]>

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From: Tero Kivinen <[email-masked]>
Date: Wed, 22 Jul 2015 12:12:37 +0300

Pat Kinney writes:
> As you know from subclause 13.4 of IEEE 802.15 WG’s Operation
> Manual, IEEE 802.15 WG needs a letter (or email attachment) from an
> IETF authority that could enforce the assurances necessary for the
> release of ID number assignment (s) from IEEE 802.15. I was thinking
> that IANA could be that authority. I can expedite the request within
> IEEE 802.15’s ANA once we receive that letter.

If my reading is right then there will be one assignment for the whole
IETF, so we most likely would like to make RFC to specify how it is
splitted for different IETF protocols. I do not think COAP is the only
one in IETF who will ever want to use 802.15.4 payload IE. Most likely
adding one byte at the start of payload IE would be enough as
multiplexer for the rest of the payload...

On the other hand as I already told that 802.15.9 already does that
and even more, and the multiplex id there is 16-bit so getting numbers
from there is easier, and getting one number for CoAP would be no
problem etc.

Btw, the overhead of 802.15.9 is as follows:

If frame fits in one 802.15.4 frame 1+2 = 3 octets (1 for MP IE
control, and 2 for ethertype).

If it does not fit in one frame, and needs to be fragmented, then the
overhead will be 1+1+2+2 = 6 octets (1 for MP IE control, 1 for
fragment number, 2 for total payload length, and 2 for ethertype) for
the first frament and 1+1 = 2 octets (MP IE control, fragment number)
for rest of fragments.

In addition to that there is of course MAC header, Header IE
termination IE, and Payload IE header overhead for each fragment.
-- 
[email-masked]

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From: Qin Wang <[email-masked]>
Date: Thu, 23 Jul 2015 14:28:43 +0000 (UTC)

Hi Pat,
Since there are two approaches mentioned in the discussion, i.e. (1) containing 6top-to-6top message in a specific payload IE (coapie), (2) using the mechanism provided by IEEE802.15.9 to convey the 6top-to-6top message, I would like to do more evaluation. I couldn't find the IEEE802.15.9 spec on IEEE802 website. Can you tell me how to get it?
ThanksQin