Re: [tcpdump-workers] Z-Wave G.9959 TAP Specification version 0.94

[Chris Brandson via tcpdump-workers]

--- Begin Message ---
Hi Denis,

There are two length fields in the draft Z-Wave G.9959 TAP Specification. The 
TAP Header contains the length of the TLVs section (all the TLVs) and each TLV 
has it’s own length. It occurred to me that this may be confusing to the reader 
so I have given these different names in the 0.95 draft.

However, I think you are referring to the length of the MPDU itself. The Z-Wave 
G.9959 TAP Specification does not contain a length field for the MPDU because 
there is already a length provided in G.9959. I did not want to duplicate this 
value in the Z-Wave G.9959 TAP Specification as this could be problematic, for 
instance if these two length fields are different how should this be handled? 
To avoid this my preference is to re-use the length already in the Z-Wave MPDU.

To clarify that the MPDU length is contained within the MPDU itself I have 
modified this section to read:
The length of the Z-Wave MPDU Payload is contained within MPDU as defined in 
the Z-Wave MPDU format, see G.9959 [R1] section 8.1.3.4 and figures 8-5 and 
8-6. If needed, the Z-Wave MPDU Payload is padded at the end with zero octets 
to the next whole multiple of 4 octets.

The latest 0.95 draft of Z-Wave G.9959 TAP Specification with these changes is 
available at: https://gitlab.com/exegin/zwave-g9959-tap 
<https://gitlab.com/exegin/zwave-g9959-tap>

Thank-you very much for your feedback. Does this addresses your concern?

Hopefully this is sufficient to allocate a new DLT.

Regards,

+ Chris Brandson


> On Feb 6, 2023, at 3:10 PM, Denis Ovsienko via tcpdump-workers 
>  wrote:
> 
> 
> From: Denis Ovsienko 
> Subject: Re: [tcpdump-workers] Z-Wave G.9959 TAP Specification version 0.94
> Date: February 6, 2023 at 3:10:30 PM PST
> To: tcpdump-workers@lists.tcpdump.org
> 
> 
> On Mon, 12 Dec 2022 17:06:07 -0800
> Chris Brandson via tcpdump-workers 
> wrote:
> 
>> Hello Tcp Dump Workers,
>> 
>> The latest 0.94 draft Z-Wave G.9959 TAP Specification is available at:
>> 
>> https://gitlab.com/exegin/zwave-g9959-tap
>> <https://gitlab.com/exegin/zwave-g9959-tap>
>> 
>> This version incorporates feedback from Denis Ovsienko, James Ko, and
>> Sam Freemantle, whose contributions are appreciated.
>> 
>> Since there were no signifigant issues identified we requested that a
>> DLT value be assigned to this specification. Once assigned the
>> document will be updated with the DLT value and published as version
>> 1.0.
>> 
>> Comments and feedback are still appreciated.
> 
> Hello Chris.
> 
> Thank you for waiting.  I believe the last point I raised about the
> proposed encoding was that the currently specified header design makes
> it non-trivial to access any MPDU data beyond the Length header.
> However, if you find the current design good enough to serve the
> intended purpose, it would be wrong to argue, even more so since the
> header has a version field and can be improved later as and if required.
> 
> Are there any other objections to make this DLT allocation?
> 
> -- 
>Denis Ovsienko
> 
> 
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[tcpdump-workers] Z-Wave G.9959 TAP Specification version 0.94

[Chris Brandson via tcpdump-workers]

--- Begin Message ---
Hello Tcp Dump Workers,

The latest 0.94 draft Z-Wave G.9959 TAP Specification is available at:

https://gitlab.com/exegin/zwave-g9959-tap 


This version incorporates feedback from Denis Ovsienko, James Ko, and Sam 
Freemantle, whose contributions are appreciated.

Since there were no signifigant issues identified we requested that a DLT value 
be assigned to this specification. Once assigned the document will be updated 
with the DLT value and published as version 1.0.

Comments and feedback are still appreciated.

Regards,

+ Chris Brandson

Exegin Technologies
401 - 2071 Kingsway Avenue
Port Coquitlam BC V3C 6N2
Canada

This communication (and any information or material transmitted with this 
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review, retransmission, conversion to hard copy, copying, circulation, 
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communication, information or material is strictly prohibited and may be 
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Re: [tcpdump-workers] Public Release of Z-Wave G.9959 TAP Specification

[Chris Brandson via tcpdump-workers]

--- Begin Message ---
Hello Denis,

I agree with all of your suggestions, have made the changes and pushed to the 
repo.


> * Page 7: "Length is a minimum of 4 octets and must be a multiple of 4.
>  The addition of new TLVs does not and must not require incrementing
>  the version number." -- this definition automatically creates a
>  problem space on the receiving/reading end of this encoding because
>  slightly more than 75% of all possible length values are invalid by
>  definition. The classic solution would be not to include the first 4
>  octets into the length, and to count in multiples of 4, this way any
>  length value would be valid, free of underflows and better consumable
>  by simple parsers such as BPF bytecode.

The length is now the number of 4 octet (32-bit) words omitting the header.

> 
> * Page 8: "Z-Wave PHY Payload" -- is this the PPDU from Figure A.7 of
>  G.9959 2015/01, starting from "preamble sequence"?

This was an unfortunate mistake on my part. The intention was to specify the 
MPDU (not PPDU). This has been corrected and mapping to G.9959 added.

> 
> * Page 9: "length - number of octets for type in value field (not
>  including padding)" -- this definition looks better, but in the next
>  three TLV diagrams the length does include the T and the L.
> 

Lengths in the diagrams have been corrected.

> * Page 10: If the list of region code points is a copy/subset of an
>  external registry, it would help to give an exact reference.  Ditto
>  bit rate code points.  Clearly there is some relation with tables A.1
>  and A.2 from G.9959 2015/01.


References have need added.

Thank-you for your feedback.

Regards,

+ Chris Brandson--- End Message ---
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[tcpdump-workers] Public Release of Z-Wave G.9959 TAP Specification

[Chris Brandson via tcpdump-workers]

--- Begin Message ---
Hello everyone,

We are pleased to publish the draft Z-Wave G.9959 TAP Specification at:

https://gitlab.com/exegin/zwave-g9959-tap 
<https://gitlab.com/exegin/zwave-g9959-tap>

This provides a definition of a proposed Data Link Type (DLT) to encapsulate 
G.9959 frames captured by over-the-air packet capture hardware. This G.9959 TAP 
contains capture metadata both necessary correct interpretation of the frame 
format and capture metadata such as RSS (received signal strength) useful for 
network monitoring and maintenance. The frames encapsulated by the Z-Wave 
G.9959 TAP are specified in https://www.itu.int/rec/T-REC-G.9959 
<https://www.itu.int/rec/T-REC-G.9959>. 

Following review, and if needed any updates, it is requested that a DLT value 
be assigned to this specification. Once assigned the document will be updated 
with the DLT value and published as version 1.0.

Comments and feedback are appreciated.

Regards,

+ Chris Brandson

Exegin Technologies
401 - 2071 Kingsway Avenue
Port Coquitlam BC V3C 6N2
Canada

This communication (and any information or material transmitted with this 
communication) is confidential, may be privileged and is intended only for the 
use of the intended recipient. If you are not the intended recipient, any 
review, retransmission, conversion to hard copy, copying, circulation, 
publication, dissemination, distribution, reproduction or other use of this 
communication, information or material is strictly prohibited and may be 
illegal. If you received this communication in error, please notify us 
immediately by telephone or by return email, and delete this communication, 
information and material from any computer, disk drive, diskette or other 
storage device or media. Thank you. 


> On Nov 15, 2022, at 4:59 PM, Guy Harris via tcpdump-workers 
>  wrote:
> 
> 
> From: Guy Harris 
> Subject: Re: [tcpdump-workers] Resend: Request for new DLT Value
> Date: November 15, 2022 at 4:59:31 PM PST
> To: Chris Brandson 
> Cc: tcpdump-workers@lists.tcpdump.org
> 
> 
> On Nov 15, 2022, at 3:50 PM, Chris Brandson via tcpdump-workers 
>  wrote:
> 
>> The ITU Recommendation G.9959 document can be found here 
>> https://www.itu.int/rec/T-REC-G.9959 <https://www.itu.int/rec/T-REC-G.9959>. 
>> Work is ongoing on a wireshark dissector (hence the request for DLT 
>> LINKTYPE) and the TAP encapulation is still in development and will be 
>> published shortly. 
> 
> Let us know when you have a draft ready for us to look at.
> 
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[tcpdump-workers] Resend: Request for new DLT Value

[Chris Brandson via tcpdump-workers]

--- Begin Message ---
Hello,

I haven’t heard any response, perhaps because I was not subscribed the the 
mailing list? Apologies is this a repeat.

We are working on a new encasulation for ITU G.9959 frames. The plan is for it 
to be modelled after the LINKTYPE_IEEE802_15_4_TAP in the IEEE 802.15.4 TAP 
Link Type Specification 

 . However because of the signifigant differences between IEEE 802.15.4 and ITU 
G.9959 we will be publishing a new ITU G.9959 TAP specification. The TAP 
Specification will contain TLV values for ITU G.9959 specific meta-data such as 
region, mode, channel, RSSI, etc. and the payload will be actual ITU G.9959 
frames themselves.

We suggest a Linktype name of LINKTYPE_ITU_G9959_TAP and Description 

ITU-T G.9959 Short range narrow-band digital radiocommunication with a 
pseudo-header containing TLVs with metadata preceding the G.9959 header.

The ITU Recommendation G.9959 document can be found here 
https://www.itu.int/rec/T-REC-G.9959 . 
Work is ongoing on a wireshark dissector (hence the request for DLT LINKTYPE) 
and the TAP encapulation is still in development and will be published shortly. 

Thank-you and please let me know if any additional information is required.

+ Chris Brandson

Exegin Technologies
401 - 2071 Kingsway Avenue
Port Coquitlam BC V3C 6N2
Canada

This communication (and any information or material transmitted with this 
communication) is confidential, may be privileged and is intended only for the 
use of the intended recipient. If you are not the intended recipient, any 
review, retransmission, conversion to hard copy, copying, circulation, 
publication, dissemination, distribution, reproduction or other use of this 
communication, information or material is strictly prohibited and may be 
illegal. If you received this communication in error, please notify us 
immediately by telephone or by return email, and delete this communication, 
information and material from any computer, disk drive, diskette or other 
storage device or media. Thank you. 

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