Re: [6tisch] comments on 15.4 header fields in minimal

Wed, 09 Sep 2015 07:17:15 -0700

[The following summary is from memory, based on detailed analysis years ago to make ISA 100.11a into an IEC standard that defaults to, and can be configured to, conform to European Norms.]

Blacklisting frequencies does not change "the number of available frequencies"; it merely declares that specific "available frequencies" in the spread-spectrum rotation cycle are never to be used.

It may appear to the casual reader that these two concepts are the same, but in terms of EN 300 328, the regulations that apply to use of 2.4 GHz spread-spectrum signaling in the EC, they are not. Reducing the number of distinct frequencies in the spread-spectrum rotation cycle to less than 16 makes use of IEEE 802.15.4 at needed power levels illegal in the European Community, due to the requirements of EN 300 328 that apply when operating at power levels above 1 mW EIRP.

EN 300 328 v1.8.1 is the the current relevant regulation, which will soon be replaced by EN 300 328 v1.9.1. Both require that devices operating under IEEE 802.15.4 and similar regimes have a spread-spectrum schedule with at least 16 distinct non-overlapping frequency channels. EN 300 328 does not require that all of the frequencies be used, but only that time is allocated in the schedule rotation for their use. Thus blacklisting some of the 16 frequency channels while leaving them in the spread-spectrum rotation schedule enables IEEE 802.15.4 to meet the EN 300 328 requirements, whereas operation at needed transmit power levels would become prohibited if the spread-spectrum rotation were reduced to fewer than 16 frequency channels.

-Tom
====
On 2015.09.08 23:38, Xavier Vilajosana wrote:
Hi Pascal, All,

thanks. I addressed your comments. 

As a note about this:


>>>>>>
 I had second thoughts about the 
Number of available frequencies    | 16

 

Shouldn’t we allow a given configuration to blacklist / whitelist some ?

>>>>>>>>


I would prefer to let it as is, i.e we say we have 16 available frequencies, but we do not restrict to use all of them or a subset. We just say that 16 are available.

Another important point that is missing is related to this comment pointed out by Jose Angel Miranda.

>>>>>>>>>>>>>>>>>
The last topic has to do with the periodic beacon addressing format.
Following the standard ieee802.15.4e-2012, point 5.1.6.2 “Reception and
rejection”: “…If a destination PAN identifier is included in the frame, it
shall match *macPANId *or shall be the broadcast PAN identifier…”

Having a not associated mote, which does not have macPanId yet, would not
be able to filter correctly the periodic beacon transmitted by a
(PAN)Coordinator, which follows draft-ietf-6tisch-minimal-11.


We propose the use of the next combination for a periodic beacon in a TSCH
network (following table 2a in [IEEE802154-2012]):

-          Sequence Number: Not Present (not necessary).

-          Destination PANID: Not Present.

-          Destination Address: Not Present.

-          Source PANID: Present.

-          Source Address: Present (Short mode).
>>>>>>>>>>>>>>>>>>
My proposal here is something in the middle.  (We want Sequence Numbers to match packet and ack). We want long addresses to avoid a Short->Long address mapping service in minimal.
The PAN ID Compression bit in a BEACON frame MUST indicate that the Source PAN ID is "Present" and the Destination PAN ID is "Not Present". The source and destination address fields MUST be filled with an extended address (64 bit) and this be indicated in the corresponding Frame Control field. 

Note also that the first sentence of this section enforces the following:
"The IEEE802.15.4 header of all frames MUST include the Sequence Number field, the Source Address field and the Destination Address field. Frame Version field MUST be set to 0b10 (Frame Version 2)."



Please provide your input on this topic (specially those having running code and networks already deployed). 
Regards,
Xavi

          



          

        

      

      


        
2015-09-07 9:11 GMT+02:00 Pascal
          Thubert (pthubert) <[email protected]>:

          

            

              

                
Hello
                    Xavi:

                
 

                
I
                    like this text since it makes the normative text
                    mostly independent on IEEE specs and their
                    evolution.

                
 

                
There
                    seems to be an agreement in Prague that the best
                    direction to sort the issues with -2011 would be to
                    align to the next revision so that everybody is
                    ready for 802.15.4-2015. I’ve been wondering how and
                    where to reflect that, like a few words in the annex
                    with the IE examples. Any suggestion?

                
 

                
 

                
Some
                    quick notes:

                

                  
 

                

                
 

                
 

                
The packet formats are specific for the
                    [IEEE802154-2012]

                
   revision and MAY vary in future
                    releases of the IEEE standard.
                  

                
 

                
 

                
I’d
                    suggest to lowercase that MAY, this text is not
                    normative. On the side, I’d also lowercase the text
                    in the introduction, in particular the MUST.

                
 

                

                  
 

                

                
 

                
 

                
I had second thoughts about the 

                
Number of available frequencies    | 16

                
 

                
Shouldn’t
                    we allow a given configuration to blacklist /
                    whitelist some ?

                
 

                

                  
 

                

                
 

                
 

                
 

                
Looking
                    at section 4, I’d rather indicate what the goal is
                    as opposed to how it is encoded and then indicate
                    how it is encoded in the current IEEE specs. e.g:

                
                  
 

                  
 

                  
      the PAN ID Compression bit MUST be set to 0b0.  According to the

                
                
      Table 2a in [IEEE802154-2012], this translates into the

                
                  
      Destination PAN ID field being "Present" and the Source PAN ID

                  
      field being "Not Present".

                  
 

                
                
This
                    text has an expectation on encoding that may change.
                    Suggestion is to change to:

                
 

                
      the PAN ID Compression MUST indicate that the

                
      Destination PAN ID field is "Present" and the Source PAN ID

                
      field is "Not Present". With [IEEE802154-2012] and according to

                
      Table 2a, this is accomplished by setting the PAN ID Compression

                
      bit to 0b0.  

                
 

                

                  
 

                

                
 

                
   Unicast frames sent to a unicast MAC destination address request an

                
   acknowledgment.

                
 

                
Somehow
                    this sentence was truncated?

                

                  
 

                

                
 

                
One RECOMMENDED way to achieve this in an

                
      interoperable fashion is to set Sp to 2*ETX.

                
 

                
Just
                    a reminder that we discussed in Prague that we
                    should use (3*ETX -2) so that an ETX of A would
                    result in MINIMUM_STEP_OF_RANK of 1

                

                  
 

                

                
 

                
 

                
 

                
All
                    the best,

                
 

                
Pascal

                
 

                

                  

                    

                      
From:
                          6tisch [mailto:[email protected]]
                          On Behalf Of Xavier Vilajosana

                          Sent: lundi 7 septembre 2015 05:30

                          To: [email protected]

                          Cc: Robert Cragie <[email protected]>;
                          José Ángel Miranda <[email protected]>;
                          Jonathan Simon <[email protected]>;
                          Pat Kinney <[email protected]>

                          Subject: Re: [6tisch] comments on 15.4
                          header fields in minimal

                    

                  

                  

                    

                      
 

                      

                        
Dear all,

                        

                          
 

                        

                        

                          
after the last WG webex
                            meeting on Friday we decided to finalize
                            this discussion and come out with a proposal
                            on the IEEE802.15.4 specific header fields
                            and what minimal should say about that.

                        

                        

                          
 

                        

                        

                          
the threads where this is
                            being discussed are:

                        

                        
                        

                          
 

                        

                        

                          
and 

                        

                        
                        

                          
 

                        

                        

                          
 

                        

                        

                          
My proposal is to find a
                            text for minimal that does not restrict the
                            implementation to any version of 15.4 but
                            instead indicates that the (PANID
                            Compression bit) is used according to the
                            underlying 15.4 version implemented. 

                        

                        

                          
 

                        

                        

                          
here a proposal:

                        

                        

                          
 

                        

                        

                          

                            
"The IEEE802.15.4
                              header of all frames MUST include the
                              Sequence Number field, the Source Address
                              field and the Destination Address field
                              and only the Destination PANID. Frame
                              Version field MUST be set to 0b10 (Frame
                              Version 2).  

                          

                          

                            
When using  DATA,
                              ACKNOWLEDGEMENT, MAC COMMAND frame types
                              the source and destination address fields
                              MUST be filled with an extended address
                              (64 bit) and this be indicated in the
                              corresponding Frame Control field. The
                              Destination PANID MUST be present, the
                              Source PANID MUST be elided and the PANID
                              Compression bit MUST be set or clear
                              according to the specific IEEE802.15.4
                              implementation. "

                          

                        

                        

                          
 

                        

                        

                          
As per Jose (Kirale)
                            email there are several cases where this
                            implementation would require a special
                            handling of packets when running in minimal
                            compliant mode. Although this might work,
                            maybe is time to also make things simple and
                            not force another set of IF cases to support
                            that mode.  

                        

                        

                          
 

                        

                        

                          
Finally, note that this
                            is for minimal, which is a fallback mode of
                            operation or used for initial interop
                            testing. This means that this mode of
                            operation is not the one that will be
                            running in most of the networks all the time
                            but instead will be switched on when
                            something fails or the network initializes.

                        

                        

                          
 

                        

                        

                          
regards,

                            Xavi

                        

                      

                      

                        
 

                        

                          
2015-07-27 11:00
                            GMT+02:00 Robert Cragie <[email protected]>:

                          

                            

                              
For some reason, it
                                was deemed necessary to change PAN ID
                                compression in 802.15.4-2012 for frame
                                version 2 but there is an issue with the
                                case where:

                              

                                
 

                              

                              

                                
* both addresses
                                  are present

                              

                              

                                
* either or both is
                                  a short address

                              

                              

                                
* PAN ID
                                  compression is set to 1

                              

                              

                                
 

                              

                              

                                
In this case the
                                  inferred PAN ID is 0xffff but it is
                                  not possible to distinguish an
                                  identical short address which may be
                                  allocated in different PANs. So I
                                  believe the decision was to keep the
                                  original format for PAN ID compression
                                  where either or both are short
                                  addresses but to change the behaviour
                                  if both addresses are extended
                                  addresses. I have already pointed out
                                  that this is a significant change from
                                  frame version 0/1 and changes the
                                  meaning for PAN ID compression. See
                                  the analysis document I sent out
                                  earlier.

                              

                              

                                
 

                              

                              

                                
I don't actually
                                  see how 802.15.4e-2012 Table 2a can
                                  actually be used as it is erroneous as
                                  described above. I would be interested
                                  to know if anyone is doing it this
                                  way, especially using PAN ID
                                  compression set to 1.

                              

                              

                                
 

                              

                              

                                
Robert

                              

                            

                            

                              

                                

                                  
 

                                  

                                    
On 27 July 2015
                                      at 05:52, Xavier Vilajosana <[email protected]>
                                      wrote:

                                    

                                      

                                        
Hi,

                                        

                                          
 

                                        

                                        

                                          
we
                                            discussed this concern at
                                            the IETF meeting. In minimal
                                            we wanted to support what is
                                            already standardized
                                            (15.4e-2012) but it seems
                                            that if we make things align
                                            to 2012 then we won't be
                                            compatible with 2015. If we
                                            try to make the text less
                                            specific aiming to have
                                            people use the table they
                                            want we loose some how the
                                            sense of minimal as
                                            different people
                                            implementing it will have
                                            different configurations
                                            (specially PIDC bits set).

                                        

                                        

                                          
 

                                        

                                        

                                          
So, what
                                            do we do?

                                        

                                        

                                          
 

                                        

                                        

                                          
 

                                        

                                      

                                      

                                        

                                          

                                            
 

                                            

                                              
2015-07-26
                                                2:50 GMT+02:00 Jonathan
                                                Simon <[email protected]>:

                                              

                                                

                                                  
I
                                                    noticed I said
                                                    15.4-2012 in my
                                                    previous email.  I
                                                    meant 15.4e-21012 in
                                                    case it wasn't
                                                    clear.

                                                  

                                                    

                                                      
 

                                                      

                                                        
 

                                                        

                                                          
On
                                                          Sat, Jul 25,
                                                          2015 at 11:39
                                                          AM, Robert
                                                          Cragie <[email protected]>
                                                          wrote:

                                                          

                                                          

                                                          
I
                                                          too have some
                                                          concerns with
                                                          the way the
                                                          PAN ID
                                                          compression is
                                                          used for frame
                                                          version 2.
                                                          Please see
                                                          attached
                                                          analysis
                                                          regarding PAN
                                                          ID
                                                          compression.

                                                          

                                                          
 

                                                          

                                                          

                                                          
Robert

                                                          

                                                          

                                                          

                                                          
 

                                                          

                                                          
On
                                                          24 July 2015
                                                          at 21:00,
                                                          Jonathan Simon
                                                          <[email protected]>
                                                          wrote:

                                                          

                                                          

                                                          
Pat
                                                          - I’m noticing
                                                          some
                                                          differences
                                                          between the
                                                          proposed table
                                                          and the one in
                                                          15.4-2012.

                                                          

                                                          
 

                                                          

                                                          

                                                          
In
                                                          15.4-2012, the
                                                          last 2 rows of
                                                          table 2a are

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
SRC addr   DST addr    SRC PAN          DST
                                                          PAN        
                                                          PIDC

                                                          

                                                          

                                                          
Present    Present     Not Present    
                                                           Present      
                                                            0    (row
                                                          12)

                                                          

                                                          

                                                          
Present    Present     Not Present      Not
                                                          Present     1
                                                             (row 13)

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
In
                                                          the proposed
                                                          table, rows
                                                          12-14
                                                          correspond to
                                                          the 2012 row
                                                          12 case

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
SRC addr   DST addr    SRC PAN          DST
                                                          PAN       
                                                           PIDC

                                                          Extended
                                                            Short    
                                                            Not Present
                                                               Present  
                                                                1

                                                          Short    
                                                           Extended  
                                                           Not Present  
                                                             Present    
                                                              1

                                                          Short    
                                                           Short    
                                                            Not Present
                                                               Present  
                                                                1

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
So
                                                          the PIDC bit
                                                          is inverted
                                                          from the
                                                          previous
                                                          version for
                                                          some address
                                                          sizes, but for
                                                          both extended
                                                          addresses (new
                                                          table row 7),
                                                          you keep the
                                                          original
                                                          sense:

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
SRC addr   DST addr    SRC PAN          DST
                                                          PAN       
                                                           PIDC

                                                          Extended
                                                            Extended  
                                                           Not Present  
                                                             Present    
                                                              1

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
This
                                                          breaks
                                                          backward
                                                          compatibility
                                                          for older
                                                          applications
                                                          that weren’t
                                                          considering
                                                          address size.

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
There
                                                          is no row in
                                                          the new table
                                                          that
                                                          corresponds to
                                                          2012 row 13
                                                          for mixed or
                                                          short
                                                          addresses. 
                                                          This breaks
                                                          our existing
                                                          IP product
                                                          implementation.

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          

                                                          

                                                          
-- 

                                                          Jonathan

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          

                                                          

                                                          

                                                          

                                                          
On
                                                          Jul 21, 2015,
                                                          at 11:26 PM,
                                                          Pat Kinney
                                                          <[email protected]>
                                                          wrote:

                                                          

                                                          
 

                                                          

                                                          

                                                          

                                                          

                                                          

                                                          

                                                          
As
                                                          per our 6tisch
                                                          meeting
                                                          yesterday
                                                          concerning the
                                                          PAN ID
                                                          compression
                                                          bit table, I
                                                          have attached
                                                          an IEEE 802.15
                                                          document
                                                          showing the
                                                          changes to the
                                                          latest
                                                          revision
                                                          draft. This
                                                          document will
                                                          act as
                                                          guidance to
                                                          the Technical
                                                          Editor to
                                                          modify the
                                                          revision
                                                          draft.  In
                                                          summary, it
                                                          was agreed
                                                          that frames of
                                                          version
                                                          numbers “0” or
                                                          “1" should
                                                          revert to the
                                                          instructions
                                                          stated in IEEE
                                                          802.15.4-2011. 
                                                          For frame
                                                          version “2",
                                                          new text will
                                                          be inserted
                                                          into the
                                                          revision
                                                          declaring the
                                                          rules in a
                                                          non-ambiguous
                                                          fashion.

                                                          

                                                          
 

                                                          

                                                          

                                                          
I
                                                          would ask
                                                          those
                                                          interested in
                                                          setting the
                                                          header bits to
                                                          read this
                                                          document and
                                                          respond with
                                                          critiques or
                                                          questions.

                                                          

                                                          
 

                                                          

                                                          

                                                          
Thanks,
                                                          Pat

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          

                                                          

                                                          

                                                          

                                                          

                                                          
Pat
                                                          Kinney

                                                          

                                                          

                                                          
Kinney
                                                          Consulting LLC

                                                          

                                                          

                                                          
IEEE
                                                          802.15 WG vice
                                                          chair, TG
                                                          chair

                                                          

                                                          

                                                          
ISA100.11a
                                                          WG chair

                                                          

                                                          
                                                          
                                                          

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          

                                                          

                                                          

                                                          

                                                          

                                                          

                                                          

                                                          

                                                          
<15-15-0561-03-0mag-yet-another-document-explaining-pan-id-compression
                                                          (1).docx>

                                                          

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
On
                                                          21, Jul2015,
                                                          at 12:46,
                                                          Xavier
                                                          Vilajosana
                                                          <[email protected]>
                                                          wrote:

                                                          

                                                          
 

                                                          

                                                          

                                                          

                                                          

                                                          
Hi,

                                                          

                                                          
 

                                                          

                                                          

                                                          
From
                                                          the discussion
                                                          today, the
                                                          section
                                                          mandating the
                                                          use of certain
                                                          2012 specific
                                                          configuration
                                                          needs to be
                                                          changed so we
                                                          can be
                                                          independent to
                                                          the evolution
                                                          of the 15.4
                                                          spec. 

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
The
                                                          current text
                                                          is:

                                                          

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
The
                                                          IEEE802.15.4
                                                          header of all
                                                          frames MUST
                                                          include the
                                                          Sequence
                                                          Number field,
                                                          the Source
                                                          Address field
                                                          and the
                                                          Destination
                                                          Address field.

                                                          

                                                          

                                                          
In
                                                          the Frame
                                                          Control Field,
                                                          this
                                                          translates to:

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
the
                                                          Frame Version
                                                          field MUST be
                                                          set to 0b10
                                                          (Frame Version
                                                          2)

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
the
                                                          Sequence
                                                          Number
                                                          Suppression
                                                          bit MUST be
                                                          set to 0b0 

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
the
                                                          Source
                                                          Addressing
                                                          Mode MUST set
                                                          to 0b11 (long
                                                          address)

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
the
                                                          Destination
                                                          Addressing
                                                          Mode MUST set
                                                          to 0b11 (long
                                                          address)
                                                          except for the
                                                          broadcast
                                                          address for
                                                          which
                                                          Destination
                                                          Addressing
                                                          Mode SHOULD
                                                          set to 0b10
                                                          (short
                                                          address). The
                                                          use of long
                                                          addresses is a
                                                          REQUIRED as no
                                                          association
                                                          procedure is
                                                          defined in
                                                          this document.

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
the
                                                          PAN ID
                                                          Compression
                                                          bit MUST be
                                                          set to 0b0.
                                                          According to
                                                          the Table 2a
                                                          in
                                                          IEEE802154-2012
                                                          this
                                                          translates
                                                          into the
                                                          Destination
                                                          PAN ID field
                                                          being
                                                          "Present" and
                                                          the Source PAN
                                                          ID field being
                                                          "Not Present".

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
I
                                                          propose the
                                                          following text
                                                          which I think
                                                          is aligned
                                                          with what has
                                                          been commented
                                                          during the
                                                          discussion.

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
The
                                                          IEEE802.15.4
                                                          header of all
                                                          frames MUST
                                                          include the
                                                          Sequence
                                                          Number field,
                                                          the Source
                                                          Address field
                                                          and the
                                                          Destination
                                                          Address field
                                                          and only the
                                                          Destination
                                                          PANID. Source
                                                          and
                                                          destination
                                                          address fields
                                                          MUST be filled
                                                          with an
                                                          extended
                                                          address (64
                                                          bit) and this
                                                          be indicated
                                                          in the
                                                          corresponding
                                                          Frame Control
                                                          field. In case
                                                          of a
                                                          destination
                                                          broadcast
                                                          address, the
                                                          address field
                                                          MUST be filled
                                                          by a short
                                                          addresses
                                                          (16bit). The
                                                          Destination
                                                          PANID MUST be
                                                          present and
                                                          the Source
                                                          PANID MUST be
                                                          elided.

                                                          

                                                          

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
Would
                                                          that work?

                                                          

                                                          

                                                          
 

                                                          

                                                          

                                                          
regards,

                                                          

                                                          

                                                          
Xavi

                                                          

                                                          

                                                          

                                                          

                                                          

                                                          
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