Subject: [rohc] Query regarding Additional Mode transition logic for IR & IR-Dyn Packets (Interoperabilty)

From: "Chaitanya Pradeep" <[email-masked]>
Date: Tue, 17 Mar 2009 11:48:33 +0530

Dear RoHC ers,

     I am facing ambiguity regarding handling of Mode Cancellation for IR &
IR-Dyn Packets in Profile -0x0004 (RFC 3843).
     RFC 3843 says:

        The Mode parameter for  the value mode = 0 (packet types UOR-2, IR
and IR-DYN) is redefined
        to allow the compressor to decline a mode transition requested by
the decompressor:

        Mode: Compression mode.  0 = (C)ancel Mode Transition

  Upon receiving the Mode parameter set to '0', the decompressor MUST stay
in its current mode of operation and
       SHOULD refrain from sending  further mode transition requests for the
declined mode for a certain amount of time.

Q.1) How do we communicate mode parameter (i.e, '0' for Mode cancellation)
to Decompressor for IR & IR-Dyn Packets?

       RFC 3095/ 3843 has not defined any field indicating 'Mode' in IR
/IR-Dyn Packet formats for Profile-0x0004.
       But UOR-2 Packet can communicate mode value in the form of
Extension-3.

Q.2) Is this interpretation correct?

      Can we define a field for mode parameter in Dynamic chain (in IR &
IR-Dyn packets) and communicate the mode value
      to De-compressor, by indicating it as '0' for handling of Mode
Cancellation.

      Will the above implementation give any impact in Interoperabilty?

  Pls share your valuble thoughts regarding the same.

Thanks,
Pradeep.

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From: Carl Knutsson <[email-masked]>
Date: Tue, 17 Mar 2009 09:50:17 +0100

Pradeep, Ghyslain, L-E,

Even though it is confusing with the references to packet types (IR &
IR-DYN), I believe the mode transfer logic/cancel still works in RFC.

All references are refer to the mode field or the "mode field" & "packet
type" tuple. The text is very clear that the mode field needed
acknowledge Mode Transitions/Cancel. There are no mode fields in the IR
and IR-DYN packets. Mode Transfer/Mode Cancel can only be done with
UOR2-Ext3.

Best Regards,

Carl Knutsson

Chaitanya Pradeep wrote:
> Dear RoHC ers,
>  
>      I am facing ambiguity regarding handling of Mode Cancellation for
> IR & IR-Dyn Packets in Profile -0x0004 (RFC 3843).
>      RFC 3843 says:       
>     
>         The Mode parameter for  the value mode = 0 (packet types UOR-2,
> IR and IR-DYN) is redefined 
>         to allow the compressor to decline a mode transition requested
> by the decompressor:
>  
>      Upon receiving the Mode parameter set to '0', the decompressor MUST
> stay in its current mode of operation and
>        SHOULD refrain from sending  further mode transition requests for
> the declined mode for a certain amount of time.
> Q.1) How do we communicate mode parameter (i.e, '0' for Mode
> cancellation)  to Decompressor for IR & IR-Dyn Packets?
>