[Cesg-all] Re: Rick Schnurr's comments re: AOS Pink Sheets

[Takahiro Yamada]

Adrian and all,

Sorry for my late response. I will submit formal RIDs against the Pink 
Sheets but here are quick answers to some of the concerns.

The proposed extension is very similar to the modulo-128 option of HDLC 
(the normal mode is modulo-8) and therefore I support it provided that 
(1) it is optional and (2) there are missions that need it.

> But how does the receiver know whether this field is used or not? 
> Whichever way you look at it, you're running a different protocol with a 
> 24-bit counter than you are with a 27-bit counter. Different protocols 
> are normally signalled to the receiver. How is the signalling done in 
> your proposal?

The AOS receiver has to know several things before being able to receive 
  frames (for example, frame length). Therefore, I think the counter 
length can be a managed parameter (like the frame length). And it must 
be registered in section 5.5 of the Blue Book.

>> This would also benefit missions flying SSRs using AOS frame 
>> retransmission.
> 
> No doubt. But then why don't you package this change as part of an 
> omnibus proposal that adds the AOS retransmission procedures *and* the 
> capability to handle higher data rates? 

I would prefer to specify the extended counter length separately from 
the proposed retransmission procedure because AOS can, in principle, 
have multiple retransmission procedures. (TCP has multiple 
retransmission procedures including the SNACK defined by SCPS-TP.)

Best regards,
Takahiro Yamada, ISAS.