Re: [dtn] [EXTERNAL] Alexey Melnikov's Discuss on draft-ietf-dtn-bpbis-22: (with DISCUSS and COMMENT)

["Alexey Melnikov" <[e-mail]>]

Hi Scott,
Quickly replying to a single issue:

On Sat, Feb 8, 2020, at 12:45 AM, Burleigh, Scott C (US 312B) wrote:
> > ## Section 5.8
> > 
> > Clarity: The insistence, here and earlier, that a bundle is only 
> > fragmented into two packets, and that this can then be performed 
> > recursively, seems unhelpful.  Bundles can be fragmented into 
> > arbitrarily many pieces, and this binary subdivision concept is not 
> > actually present in the protocol.  I suggest removing it from the text 
> > as well.
> > 
> > 		Why is this unhelpful?  It's the formal procedure by which bundles 
> > are fragmented.  Let's not remove it.
> 
> I think saying that a bundle can only be fragmented into 2 pieces is a 
> lie, because the algorithm says that it can be fragmented into more 
> than 2. I found this text to be confusing as well. Just say that it can 
> be fragmented into 2 or more non overlapping fragments.
> 
> 	***	It is absolutely not a lie.  A bundle can be fragmented into 
> exactly 2 pieces, each of which is a bundle.  There is no defined 
> mechanism for fragmenting a single 		bundle into 3 pieces, or 4, other 
> than the recursive exercise of the binary fragmentation mechanism 
> defined in detail in section 5.8.  But I will try to make this 
> 		clearer in the text.

Think of it from the point of view of a receiving system: if there were several nodes before it, it can't rely on only being 2 fragments, it has to expect arbitrary number of them.

So the text you have is possibly helpful for the sending system, but not for the receiving one.

Best Regards,
Alexey