Subject: [dtn] draft-ietf-dtn-bibect-03 issues

From: [email-masked]
Date: Fri, 21 May 2021 10:54:34 +0200

Hi,

I have spotted two issues in draft 3 of the Bundle-In-Bundle 
Encapsulation:

1)  Custodial Transmission Count

The CTC is defined in 3.2 as:

     1. A "custodial transmission count" (CTC).  A CTC is a
        monotonically increasing integer indicating the number of
        custodial BPDUs that have been issued to this BIBE node by the
        local node since instantiation of the local node.

a) To have the CTC as the number of BPDUs since the instantiation of the 
local node might be problematic in cases where the local node is 
re-started because the CTC is later used as 'Transmission ID' which should 
be unique over some time frame.

b) In the definition above, the CTC is defined per custodial node. 
However, later it is stated:

"The transmission ID for a BPDU for which custody transfer IS
   requested SHALL be the current value of the local node's custodial
   transmission count, plus 1."

To me, this seems to indicate a single CTC per local node.

Scott confirmed that the first interpretation is correct (one CTC per 
custodial node), so this text should be updated. It may still make sense 
to require increasing of the transmission id by 'plus 1' only as this 
allows more efficient custody signals.

2) Section 3.4 defines:

A  "custody transfer status report" is a bundle status report with the 
"reporting node attempted custody transfer" flag set to 1. 

This flag and issuing this status report is described nowhere. I assume 
this section should be removed.

Regards,
Felix

_________________________________________
ESA - European Space Agency 
Dr. Felix Flentge
Software Engineer, OPS-GSB
Ground Systems Engineering Department
Directorate of Operations
ESA - ESOC
Robert-Bosch-Str.5, D-64293 Darmstadt, Germany
Phone: +49 6151 90 4075 | Email: [email-masked]
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