[Sis-dtn] Fragmentation in BPv7 Orange Book

[Lars Baumgaertner]

While looking through the PICS tests in the latest BPv7 OB draft, I was a bit confused about the handling of fragmentation in the light of the most recent discussions.


[cid:image001.png at 01DBE788.3FFDAE80]

Fragmentation itself is OPTIONAL in #31.
#32 is CONDITIONAL as it only makes sense if #31 is implemented.
#34 is OPTIONAL, so BPAs can choose to do on-path ADU reassembly.

But #33 is MANDATORY, meaning EVERY BPA must support ADU reassembly.
So even if we forbid fragmentation, and the feature at the source node is optional, all BPA that want to be compliant must still implement ADU reassembly logic and act upon it at the receiving end. This is quite a burden, increases attack surface and just seems unnecessary for an optional feature and something which might be forbidden per policy in most deployments anyhow.

Wouldn't it make sense to make this OPTIONAL as well since consensus now seems to be not to do fragmentation at all (at least in the short to mid term)?
One could also read the feature description as IF/WHEN doing reassembly (which itself is optional) it should then follow the rfc procedures, but then it would be CONDITIONAL, right?
Or maybe there is another way to read #33 that I missed...

Kind regards and have a nice weekend,
Lars

--
Lars Baumgaertner
Internal Research Fellow (OPS-GAE)
European Space Agency ESA/ESOC
Robert-Bosch-Str. 5, D-64293 Darmstadt

This message is intended only for the recipient(s) named above. It may contain proprietary information and/or protected content. Any unauthorised disclosure, use, retention or dissemination is prohibited. If you have received this e-mail in error, please notify the sender immediately. ESA applies appropriate organisational measures to protect personal data, in case of data privacy queries, please contact the ESA Data Protection Officer (dpo at esa.int).
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.ccsds.org/pipermail/sis-dtn/attachments/20250627/b19dc1eb/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 32107 bytes
Desc: image001.png
URL: <http://mailman.ccsds.org/pipermail/sis-dtn/attachments/20250627/b19dc1eb/attachment-0001.png>