[core] CoAP message aggregation (over BP, and perhaps other transports)

Carles Gomez Montenegro <carles.gomez@upc.edu> Tue, 18 June 2024 09:29 UTC

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From: Carles Gomez Montenegro <carles.gomez@upc.edu>
Date: Tue, 18 Jun 2024 11:29:01 +0200
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Subject: [core] CoAP message aggregation (over BP, and perhaps other transports)
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Dear CoRE WG,

(DTN WG in CC.)

In IETF 119, while presenting the CoAP over BP draft [1] in the DTN WG
session, the idea of aggregating several CoAP messages over a single bundle
was suggested by Joshua Deaton (thanks!). As long as the additional
aggregation delay can be tolerated, the idea can be useful to reduce
protocol overhead.

If there is interest to support CoAP message aggregation over BP, perhaps a
more general mechanism, not necessarily dependent on BP, might be
interesting, as it might be used over other transports (e.g., UDP) as well.

One way to enable CoAP message aggregation over BP would be the approach in
Appendix A.2 of [2], which (in the context of CoAP message aggregation over
UDP) proposes using a new CoAP option, called Payload-Length option, to
delimit the payload of each aggregated message.

Some time ago, there was an initiative to define such an option [3].
However, it appears that the work was not completed. Not sure if there has
been any similar initiative since then.

What would be your thoughts about reprising work such as [3] and/or
enabling CoAP message aggregation over several possible transports?

Many thanks in advance.

Cheers,

Carles and Anna

[1] https://datatracker.ietf.org/doc/draft-gomez-core-coap-bp
[2] https://www.ietf.org/archive/id/draft-bormann-coap-misc-27.txt
[3]
https://datatracker.ietf.org/doc/draft-li-core-coap-payload-length-option