[Ndn-interest] Ndn clock synchronization requirements

Viktor S. Wold Eide viktor.s.wold.eide at gmail.com
Wed Jun 12 03:34:48 PDT 2019

Thanks for the follow up and viewpoints.

As written, the NDN Protocol design principles states universality
(including IoT and other highly constrained environments) and that the
core network protocol operations should not depend on clock
synchronization. Hence, I expected that to be the case.

During testing I experienced that NLSR did not work as expected
(although I'm not sure to what extent NLSR is considered core
protocol). To me, before starting to look more closely into it, the
system appeared brittle / faulty. I may have overlooked something, but
I did not see any log messages from the system indicating insufficient
clock synchronization or clock skew being outside acceptable

It appears reasonable, that if some parts of the NDN core systems
assumes clock synchronization to be within some specific boundaries,
it should be explicitly stated as a requirement. Additionally,
protocols / software should then also detect and handle
synchronization problems in a deterministic / predictable way, and not
silently fail or operate in unpredictable ways.

I wanted to ask here to clarify the NDN clock synchronization
requirements in general. From the design principle and your first
sentence, I would assume that your viewpoint is controversial. I
understand that your viewpoint is to require rather tight clock
synchronization, maybe even sub-second. That is currently contrary to
one of the listed main design principles of NDN.

To me then, the clock synchronization requirements in NDN appear
unclear / unresolved / in conflict :

- the design principles state that the core network protocol should
  not depend on clock synchronization.

- some NDN protocol / software (NLSR, other?) implementation appear to
  assume and depend on clock synchronization for correct operation.

Which other parts of NDN core system depend on clock synchronization?
In case, to what extent?

If and in case to what extent have the NDN protocols / implementations
moved away from the NDN design principle regarding clock

Are there any NDN "official" viewpoints on clock synchronization
requirements, which could indicate where this is heading protocol-wise and
implementation-wise in the near future?

Best regards
Viktor S. Wold Eide

More information about the Ndn-interest mailing list