[Ndn-interest] Network inconsistency and NLSR sequence numbers

Viktor S. Wold Eide viktor.s.wold.eide at gmail.com
Mon Aug 26 02:18:11 PDT 2019

On Sat, Aug 24, 2019 at 7:36 AM WENTAO SHANG <wentaoshang at ucla.edu> wrote:
> On Fri, Aug 23, 2019 at 5:38 AM Viktor S. Wold Eide <viktor.s.wold.eide at gmail.com> wrote:
>> Thanks a lot everyone for answers with information and suggestions.
>> I'll try to summarize my understanding so far. Please let me know if
>> this is (entirely) correct or not.
>> There are at least three main issues which currently make testing and
>> use of nlsr in a dynamic environment hard / difficult and also
>> inefficient network-wise.
> Link state routing is bad for dynamic environment in general. You would want something like AODV in those use cases.

I certainly would like to also have routing that is more geared towards
dynamic environments. Are there any implementations for Ndn which you
would recommend that I try out?


>> - nlsr requires periodic global synchronized re-start (stop, wait,
>>   start) of all nlsr instances in a network, to get rid of old
>>   information in nlsr / sync. (nfd can be left running during re-start
>>   of nlsr).
> Where did you get this conclusion from?

>From own observations, the other answers here, as well as the links
provided by Junxiao Shi and Ashlesh Gawande.

Do you know of another way to get rid of information in nlsr/sync,
that is, information from other nodes that are no longer connected to
the Ndn network?

>> - nlsr requires synchronized clocks, that is, global time for correct
>>   operation. (nfd does not seem to require global synchronized
>>   clocks).
> Why?

See another email thread with subject "Ndn clock synchronization
requirements" from June 11. 2019. Shortly, from testing I did see that
clock synchronization is required for nlsr to operate correctly. Name
LSA and adjacent LSA information is ignored when clocks in different
nodes are to far apart. The LSA information received by a node seem
to contain a timestamp set at the sender side. However, the receiver
uses its own local clock to determine if the LSA information is
outdated or not, which clearly does not work when clocks in different
nodes are not sufficiently synchronized.

Hence, I wrote that nlsr requires synchronized clocks, global time for
correct operation. I have not seen anything so far which indicate that
nfd itself require synchronized clocks.

Do you have any other information or do you see it differently?

Best regards
Viktor S. Wold Eide

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