[Ndn-interest] Network inconsistency and NLSR sequence numbers

[Junxiao Shi]

Hi Viktor

This is a known problem. NLSR uses three "sequencing files" to record last
sequence numbers across restarts https://redmine.named-data.net/issues/1523
. You are supposed to backup and restore these files if you reimage a node,
as part of provisioning process.

I wonder what's NLSR developer's suggestion if a node experienced an
unrecoverable disk failure. NLSR could have inserted a random UUID to its
own name every time it's launched, so that sequencing files are no longer
necessary. Alternatively, we'll need some tools to query the network and
recover sequencing files based on knowledge of other nodes in the network.

Yours, Junxiao

On Thu, Aug 22, 2019, 06:19 Viktor S. Wold Eide via Ndn-interest <
ndn-interest at lists.cs.ucla.edu> wrote:

> Dear list members,
>
> There seems to be some issues regarding nlsr and sequence
> numbers. This is for nlsr version NLSR-0.5.0.
>
> Sorry if I overlooked something that is already well explained.
>
> I have a number of ndn nodes all running nlsr and everything seems to
> work well. Then after some time (days / hours) i completely wipe the
> disk of one of the nodes and then reinstall the node, including the
> operating system, all applications, and importantly here also ndn and
> nlsr. Note that the node is re-installed with the same name as before,
> also ndn / nlsr-wise.
>
> Now, all the other nodes ignore the re-installed node. From what I can
> see, they request name LSA and adjacent LSA information from the
> re-installed node using sequence numbers from before the
> re-install. However, the re-installed node got its sequence numbers
> reset as part of the re-install. Hence, the re-installed node does not
> seem to become part of the ndn network.
>
> Assuming that I have not misunderstood something and this is the way
> it actually behaves and works, the question is then how is this
> supposed to be handled?
>
> Keeping track of sequence numbers across re-install is hopefully not
> an answer. I would expect that nodes must forget / delete / reset
> knowledge of other nodes in some cases, and at least after some time.
>
> What are the steps required to get everything working again?
>
>
> Best regards
> Viktor S. Wold Eide
>
>
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