[Ndn-interest] Issues in routing
klaus at cs.arizona.edu
Mon Nov 19 09:38:10 PST 2018
I think it's useful to distinguish between 3 logical entities:
1. Router -- forwards packets towards a storage location
2. Content Store -- a temporary storage location (can be cleared at any
3. Content Repository -- a permanent storage location (in the same sense
as today's web servers are "permanent")
These can all be on the same machine or on a different machine. For
example, a core NDN router will probably have a content store, but not a
Now to answer your questions:
> So, if a router is down for some reason, what about the data it
>> stores in its CS and the connections it hold?
Well, the content store will be unreachable. There is usually no notion
of a "connection" in NDN, so other routers should be able to fetch the
data from somewhere else.
> If the router is
>> temporarily down, it can resume to its normal operations sometime
Sure. Why not?
> But if the router is permanently down and there are several data
>> it produce and there are no more copies of all the data.
That only matters if the last content repository is down. In this case
the data might become unavailable, if all the content stores have
cleared the data as well (which they are free to do).
NDN does not have the goal to permanently replicate every content piece
inside the network. The content provider is still responsible for
keeping their content repository up and running, and likely wants to
provide some redundancy here.
NDN, however, can help with the scalability: it reduces the load on the
content repository when its content objects become more popular.
On 11/19/18 2:32 AM, Tanusree Chatterjee wrote:
> Hello all,
> In NDN the routers are the busiest and most responsible entity in the
> network. So, if a router is down for some reason, what about the data it
> stores in its CS and the connections it hold? If the router is
> temporarily down, it can resume to its normal operations sometime
> later. But if the router is permanently down and there are several data
> it produce and there are no more copies of all the data. Can there be
> any network administrator which can have the copies of the data of a
> router when it is down? If it is a high connectivity node, can network
> administrator can play a vital roll to take care the connections of the
> -- Thanks & Regards,
> Tanusree Chatterjee
> Ndn-interest mailing list
> Ndn-interest at lists.cs.ucla.edu
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