[Ndn-interest] Issues in routing

[Tanusree Chatterjee]

Hello Klaus,

Thank you. It cleared my doubts to some extent. But, you said that there is
no notion of connection in NDN and I did not understand what does it
exactly mean.
The nfd connection states that after installing NFD in a client machine,
we can specify the IP address and port number of the remote NFD, so that
NDN packets get encapsulated into UDP or TCP packets and sent to the remote
NFD. e.g. nfdc create udp4://192.0.2.1:6363  states the client machine
wants to establish a connection with 192.0.2.1:6363. Also as Junaxio's
explained in my last email answer that NDN-FCH service tells us the IP of
the routers near by. However, here I am a bit confused why there is no
notion of a connection. As my previous question was when a new ndn node
wants to enter in an existing network and establish a connection with a
node of the network, it does the above thing, isn't it? Please tell me if I
understood anything wrong.

Thanks & Regards,
Tanusree Chatterjee
On Nov 19, 2018 11:08 PM, "Klaus Schneider" <klaus at cs.arizona.edu> wrote:

> Hey Tanusree,
>
> 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
> time)
> 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
> content repository.
>
> 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 later
>>>
>>
> 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.
>
>
> Best regards,
> Klaus
>
>
>
> 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 nodes?
>>
>> -- Thanks & Regards,
>> Tanusree Chatterjee
>>
>>
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