[Ndn-interest] Local hub discovery procedure
Muhammad Hosain Abdollahi Sabet
M.AbdollahiSabet at mail.sbu.ac.ir
Fri Feb 12 14:00:06 PST 2016
Firstly, thank you so much.
Secondly, how is auto-configure-server supposed to work then? This server should somehow receive interests for /localhop/ndn-autoconf/hub. While it's face uri is not on multiaccess faces list, I don't see how it is supposed to work. Actually I tested this. I mean I tried autoconfig-client side on a node which was configured for being autoconfig-server, and needless to say that I got error code 408. Am I to run some multicast capability in my home network to be able to use autoconfig client-server system?
Third, assuming the above issues have passed, if I poke for /localhop/nfd/rib/routable-prefixes, I(an application) should receive available prefix(es) for publishing data, right?
From: Alex Afanasyev [mailto:aa at cs.ucla.edu]
Sent: Sat 2/13/2016 1:05 AM
To: Muhammad Hosain Abdollahi Sabet
Cc: ndn-interest at lists.cs.ucla.edu
Subject: Re: [Ndn-interest] Local hub discovery procedure
> On Feb 12, 2016, at 9:35 AM, Muhammad Hosain Abdollahi Sabet <M.AbdollahiSabet at mail.sbu.ac.ir> wrote:
> Hello everyone,
> As far as I understood, according to:
> http://named-data.net/doc/NFD/current/misc/local-prefix-discovery.html <http://named-data.net/doc/NFD/current/misc/local-prefix-discovery.html>
> http://named-data.net/doc/NFD/current/manpages/ndn-autoconfig.htm <http://named-data.net/doc/NFD/current/manpages/ndn-autoconfig.htm>
> When I run ndn-autoconfig, NFD will send an interest to /localhop/ndn-autoconf/hub over a multicast face. After that assuming there is some autoconfig server behind one of the node's multiaccess faces, the node receives a data packet including the face uri of a localhub.
The above correctly describes the basic NDN-native procedure. Just to extend it, as you saw in the documentation, there are two additional stages to help with configuring IP-overlay NDN connectivity. While not yet formally defined, we are also planning to extend the stages to include discovery using mDNS/DNS-SD protocols (http://redmine.named-data.net/issues/3465 <http://redmine.named-data.net/issues/3465>). Anecdotally, mDNS queries have higher chances to work than other protocols, even though they utilize the same IP multicast.
> Then after registering /localhop/ prefix on the very face that it has got from the localhub, the node will again send an interest this time for /localhop/nfd/rib/routable-prefixes and awaits for a data packet including some prefixes which it(interest sender application) can register for publishing data.
Correct, but just to clarify. As of right now, "node" in this sentence is any NDN application that wants to obtain information about routable prefixes. There is an extension of this mechanism (http://redmine.named-data.net/issues/3145 <http://redmine.named-data.net/issues/3145>) in which local NFD will be expressing such interests.
> If I'm wrong some where, please correct me.
> Right now I have these two multiaccess faces:
> I know the former is IANA assigned, but I don't know the latter. My question are:
> 1- The reason my machine's NFD is not receiving anything form 220.127.116.11 is that this IP is not globally routable, and I don't have any autoconfig server in my local network having this IP and being up and running. Right?
18.104.22.168 is a multicast IP address and how far interests sent over such face will propagate depends on your networking environment (e.g., whether or not your WiFI access point allows multicast, whether you're running multicast routing protocol on your routers, etc.).
The shorter answer to your question is most likely yes. Not getting any reply most likely mean that you don't have NFD and associated autoconfig server running in your local network.
> 2- What is the second one? I've checked my host machine's virtual NICs(NFD is on a VM). It's not any of their MACs.
This is a multicast Ethernet address. It is not yet assigned, but it is effectively a mapping of 22.214.171.124 to ethernet address range (https://technet.microsoft.com/en-us/library/cc957928.aspx <https://technet.microsoft.com/en-us/library/cc957928.aspx>).
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