Project

General

Profile

HubDiscovery » History » Revision 3

Revision 1 (Alex Afanasyev, 01/31/2014 10:41 PM) → Revision 3/8 (Junxiao Shi, 02/27/2014 08:41 AM)

# NDN hub discovery procedure 
 =========================== 

 When an end host starts up, or detects a change in its network environment, it MAY use this procedure to discover a local or home NDN router, in order to gain connectivity to [the NDN research testbed](http://named-data.net/ndn-testbed/). 

 ## Overview 

 This procedure contains three methods to discover a NDN router: 

 1.    Look Add multicast face, issue interest for a local NDN router by multicast.   
     This is useful in a home or small office network. 
 2.    Look for a local NDN router by DNS query with default suffix.   
     This allows network administrator to ``/local/ndn/udp`` 

     *     if data returned, configure a NDN router for a large enterprise network. 
 3.    Connect face to the home NDN router according hub and finish auto-config 

     *     auto-configured face is remembered using creating a "fake" route to user certificate.   
     This ensures connectivity from anywhere. ``/autoconf`` prefix 

 ## Stage 1: multicast discovery 

 ### Request 

 The end host sends an Interest over a multicast face. 

 Interest Name is `/localhop/ndn-autoconf/hub`. 

 ### Response 

 A producer app on 2. If previous step failed, issue the HUB answer this Interest with a Data packet that contains TLV-encoded `Uri` block. 
 The value of this block is the URI for the HUB, preferrably a UDP tunnel. 

 ## Stage 2: following DNS query with default suffix 

 ### Request 

 The end host sends a DNS query that is equivalent to this command: 

     using dig command  

         dig +search +short +cmd +tries=2 +ndots=10 _ndn._udp _nfd._udp srv 

 ### Response 

 The DNS server should answer with an SRV record that contains 

     *     if valid data returned, get the hostname first returned data, configure face, and UDP port number finish auto-config 

     *     auto-configured face is remembered using creating a "fake" route to /autoconf prefix 

 3. If previous steps failed: 

     *     Obtain name of the NDN router. 

 ## Stage 3: find home router 

 ### Request 

 The end host loads the default certificate of configured for the user, extracts the user 

     *     Try to extract site-specific part from the certificate name. 

 The end host sends a DNS query for an SRV record of name `_ndn._udp.` + site-specific part + `_homehub._autoconf.named-data.net`. 

 ### Response 

 The DNS server should answer with an SRV record that contains the hostname and UDP port number of the home NDN router of this user's site. 

 ## Client procedure 

 1. (TBD).    Send a multicast discovery Interest. 
     If this Interest got answered, connect to the HUB and failed, abort these steps. 
 2.    Send a DNS query with default suffix. 
     If this query got answered, connect auto-configuration step. 

     *     Append ``_homehub._autoconf.named-data.net.`` postfix to the HUB and abort these steps. 
 3.    Extract the site-specific part from the default certificate of the user; fail if this cannot complete. 
     Send DNSified name, e.g. 

             alex.ucla.edu._homehub._autoconf.named-data.net. 

     *     Issue a DNS SRV dns query to find home HUB. 
     If this query got answered, connect to the home HUB. Otherwise, fail. with ``_ndnx._udp`` prefix (not really necessary, but should do it for clarity)