From: barmar@alum.mit.edu   
      
   In article <2a24a8dd-5ae8-4796-b66b-691088422964@googlegroups.com>,   
    bit-naughty@hotmail.com wrote:   
      
   > On Friday, September 18, 2015 at 7:47:58 AM UTC+5:30, Barry Margolin wrote:   
   > > In article ,   
   > >  b@hotmail.com wrote:   
   > >   
   > > > Hi,   
   > > > If a new ISP starts up,it has to be allocated IP addresses, right? What   
   > > > does   
   > > > this mean? What exactly is this step of "allocating", and who does it?   
   > >   
   > > They contact a Regional Internet Registry and purchase an IP block. For   
   > > instance, in North America they get it from ARIN, American Registry for   
   > > Internet Numbers.   
   > >   
   >   
   > But I thought nobody was in charge of the internet....? If ARIN dislikes   
   > someone, and refuses to give them any IPs, then what happens....?   
      
   If they don't meet the requirements to get IPs directly from ARIN (or   
   some other RIR), perhaps because they're too small, they purchase a   
   connection from a larger ISP. The ISP then assigns them a portion of   
   their own address block.   
      
   >   
   > > > How and when does that address become routable to? I'm no expert on   
   > > > internet   
   > > > routing, but it's based on graph theory, right?   
   > >   
   > > They establish connections to other ISPs, and advertise their address   
   > > blocks using BGP, the Border Gateway Protocol.   
   > >   
   >   
   > What does this do? Could you just give me a short overview....? I'd prefer   
   > that to Wikipedia or whatever... :)   
      
   BGP is how ISPs learn the address blocks that belong to each other. ISP1   
   tells ISP2 "I have a route for 50.60.128.0/15". ISP2 merges that with   
   all the routing advertisements it has received from other ISPs, and uses   
   that when deciding where to send traffic. (This is an extreme   
   simplification, read the Wikipedia article on BGP for more details.)   
      
   --   
   Barry Margolin   
   Arlington, MA   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)