From: grahn+nntp@snipabacken.se   
      
   On Thu, 2015-09-24, bit-naughty@hotmail.com wrote:   
   > On Monday, September 21, 2015 at 10:29:09 PM UTC+5:30, Barry Margolin wrote:   
   >> 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.)   
   >   
   >   
   > OK, thanks. For the moment, could you just clear up 2 things for me...? :   
      
   > 1) Suppose I'm watching a Youtube video - it's true that different   
   > bytes of the same video could travel via different routes to get to   
   > me, right? Say, I'm in the UK, one byte could come straight from the   
   > US, and another via South America, say....? I mean, that's what TCP/IP   
   > does, right?   
      
   IP is designed so it /could/ happen, yes.  Not on the byte level but   
   on the IP packet level.  And an application or IP stack which cannot   
   cope with it happening is broken by definition, IMO.   
      
   I think it doesn't happen very often.  Especially spreading one data   
   flow over several routes has drawbacks, like packets arriving in the   
   wrong order, sudden MTU changes and so on.   
      
   Perhaps it's more common that packets A->B take a different path than   
   B->A does?  I'd be interested to hear about it from someone who knows   
   more about the topology as it looks today.   
      
   /Jorgen   
      
   --   
     // Jorgen Grahn    O  o   .   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)