Why not multicasting?

• IP Multicasting is utilized for messaging in LANs, but not for Internet-scale
  
  
• Multicasting groups manageability problems
  • Limited availability
  • Dynamic creation still not practicable
    
    
• No authentication, no access control
  
  
• Unreliable protocols without congestion control
  
  
• Application layer multicasting addresses these problems. No support for Quality-of-Service parameters.