IP Multicasting (2)

IP addresses in the range 224.0.0.0 through 239.255.255.255 are designated as multicast addresses

• The 224.*.*.* addresses are reserved for use by the management protocols on a LAN,

• 225.*.*.* and 232.*.*.* addresses are IANA assigned addresses

  • IANA : Internet Assigned Number Authority

• Packets sent to the 239.*.*.* addresses are typically only sent to hosts within a single organisation

• Internet-based net-VE application should therefore use one or more random addresses in the 225.*.*.* to 231.*.*.* and 233.*.*.* to 238.*.*.* range

The sender transmits data to a multicast IP address, and a subscriber receives the packet if it has explicitly joined that address

Each Multicast IP address is connected to a multicast distribution tree built by the network

To chose a free Multicast address...

• Listen to the SAP (Session Announcement Protocol)

• Chose an unused address and announce it using SDP (Session Description Protocol) to describe it

• Or use the SDR (Session Directory)