Broadcast

In computer networking a broadcast refers to a transmission to all interface cards on a network subnet. RFC 919 and RFC 922 describe IP broadcast datagrams. There are two types of broadcasts:

  1. Limited Broadcast - Sent to all NICs on the some network segment as the source NIC. It is represented with the 255.255.255.255 TCP/IP address. This broadcast is not forwarded by routers so will only appear on one network segment.
  2. Direct broadcast - Sent to all hosts on a network. Routers may be configured to forward directed broadcasts on large networks. For network 192.168.0.0, the broadcast is 192.168.255.255.

Situations where broadcasting are used include:

  • ARP on IP
  • DHCP on IP
  • Routing table updates. Broadcasts sent by routers with routing table updates to other routers.