System information

IP Multicast
Book Title
7-100
Figure 7-9 Packet Flow in UDP Flooding
Subnet Broadcast
Subnet broadcast (defined in RFC 922) supports the sending of packets to all the subnets of a
particular network number. Packet duplication occurs when there are alternative paths in a network.
In Figure 7-10, when Workstation A uses subnet broadcasting to send a packet to each workstation
on Subnetwork 2, a duplicate packet also arrives.
Figure 7-10 Subnet Broadcast
Workstation A
UDP packets
Interfaces are in
blocking state
Interfaces are in
forwarding state
Subnetwork 1
Workstation B
Workstation C
Subnetwork 2
Workstation D
Subnetwork 3
Router Router
Version
Identification Flags Fragment offset
Time-to-live Protocol Header checksum
Source address
32 bits
Destination address
Options (+ padding)
Data (variable)
Type-of-service Total lengthIHL