Broadcast networks have a single communication channel which is shared by all the machines on the network. Here messages are broken into packets which are then broadcast to all machines in the chanel. A packet sent by any machine is received by all the machines but only that machine processes the packet for which it is intended. An address field, within the packet specifies for whome it is intended. Upon receiving a packet, a machine checks the packet, if it is intended for some other machine, it is just ignored. However, in broadcast networks, we have the problem of deciding who uses thechanel, if there is competition for it. For this medium access control (MAC) is used to determine who gose next.
As an analogy, let us imagine a scenario where a teacher taking the attendance in a particular class. He/she will cll every roll number in the classroom, all will listen but only the respective student will respond. Broadcast implies “sending a signal where multiple parties may hear a signal sender”
Again, let us imagine a scenario that a teacher is taking the attendance in an examination hall. He/she will go to each member of the room and will take the attendance individually. Here only one person listen and he only respond to the call. Point-to-point network is a method of communication where one “point” speaks to another entity. Point-to-point network consist of many connections between individual pairs of machines. Packet, on this type of network, may have to visit one or more intermediate machines to reach from the source to the destination. Often multiple routes of different lengths are possible in point-to-point networks. Therefore, routing algorithms are required to determine the best routes out of multiple available routes.