packet switching vs message switching | difference between packet switching and message switching

This page packet switching vs message switching covers difference between packet switching and message switching. The difference between circuit switching and packet switching link is also mentioned.

Before we dig into packet switching vs message switching, I suggest one to go through circuit switching vs packet switching. Let us take example of data communication between source machine and destination machine with 3 routers in between. There may be more number of routers between them.

Message Switching

Figure-1 depicts message switching operation. As shown in the figure, each router waits until it receives the entire message. Once it receives the complete message it transmits the same over the next link and so on. All the routers over the router does the same.

In a message switching Total time for Transmitting a message =
L*tPROP + L*T = L*tPROP + L*(k*P)
Where in,
L = Number of Hops
tPROP = propagation delay per hop
k = Number of packets which represent each message
P = time for transmitting each packet
T = time for transmitting complete message = k*P

Packet Switching

Packet switching is basically a special case of message switching type. After advancement of computer communication and networking, packet switching came into existence.

In packet switching, the message is broken into smaller pieces. This will allow each router to start transmission as soon as first packet of message has been arrived. This will save enormous amount of time, especially when no. of hops between source and destination are more. Hence propagation delay is more here. The same has been depicted in figure-2.

In packet switching, Total time for Transmitting a message =
L*tPROP + L*P + (k -1)*P

Comparison or difference between packet switching and message switching

Let us summarize comparison factors as difference between packet switching and message switching networks.

➨ Message switching overhead is lower compare to packet switching. Fig-3 depicts that single datagram is transmitted in message switching. As mentioned, message is appended with header before transmission. In packet switching message is divided into smaller packets amd each packet is appended with header before transmission.
Where, n = [message/packet_size]

➨ Message switching has higher reliability and lower complexity. As in message switching, one single datagram is either received or lost. One single network path is used for the same.

In packet switching, many packets generated by same node and belonging to the same destination may take different paths. The packets received out of order will need to be sequenced using sequence number embedded in the header part. May lose or corrupt a subset of the message but do not discard the entire message as in message switching. Hence based on overall corrupt message received, what could be correct message can be interpreted. Due to this reason, sometimes in the real time scenarios such as voice, message switching is not possible.

➨As explained above message switching takes more time compare to packet switching as entire message will be stored at each of the hop points till it is completely received.