A packet sniffer can also be used on the internet to capture data traveling between computers. Internet packets often have very long distances to travel, passing through several routers that act like intermediate post offices. A packet sniffer might be installed at any point along the way. It could also be clandestinely installed on a server that acts as a gateway or collects vital personal information.
A packet sniffer is not just a hacker's tool. It can be used for network troubleshooting and other useful purposes. However, in the wrong hands, a packet sniffer can capture sensitive personal information that can lead to invasion of privacy, identity theft, and other serious eventualities.
Advantages:-
Economical (Resource Sharing)
Fault Tolerant
Prioritization (Is Possible)
Disadvantages:-
Transmission Time
Waiting Time.
Total Delay{ Transmission Time + Waiting Time}
NOTE:- According to the disadvantages of datgram networks those delays are w.r.t One packet
An advantage of packet switching is that a large amount of data can be sent at one time over the network. A big disadvantage of packet switching is the during the data transfer some of the files might get lost in the transfer.
Datagram Packet Switching
1. Datagram circuits allow packets to contains full address instead of circuit number so each packet has significant amount of overhead, and hence wasted band width. Thus it is costly.
2. Datagram circuit does not require setup phase , so no resources are consumed.
3. In datagram circuit, a more complicated procedure is required to determine where the packet goes.
4. In a datagram subnet, congestion avoidance is more difficult.
5. In datagram circuit if a router goes down only those user whose packets were queued up in the router at the time will suffer.
6. The loss or fault on communication line can be easily compensated in datagram circuits.
7. Datagram allow the router to balance the traffic throughout the subnet, since router can be changed halfway through a connection.
Circuit switching.
Packet switching has two advantages: (1) If something goes wrong, only a small piece of data (the packet) has to be resent. (2) Packet switching allows multiplexing - several communications happening at once.Packet switching has two advantages: (1) If something goes wrong, only a small piece of data (the packet) has to be resent. (2) Packet switching allows multiplexing - several communications happening at once.Packet switching has two advantages: (1) If something goes wrong, only a small piece of data (the packet) has to be resent. (2) Packet switching allows multiplexing - several communications happening at once.Packet switching has two advantages: (1) If something goes wrong, only a small piece of data (the packet) has to be resent. (2) Packet switching allows multiplexing - several communications happening at once.
A PDU (Protocol Data Unit) is defined by which layer it is in. In the physical layer and network layer, it is synonymous with the packet, in the data link layer, it is the frame. In the transport layer, it is a datagram for UDP. A datagram holds one or more PDU's, as it is the basic unit of transferring information via packet switching.
IP Datagram
A datagram or packet needs to be self-contained without reliance on earlier exchanges because there is no connection of fixed duration between the two communicating points as there is, for example, in most voice telephone conversations.
packet switching is use today
packet switching circuit switching message switching
Packet Switching =)
Packet Switching - Computer Communications (Digital)Circuit Switching was used for old fashioned telephony. At present, many companies use VOIP (Packet Switching) for voice communications.
Data transfer will be faster in packet switching providing the setup time in circuit switching is greater than the time required to send a packet. If not, that is setup time in circuit switching takes less time, then circuit switching is quicker.
In circuit switching there is also some required overhead; the overhead in packet switching is usually a small percentage of the total traffic; and in any case, the benefits of packet switching far outweigh any disadvantage of some minor overhead.
1. circuit switching 2. packet switching