Clients and servers that communicate via a perfect channel have a dedicated point-to-point channel between themselves (or at least the illusion of one). To communicate, they must first establish the connection, transmit the data, and then close down the connection. All data sent over the channel is received in the same order that it was sent. This is guaranteed by the channel. In contrast, clients and servers that communicate via datagrams send and receive completely independent packets. These clients and servers do not have a dedicated point-to-point channel. Rather the packets are sent on their way over the network on whatever route is available.
A packet sent over a perfect channel does not contain any information about its source or its destination. The channel contains that information. In contrast, a datagram packet must contain the complete address of its source or destination (depending on if the datagram is sent or received).
Definition: A datagram is an independent, self-contained message sent over the network whose arrival, arrival time, and content are not guaranteed.
The java.net package contains two classes to help you write Java programs that use the datagram model to send and receive packets over the network: DatagramSocket and DatagramPacket. A DatagramSocket is a communcation link used to send datagrams between applications. A DatagramPacket is a message sent between applications via a DatagramSocket.
Datagram is a packet which contains destonation address in it(complusorily) datagram network means connection-less network..i.e packets are forwarded with out establishing a circuit like in virtual circuit switching networks.
Refer to : A.s Tanenbaum COmputer networks(can be downloaded from pdfdatabse.com)
Computer networks by Larry L Peterson
A packet transport mode where packets are routed independently and may follow different paths, thus there is no guarantee of sequence delivery.
datagram is used in conectionless n/w e.g. UDP Whereas packets used in connection oriented n/w e.g. ATM X.25 tcp
Data is transmitted on a network in pieces called packets, datagrams, or frames. Specifically, the frame is the header and trailer surrounding the data. The entire header, trailer, and data is called the packet or datagram. A token is a small packet used on Token Ring or FDDI networks. The token is passed from node to node to indicate to the node that data can be sent on the network.
The Differentiated Services Field.
There are two address fields. Source is the IP address the packet came from and destination is the IP address the packet is meant to be delivered to.
datagram subnet is connection oriented network.
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.
Differentiated Services Field
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.
Circuit switching.
datagram is used in conectionless n/w e.g. UDP Whereas packets used in connection oriented n/w e.g. ATM X.25 tcp
what happens to a packet if the TTL field reaches 0 I dont believe a datagram reaches O because once the datagram reaches 1 the router or device discards it.I banged ur mom she sucked this stick B-----D
what happens to a packet if the TTL field reaches 0 I dont believe a datagram reaches O because once the datagram reaches 1 the router or device discards it.I banged ur mom she sucked this stick B-----D
Data is transmitted on a network in pieces called packets, datagrams, or frames. Specifically, the frame is the header and trailer surrounding the data. The entire header, trailer, and data is called the packet or datagram. A token is a small packet used on Token Ring or FDDI networks. The token is passed from node to node to indicate to the node that data can be sent on the network.
The Differentiated Services Field.
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.
To match the packet to the process that sent it.