Datagrams & Virtual Circuits скачать в хорошем качестве

Datagrams & Virtual Circuits

PDF link: https://tinyurl.com/yh9gqpdb or http://en.videolearner.com/index.php/... Want to buy me a cup of coffee? Click here! https://streamlabs.com/spyrosgeorgios Datagrams & Virtual Circuits The two packet switching methods As we have seen, when a station wants to send a message through a packet switched network, which is bigger than the maximum size of the packet that supports the network, breaks it into packets and sends them one by one to the network. So how the network will handle this packet flow, so that they can route them properly and finally deliver them to their destination. There are two methods of routing packets to a packet switched network: Datagrams and Virtual Circuits. Datagrams In the datagram(packet) method, each packet follows its own path into the network. Packet Routing selection depends on the number of Datagrams(packets) waiting to be processed at each node. Each time, the best (eg time shortest) route is selected. A simulation of packet movement within such a network is a school trip with more than one bus. Buses, depending on the traffic conditions, can follow a different route each,resulting in their destination in a different order from the one they started. Advantage of the method is to make better use of the network's physical channels (communication channels) and increased reliability due to the existence of alternative routes. Also, because no packing process is required for packet transmission, if a station wants to transmit only a few packages, these will be delivered sooner to their destination. Thus, packet switching with the Datagram method is ideal for short packet transmissions. Disadvantage is, it is likely that the packets need to be rearranged, because they may arrive at the recipient's node in a different order from the one with which they were sent. A typical example of a Datagram network was Internet (TCP / IP). Virtual Circuits In the virtual circuit method, before the packet transmission begins, the best PATH is selected. This path follows all the packets from the start and end of the connection. A simulation of the following networks we have in moving students to a school with buses, which follow the same path one behind the other. Advantage of the virtual circuit method versus the method of the datagram is the sorted receipt of packets, which means easy and without checks and delays transmission and RE-COMPOSITION of the message. Also, the switch node does not need to take complex routing decisions for each packet. These properties make the packet switching with virtual circuits ideal for fast transmissions of relatively long duration. Disadvantage is reduced reliability, since, if it breaks a node or if there is a congestion on some part of the network, it can not be easily reroute.