Circuit switching:
Circuit switching is used in public telephone networks and is the basis for private networks built on leased-lines. Circuit switching was developed to handle voice traffic but also digital data (although inefficient) With circuit switching a dedicated path is established between two stations for communication Switching and transmission resources within the network are reserved for the exclusive use of the circuit for the duration of the connection The connection is transparent: once it is established, it appears to attached devices as if there were a direct connection Dedicated communication path between two stations Path is a connected sequence of links between network nodes Communication via circuit switching involves three phases:
— Circuit Establishment
— Data Transfer
— Circuit Disconnect Connection path must be established before data transmission begins Nodes must have switching capacity and channel capacity to establish connection
Packet switching:
Packet switching was designed to provide a more efficient facility than circuit-switching for bursty data traffic With packet switching, a station transmits data in small blocks, called packets Each packet contains some portion of the user data plus control info needed for proper functioning of the network
A key element of packet-switching networks is whether the internal operation is datagram or virtual circuit (VC).
— With internal VCs, a route is defined between two endpoints and all packets for that VC follow the same route
— With internal diagrams, each packet is treated independently, and packets intended for the same destination may follow different routes Examples of packet switching networks are X.25, Frame Relay, ATM and IP.
No comments:
Post a Comment