Connectionless and connection-oriented packet switching
The service actually provided to the user by networks using packet switching nodes can be either be connectionless (based on datagram messages), or virtual circuit switching (also known as connection oriented). Some connectionless protocols are Ethernet, IP, and UDP; connection oriented packet-switching protocols include X.25, Frame relay, Asynchronous Transfer Mode (ATM), Multiprotocol Label Switching (MPLS), and TCP.
In connection oriented networks, each packet is labeled with a connection ID rather than an address. Address information is only transferred to each node during a connection set-up phase, when an entry is added to each switching table in the network nodes.
In connectionless networks, each packet is labeled with a destination address, and may also be labeled with the sequence number of the packet. This precludes the need for a dedicated path to help the packet find its way to its destination. Each packet is dispatched and may go via different routes. At the destination, the original message/data is reassembled in the correct order, based on the packet sequence number. Thus a virtual connection, also known as a virtual circuit or byte stream is provided to the end-user by a transport layer protocol, although intermediate network nodes only provides a connectionless network layer service.
The service actually provided to the user by networks using packet switching nodes can be either be connectionless (based on datagram messages), or virtual circuit switching (also known as connection oriented). Some connectionless protocols are Ethernet, IP, and UDP; connection oriented packet-switching protocols include X.25, Frame relay, Asynchronous Transfer Mode (ATM), Multiprotocol Label Switching (MPLS), and TCP.
In connection oriented networks, each packet is labeled with a connection ID rather than an address. Address information is only transferred to each node during a connection set-up phase, when an entry is added to each switching table in the network nodes.
In connectionless networks, each packet is labeled with a destination address, and may also be labeled with the sequence number of the packet. This precludes the need for a dedicated path to help the packet find its way to its destination. Each packet is dispatched and may go via different routes. At the destination, the original message/data is reassembled in the correct order, based on the packet sequence number. Thus a virtual connection, also known as a virtual circuit or byte stream is provided to the end-user by a transport layer protocol, although intermediate network nodes only provides a connectionless network layer service.
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