Slides on transport protocols.
The transport layer (OSI layer 4) is the interface between the network and application (network API). The transport layer provides data transport service and some level of quality of service (QoS) to the application. While all transport protocols offer data transport services, they have varying levels of quality of service in terms of error detection and correction, packet ordering and packet delay. Simple transport protocols like UDP are often connectionless while connection-oriented transport protocols like TCP provide many quality of service properties.
Read More Download PDFOverview of SCTP (Stream Control Transmission Protocol), outlining the main features and capabilities of SCTP. SCTP is a transport protocol that overcomes many of the shortcomings of TCP, namely head-of-line blocking and stream-oriented transmission. SCTP supports multiple streams within a connection and preserves boundaries of application messages thus greatly simplifying communication. Additionally, SCTP supports multi-homing which increases availability in applications with high reliability demands. SCTP inherits much of the congestion, flow and error control mechanisms of TCP. SCTP has its roots in telecom carrier networks for use in transitional voice over IP scenarios. However, SCTP is generic so that it is applicable in many enterprise applications as well.
Read More Download PDFThis presentation outlines the core functions of TCP - Transmission Control Protocol. These comprise TCP Connection Control, TCP Flow Control, TCP Error Control, TCP Congestion Control, TCP Options and TCP Timers. TCP/IP is the Internet core protocol that provides reliable, connection-oriented and stream-based communication service. Most of Internet traffic is carried in TCP connections, so scalability and reliability are crucial for a stable network on a global scale.
Read More Download PDFUDP (User Datagram Protocol) is a simple extension of the Internet Protocol services. It basically provides simple packet transport service without any quality of service functions. Unlike TCP, UDP is connection-less and packet-based. Application PDUs (application packets) sent over a UDP socket are delivered to the receiving host application as is without fragmentation. UDP is mostly used by applications with simple request-response communication patterns like DNS, DHCP, RADIUS, RIP or RPC. Since UDP does provide any error recovery such as retransmission of lost packets, the application protocols have to take care of these situations.
Read More Download PDFTCP and UDP are the two transport protocols (OSI layer 4) that are predominantly used by applications in IP based networks. The properties of TCP and UDP are complementary in that TCP provides many quality of service features that UDP lacks. Therefore, TCP is mainly used in applications that require a certain level of reliable transport connection while UDP is used when reliability is of secondary importance but speed and simplicity are important. There are, however, alternatives to TCP and UDP. SCTP (Stream Control Transmission Protocol) was defined some time ago and was meant to eventually replace TCP. It provides the same features as TCP but fixes some of the shortcomings of TCP. Alternatives for UDP exist as well such as Reliable UDP and UDP redundancy.
Read More Download PDFA network socket is an interface for an application to connect to a host's network stack (part of the OS). Sockets provide an abstraction of the network. Applications use the transport services available on the socket interface for communication with a peer application. Transport protocol such as TCP, UDP or SCTP offer different levels of service. TCP for example provides reliable stream-oriented transport service while UDP more reflects the best-effort kind of service provided by the underlying IP protocol layer. Sockets provide only very basic data transport services without any higher level functions like parameter marshaling or serialization. These functions are often hidden in middleware platforms like distributed object technologies (CORBA, RMI, DCOM) or web service frameworks (WCF, JAX-WS). Multicast sockets make the IP multicast capability accessible to applications. Multicast sockets are often used for streaming services where multiple applications are recipients of the same data packets.
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