Project Summary Performance of Network Redundancy in SCTP
Supervisor: Author: Institute: Prof. Dr. Stanislav Belenki Rashid Ali Department of Computer Science University West Trollhattän Sweden Creation Date: 01/03/11
Chapter: - 1
Transport layer protocols, Transmission Control Protocol (TCP) and User Datagram Protocol (UDP), the applications that need reliable and ordered delivery of the data use TCP and the applications that can tolerate certain degree of loss of data and also not regards the order of the bytes received use UDP. The UDP data transmission is speedier than the TCP because UDP work on connectionless terminology and TCP works on Connection-oriented. In TCP, the notion of a byte stream and a connection are equivalent. Every TCP connection has two endpoints, whereas UDP is connectionless and allows applications to send messages to one or many peers. There are also many applications that mark message boundaries over the TCP byte stream, because they need reliable message-oriented transport. In some cases, TCP either does not provide the exact functionality needed by the application or provides more functionality than is needed. In the first case, the application needs to do extra work to be able to use TCP, while in the latter; the extra functionality of TCP might be an overhead. For instance, many applications need reliable message delivery, but TCP is a byte stream oriented protocol. Message-oriented applications achieve their required functionality by delineating the TCP stream into messages. Additionally, TCP provides both strict ordering and reliability, but many applications may not need both. In this case, the applications will incur an overhead in using TCP. The Stream Control Transfer Protocol (SCTP) is a new transport protocol which provides a message oriented, reliable transport. It is similar to other transport protocols like TCP and UDP and is designed to hide the abstractions of the network layers from applications. SCTP is a reliable transport protocol operating on top of a potentially unreliable connectionless packet service such as IP. It offers acknowledged error-free non-duplicated transfer of datagram (messages). Detection of data corruption, loss of data and duplication of data is achieved by using checksums and sequence numbers. A selective retransmission mechanism is applied to correct loss or corruption of data. It was originally designed to be a general purpose transport protocol for message oriented applications, as is needed for the transportation of signaling data. SCTP is a transport layer protocol and its services are at the same layer as TCP and UDP. Similar to TCP, SCTP provides a reliable full-duplex connection, called an association. However, within an SCTP association, multi-streaming allows for independent delivery among streams, which reduces the risk of head-of-line blocking among application objects. SCTP supports multi-homing to provide redundancy at the path level, thus increasing association survivability in the case of a network path failure. Finally, SCTP's four-way handshake for association establishment makes it resistant to SYN attacks, and hence increases overall security. SCTP can take advantage of a multi-homed host using all the IP addresses the host owns. SCTP avoids a very simple attack that affects TCP, the so called SYN attack. Moreover, many features that are optional in TCP have been including in the basic specifications of SCTP, such as the Selective Acknowledgements, the ability to tell about the receipt of Duplicate Datagram or the support for Explicit Congestion Notification (ECN). SCTP Multi-homing-- An essential property of SCTP is its support of multi-homed nodes, i.e. nodes which can be reached under several IP addresses. If the SCTP nodes and the according IP network are configured in such a way that...