IETF RFC 2960 PDF
Canonical URL: ; File formats: Plain Text PDF Discuss this RFC: Send questions or comments to [email protected] RFC Stream Control Discuss this RFC: Send questions or comments to [email protected] Abstract. This document obsoletes RFC and RFC The Stream Control Transmission Protocol (SCTP) is a computer networking communications protocol which operates at the transport layer and serves a role similar to the popular protocols TCP and UDP. It is standardized by IETF in RFC . RFC Stream Control Transmission Protocol (updated by RFC and.
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It differs from those protocols by providing multi-homing and redundant paths to increase resilience and reliability. It has since been widely ported.
RFC defines the protocol. RFC provides an introduction. SCTP places messages and control information into separate chunks data chunks and control chunkseach identified by a chunk header.
The protocol can fragment a message into a number of data chunks, but each data chunk contains data from only one user message.
One can characterize SCTP as message-oriented, meaning it transports a sequence of messages each being a group of bytesrather than transporting an unbroken stream of bytes as does TCP. As in UDP, in SCTP a sender sends a message in one operation, and that exact message is passed to the receiving application process in one operation. In contrast, TCP is a stream-oriented protocol, transporting streams of bytes reliably and in order.
However TCP does not allow the receiver to know how many times the sender application called on the TCP transport passing it groups of bytes to be sent out. At the sender, TCP simply appends more bytes to a queue of bytes waiting to go out over the network, rather than having to keep a queue of individual separate outbound messages which must be preserved as such.
The term multi-streaming refers to the capability of SCTP to transmit several independent streams of chunks in parallel, for example transmitting web page images together with the web page text. In essence, it involves bundling several connections into a single SCTP association, operating on messages or chunks rather than bytes. TCP preserves byte order in the stream by including a byte sequence number with iietf segment.
RFC – Stream Control Transmission Protocol (SCTP) Partial Reliability Extension
SCTP, on the other hand, assigns a sequence number or a message-id [note 1] to each message sent in a stream. This allows independent ordering of messages in different streams. However, message ordering is optional in SCTP; a receiving application may choose to process messages in the order of receipt instead of in the order of sending. The designers of SCTP originally intended ietc for the transport of telephony Signaling System 7 over Internet Protocol, with the goal of duplicating some of the reliability attributes of the SS7 signaling network in IP.
TCP has provided the primary means to transfer data reliably across the Internet. However, Ietg has imposed limitations on several applications. Adoption has been slowed by lack of awareness, lack of implementations particularly in Microsoft Windowslack of application support and lack of network support. Each SCTP end point needs to check reachability of the primary and redundant addresses of the remote end point using a heartbeat.
Each SCTP end point needs to ack the heartbeats it receives from the remote end point.
In Local multi homing and Remote single homing, if the remote primary address is not reachable, the SCTP association fails even if an alternate path is possible. Each chunk starts with a one byte type identifier, with 15 chunk types defined by RFCand at least 5 more defined by additional RFCs .
Eight flag bits, a two byte length field and the data compose the remainder of the chunk. If the chunk does not form a multiple of 4 bytes i. The two byte length field limits each chunk to a 65, byte length including the type, flags and length fields. Although encryption was not part of the original SCTP design, SCTP was designed with features for improved security, such ierf 4-way handshake compared to TCP 3-way handshake to protect against SYN flooding attacks, and large iegf for association verification and authenticity.
Reliability was also rfd key part of the security design of SCTP. Multihoming enables an association to stay open even when some routes and interfaces are down. SCTP is sometimes a good fingerprinting candidate. Some operating systems ship with SCTP support enabled, and, as it is not as well known as TCP or UDP, it is sometimes overlooked in firewall and intrusion detection configurations, thus often permitting probing traffic.
Stream Control Transmission Protocol