SCTP Programmer's Guide

Control Protocol (TCP) and the User Datagram Protocol (UDP). TCP supports
reliable and sequential packet delivery through error recovery and flow control
mechanisms. UDP is a simple message-based connectionless protocol compared
to TCP. SCTP is yet another transport layer protocol that application developers
can use to transmit data between endpoints.
• The socket layer provides the transport layer with an interface to interact with the
application layer. The socket layer contains a set of APIs, which facilitate the
transport layer to interface with the application layer.
• The application layer provides application programs with an interface to
communicate and transfer data across the network. All application layer protocols
use the sockets layer as their interface, to interact with the transport layer protocol.
Connection Setup in SCTP
This section discusses the connection setup between two endpoints in TCP and SCTP.
It also discusses how the connection setup in SCTP prevents the DoS attack.
Both TCP and SCTP initiate a new connection with a packet handshake. TCP uses a
three-way handshake to set up a new connection, whereas SCTP uses a four-way
handshake to set up a new connection.
Figure 1-2 illustrates the three-way handshake in TCP.
Figure 1-2 Three-Way Handshake in TCP
The following steps describe the three-way handshake in TCP:
SCTP Architecture 21