SCTP Administrator's Guide

1 Introduction
This chapter introduces the Stream Control Transmission Protocol (SCTP). It also
discusses the SCTP architecture and the utilities you can use to troubleshoot and monitor
and the SCTP product.
This chapter addresses the following topics:
• “SCTP Overview” (page 15)
• “SCTP Architecture” (page 15)
• “The ndd Command” (page 18)
• “The netstat Command” (page 23)
• “The nettl Command” (page 24)
• “The sctpd Application” (page 24)
• “Start and Stop Script” (page 25)
SCTP Overview
SCTP is a transport protocol that facilitates reliable transmission of data between two
endpoints of an association in an Internet Protocol (IP)-based network. In an IP stack, it
exists at a level equivalent to that of Transmission Control Protocol (TCP) and User
Datagram Protocol ( UDP).
SCTP supports multihoming, delivery of data in multiple streams, and preservation
of message boundaries. It also supports acknowledged, error-free, non-duplicated
transfer of data; fragmentation of data to conform to maximum transmission unit (MTU)
size; and optional bundling of user messages into an SCTP packet.
SCTP also includes mechanisms such as, checksums, sequence numbers, and selective
retransmission of data. In addition, it supports congestion control algorithms, SYN
flood protection , and error handling.
NOTE: In SCTP, the term “stream” refers to a sequence of user messages that are
delivered in sequence, with respect to other messages within the same stream. In TCP
"stream" refers to a sequence of bytes.
SCTP Architecture
This section discusses the SCTP architecture. It also discusses the various SCTP utilities
and describes how these utilities work.
SCTP is located between the SCTP user application (SCTP user for short) and a
connectionless packet network service, such as IP.
During association startup, SCTP enables each endpoint of an association to provide
the other endpoint with a list of multiple IP addresses in combination with SCTP ports
SCTP Overview 15