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Table of Contents

FortiOS Carrier

SCTP Concepts

SCTP is a connection-oriented transport protocol that overcomes some of the limitations of both TCP and UDP that prevent reliable transfer of data over IP-based networks (such as those used by telephony systems and carrier networks). The ‘Stream’ in SCTP refers to the sequence of user messages or packets that are considered at the same time to be individual objects and also treated as a whole by networked systems. SCTP is less vulnerable to congestion and flooding due to more advanced error handling and flood protection built into the protocol.

SCTP features as compared to TCP and UDP
Feature SCTP TCP UDP
State required at each endpoint yes yes no
Reliable data transfer yes yes no
Congestion control and avoidance yes yes no
Message boundary conservation yes no yes
Path MTU discovery and message fragmentation yes yes no
Message bundling yes yes no
Multi-homed hosts support yes no no
Multi-stream support yes no no
Unordered data delivery yes no yes
Security cookie against SYN flood attack yes no no
Built-in heartbeat (reachability check) yes no N/A

All of these features are built into the design of the Protocol, and the structure of SCTP packets and networks. The FortiGate unit interprets the traffic and provides the necessary support for maintenance and verification features, but the features are not FortiGate specific. These features are documented in greater detail below.

SCTP Concepts

SCTP is a connection-oriented transport protocol that overcomes some of the limitations of both TCP and UDP that prevent reliable transfer of data over IP-based networks (such as those used by telephony systems and carrier networks). The ‘Stream’ in SCTP refers to the sequence of user messages or packets that are considered at the same time to be individual objects and also treated as a whole by networked systems. SCTP is less vulnerable to congestion and flooding due to more advanced error handling and flood protection built into the protocol.

SCTP features as compared to TCP and UDP
Feature SCTP TCP UDP
State required at each endpoint yes yes no
Reliable data transfer yes yes no
Congestion control and avoidance yes yes no
Message boundary conservation yes no yes
Path MTU discovery and message fragmentation yes yes no
Message bundling yes yes no
Multi-homed hosts support yes no no
Multi-stream support yes no no
Unordered data delivery yes no yes
Security cookie against SYN flood attack yes no no
Built-in heartbeat (reachability check) yes no N/A

All of these features are built into the design of the Protocol, and the structure of SCTP packets and networks. The FortiGate unit interprets the traffic and provides the necessary support for maintenance and verification features, but the features are not FortiGate specific. These features are documented in greater detail below.