Chapter 4 FortiOS Carrier : ­­­­Overview of FortiOS Carrier features : SCTP : Overview
  
Overview
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.
Table 36: 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.