Stream Control Transmission Protocol (SCTP) is a connection-oriented transport layer protocol that supports reliable, message-oriented communication using multiple independent streams between two endpoints.
- It combines TCP's reliability and congestion control with UDP's message-oriented communication.
- Ideal for applications like telephony over the Internet and signaling in mobile networks.
Application
- Telephony Communication: VoIP signaling and telecom networks.
- Mobile Networks: Transports SS7 messages for 3G/4G/5G via M3UA, M2UA, SUA.
- Roaming & RAN Security: LTE/5G core network signaling and roaming infrastructure.
- Reliable Transport: Suitable for applications needing high reliability and low delay.
SCTP Packet Structure
An SCTP packet consists of a Common Header followed by one or more Chunks. The Header is common but the Payload has variable chunks. The Common SCTP header is 12 bytes long and made up of the 4 parts:
- Port Number (Source): shows the sending port
- Port Number (Destination): shows the receiving port
- Verification tag: a 32 bit random value which differentiate the packets from the previous connection
- Checksum: a CRC32 algorithm for detection of error.
Multihoming
Allows a host to connect through multiple IP addresses simultaneously. If the primary path fails, data automatically switches to an alternate path, ensuring continuous communication.
- Each path’s Round Trip Time (RTT) is monitored for reliability.
- This configuration increases network reliability and fault tolerance.
- Enables traffic to be distributed across multiple connections maximizing throughput.
- Ensures continuous operations during infrastructure disruptions.
Security
Provides certain security features related to transport such as resistance against blind DOS attack (Denial of Service), masquerades and monopolization of any type of service during operation.
- SIGTRAN (Signaling Transport) protocols does not define any type of new security mechanism.
- Current available security protocols provide necessary steps for securing the transmission of SS7 message over IP networks
Advantages
- Full duplex (send & receive simultaneously).
- Independent, ordered delivery per stream.
- Supports multiple IP paths (multihoming).
- Provides fault tolerance and congestion control.
- Message-oriented, unlike TCP’s byte-oriented approach.
