Diameter is a peer-to-peer protocol created as a next-generation version of RADIUS. Which port does it use?

Diameter is a peer-to-peer protocol created as a next-generation version of RADIUS. Which port does it use?

• A. 3868
• B. 1813
• C. 389
• D. 88

Answer: (A)

Diameter, as the newer version of RADIUS, standardizes on a distinct default port for its signaling. The base Diameter protocol listens on port 3868, with 3869 used for TLS-secured connections. This separation helps distinguish Diameter traffic from other services and reflects its push toward a more reliable, TCP/SCTP-based transport. Other commonly known ports belong to different technologies—1812 and 1813 are RADIUS ports (authentication and accounting), 389 is LDAP, and 88 is Kerberos—so they don’t apply to Diameter. Therefore, 3868 is the correct port.

Diameter, as the newer version of RADIUS, standardizes on a distinct default port for its signaling. The base Diameter protocol listens on port 3868, with 3869 used for TLS-secured connections. This separation helps distinguish Diameter traffic from other services and reflects its push toward a more reliable, TCP/SCTP-based transport. Other commonly known ports belong to different technologies—1812 and 1813 are RADIUS ports (authentication and accounting), 389 is LDAP, and 88 is Kerberos—so they don’t apply to Diameter. Therefore, 3868 is the correct port.