SNA Networking Protocols

System Network Architecture (SNA) by IBM is a suite of protocols mainly used with IBM mainframe and AS/400 computers.

APPC - Advanced Peer-to-Peer Communications provides peer to peer services at the transport and session layer. Part of the System Network Architecture (SNA) suite of protocols.
APPN - Advanced Peer-to-Peer Networking supports the computer connections at the network and transport layers. Part of the System Network Architecture (SNA) suite of protocols.

Other Protocols

DLC - Data Link Control. This protocol operates at the data link layer and is designed for communications between Hewlett-Packard network printers and IBM mainframe computers. This protocol is not routable.
OSI - Open Systems Interconnect. A suite of protocols developed by the International Standards Organization (ISO) which corresponds with the layers of the OSI model. These protocols provide a number of application protocols for various functions. The OSI protocol stack may be used to connect large systems. OSI is a routable transport protocol.

Mail Protocols

MIME - Multipurpose Internet Mail Extension is the protocol that defines the way files are attached to SMTP messages.
X.400 - International Telecommunication Union standard defines transfer protocols for sending mail between mail servers.

LDAP - Lightweight Directory Access Protocol is a standard for directory services with additional features that enhance its capabilities being added. LDAP may allow for consolidation of directory lists to be consolidated. An LDAP server provides the directory services and other LDAP functions.
X.500 - This is a recommendation outlining how an organization can share objects and names on a large network. It is hierarchical similar to DNS, defining domains consisting of organizations, divisions, departments, and workgroups. The domains provide information about the users and available resources on that domain, This X.500 system is like a directory. Its recommendation comes from the International Telegraph and Telephone Consultative Committee (CCITT).