IBM Advanced Peer-to-Peer Networking
| Company type | Technology/Networking Protocol |
|---|---|
| Industry | Computer networking |
| Founded | 1986 |
| Founder | IBM |
| Products | Systems Network Architecture (SNA) enhancement, High Performance Routing (HPR) |
IBM Advanced Peer-to-Peer Networking (APPN) represents an enhancement of the Systems Network Architecture (SNA), facilitating peer-level communication between both large and small computing systems over local and wide-area networks.
Objectives and Characteristics
The primary objectives of APPN included:
- Delivering optimized routing for SNA data flows
- Allowing session initiation without relying on a centralized host
- Minimizing the necessity for forecasting resource consumption
- Giving precedence to SNA traffic
- Accommodating both traditional and APPN-specific traffic
Notable characteristics comprise:
- Decentralized network management
- Real-time exchange of network topology information to simplify connection setup, network reconfiguration, and path determination
- On-demand definition of network resources
- Automated resource registration coupled with directory services for lookup
Development Background
Conceived circa 1986, APPN was created to extend IBM's Systems Network Architecture. Although designed to streamline networking, its implementation proved intricate, particularly during transition phases. Initially promoted as a potential "DECNET replacement," APPN outlived DECNET but has been mostly overtaken by the widespread adoption of the TCP/IP.
The technology advanced to incorporate High Performance Routing (HPR), a streamlined routing protocol introduced in the late 1990s within IBM’s enterprise networking solutions. Presently, HPR is predominantly utilized in IBM’s z/OS systems as a successor to traditional SNA infrastructures and continues operation within UDP tunnels through Enterprise Extender technology.
APPN governs communication between machines at the transport and network layers, distinguishing it from APPC, which manages interactions at higher network layers between software applications.
The designation "peer-to-peer" in APPN highlights its decentralized control architecture, which differs fundamentally from peer-to-peer file-sharing applications such as Bittorrent or emule.
Network Elements
An APPN environment may consist of up to five distinct node classifications:
| Network Node (NN) | functions as an APPN router |
| End Node (EN) | hosts applications |
| Low Entry Node (LEN) | original peer node enabling communication between two nodes through VTAM |
| Composite Network Node (CNN) | node operating under VTAM/NCP |
| Branch Network Node (BrNN) | serves as an EN to upstream NN while providing NN capabilities to downstream ENs and LENs |
Within VTAM, APPN nodes are identified as PU 2.1.
Supported Hardware and Software
APPN compatibility extends across a range of IBM and third-party intelligent devices and software platforms, including mainframe systems, AS/400, System/36, OS/2 via Communications Server, Cisco networking hardware, and Microsoft Host Integration Services (HIS) for Windows.