X.25/QLLC

The ITU standard used for communication over a global packet-switching network that uses the qualified logical link control (QLLC) protocol is known as X.25. In a mainframe system, an X.25 line goes into an FEP, a communications controller, or an integrated X.25 adapter. With an AS/400, an X.25 line goes directly into the AS/400.

An X.25 connection is slower than 802.2-type connections and is comparable to an SDLC connection. This makes X.25 suitable for branch-type deployment strategies. These connections tend to be more common at European sites than at North American installations. Common line types and connection speeds are listed in Table 4.2.

SNA Server supports X.25 connections using the link support included with SNA Server, or through an X.25 link service available through various third-party vendors. Not all supported X.25 adapters support all link speeds listed in Table 4.2.