162306a36Sopenharmony_ci# SPDX-License-Identifier: GPL-2.0-only 262306a36Sopenharmony_ci# 362306a36Sopenharmony_ci# CCITT X.25 Packet Layer 462306a36Sopenharmony_ci# 562306a36Sopenharmony_ci 662306a36Sopenharmony_ciconfig X25 762306a36Sopenharmony_ci tristate "CCITT X.25 Packet Layer" 862306a36Sopenharmony_ci help 962306a36Sopenharmony_ci X.25 is a set of standardized network protocols, similar in scope to 1062306a36Sopenharmony_ci frame relay; the one physical line from your box to the X.25 network 1162306a36Sopenharmony_ci entry point can carry several logical point-to-point connections 1262306a36Sopenharmony_ci (called "virtual circuits") to other computers connected to the X.25 1362306a36Sopenharmony_ci network. Governments, banks, and other organizations tend to use it 1462306a36Sopenharmony_ci to connect to each other or to form Wide Area Networks (WANs). Many 1562306a36Sopenharmony_ci countries have public X.25 networks. X.25 consists of two 1662306a36Sopenharmony_ci protocols: the higher level Packet Layer Protocol (PLP) (say Y here 1762306a36Sopenharmony_ci if you want that) and the lower level data link layer protocol LAPB 1862306a36Sopenharmony_ci (say Y to "LAPB Data Link Driver" below if you want that). 1962306a36Sopenharmony_ci 2062306a36Sopenharmony_ci You can read more about X.25 at <https://www.sangoma.com/tutorials/x25/> and 2162306a36Sopenharmony_ci <http://docwiki.cisco.com/wiki/X.25>. 2262306a36Sopenharmony_ci Information about X.25 for Linux is contained in the files 2362306a36Sopenharmony_ci <file:Documentation/networking/x25.rst> and 2462306a36Sopenharmony_ci <file:Documentation/networking/x25-iface.rst>. 2562306a36Sopenharmony_ci 2662306a36Sopenharmony_ci One connects to an X.25 network either with a dedicated network card 2762306a36Sopenharmony_ci using the X.21 protocol (not yet supported by Linux) or one can do 2862306a36Sopenharmony_ci X.25 over a standard telephone line using an ordinary modem (say Y 2962306a36Sopenharmony_ci to "X.25 async driver" below) or over Ethernet using an ordinary 3062306a36Sopenharmony_ci Ethernet card and the LAPB over Ethernet (say Y to "LAPB Data Link 3162306a36Sopenharmony_ci Driver" and "LAPB over Ethernet driver" below). 3262306a36Sopenharmony_ci 3362306a36Sopenharmony_ci To compile this driver as a module, choose M here: the module 3462306a36Sopenharmony_ci will be called x25. If unsure, say N. 35