1ec8f24b7SThomas Gleixner# SPDX-License-Identifier: GPL-2.0-only 26a2e9b73SSam Ravnborg# 36a2e9b73SSam Ravnborg# CCITT X.25 Packet Layer 46a2e9b73SSam Ravnborg# 56a2e9b73SSam Ravnborg 66a2e9b73SSam Ravnborgconfig X25 770bd8f64SKees Cook tristate "CCITT X.25 Packet Layer" 8a7f7f624SMasahiro Yamada help 96a2e9b73SSam Ravnborg X.25 is a set of standardized network protocols, similar in scope to 106a2e9b73SSam Ravnborg frame relay; the one physical line from your box to the X.25 network 116a2e9b73SSam Ravnborg entry point can carry several logical point-to-point connections 126a2e9b73SSam Ravnborg (called "virtual circuits") to other computers connected to the X.25 136a2e9b73SSam Ravnborg network. Governments, banks, and other organizations tend to use it 146a2e9b73SSam Ravnborg to connect to each other or to form Wide Area Networks (WANs). Many 156a2e9b73SSam Ravnborg countries have public X.25 networks. X.25 consists of two 166a2e9b73SSam Ravnborg protocols: the higher level Packet Layer Protocol (PLP) (say Y here 176a2e9b73SSam Ravnborg if you want that) and the lower level data link layer protocol LAPB 186a2e9b73SSam Ravnborg (say Y to "LAPB Data Link Driver" below if you want that). 196a2e9b73SSam Ravnborg 20535094a0SAlexander A. Klimov You can read more about X.25 at <https://www.sangoma.com/tutorials/x25/> and 21706e282bSMichael Drüing <http://docwiki.cisco.com/wiki/X.25>. 226a2e9b73SSam Ravnborg Information about X.25 for Linux is contained in the files 23c4ea03fdSMauro Carvalho Chehab <file:Documentation/networking/x25.rst> and 24883780afSMauro Carvalho Chehab <file:Documentation/networking/x25-iface.rst>. 256a2e9b73SSam Ravnborg 266a2e9b73SSam Ravnborg One connects to an X.25 network either with a dedicated network card 276a2e9b73SSam Ravnborg using the X.21 protocol (not yet supported by Linux) or one can do 286a2e9b73SSam Ravnborg X.25 over a standard telephone line using an ordinary modem (say Y 296a2e9b73SSam Ravnborg to "X.25 async driver" below) or over Ethernet using an ordinary 306a2e9b73SSam Ravnborg Ethernet card and the LAPB over Ethernet (say Y to "LAPB Data Link 316a2e9b73SSam Ravnborg Driver" and "LAPB over Ethernet driver" below). 326a2e9b73SSam Ravnborg 336a2e9b73SSam Ravnborg To compile this driver as a module, choose M here: the module 346a2e9b73SSam Ravnborg will be called x25. If unsure, say N. 35