X.25 (1)
typically used in packet switched networks (PSNs) to provide connectivity across public data networks (PDNs)
Devices
- DTE - data terminal equipment (terminal, hosts)
- DCE - data circuit terminating equipment (modems, switches)
- PSE - packet switching exchange (switches)
- PAD - packet assembler / disassembler (used between DTE and DCE when DTE is too simple to implement X.25 functionality)