Migrating X.25 over PSI to XOL

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Introduction
X.25 is the International Telecommunication Union-Telecommunication Standardization Sector (ITU-T)
protocol standard for WAN communication. X.25 defines how connections between user devices and
network devices are established and maintained in a packet switched data network.
With Ethernet evolving as the preferred network backbone for all environments, X.25 customers are
seeking solutions to run X.25 applications on Ethernet interfaces. Based on this feedback, HP offers
the X.25 over LLC2 (XOL) solution to run X.25 applications using Ethernet cards, instead of PSI
(Programmable Serial Interface) cards.
XOL enables easy migration of X.25 applications to LAN technology. XOL supports FDDI, token ring,
and Ethernet cards. High–speed Ethernet cards are preferred because of the high throughput.
Moreover, the total cost of ownership is lower when Ethernet cards are used, instead of PSI cards.
This document discusses the migration of X.25 over PSI to XOL using Ethernet cards. It also discusses
the benefits of migrating to XOL.
Definition of terms
Term Definition
API Application Programming Interface
CCITT International Telegraph and Telephone Consultative Committee
DCE Data Circuit terminating Equipment
DLPI Data Link Provider Interface
DSAP Destination Service Access Point
DTE Data Terminal Equipment
FDDI Fiber-Distributed Data Interface
HA High Availability
HDLC High level Data Link Control
IEEE Institute of Electrical and Electronics Engineers
ITU-T International Telecommunication Union-Telecommunication standardization Sector
LAN Local Area Network
LAPB Link Access Procedure Balanced
LLC Logical Link Control
LLC2 Logical Link Control type 2
MTU Maximum Transmission Unit
PLP Packet Layer Protocol
PSI Programmable Serial Interface
PSPDN Packet Switched Public Data Network
SAP Service Access Point
SAM System Administration Manager
SSAP Source Service Access Point