Emulex DCP_link manual Introduction, Chapter

7-2 Chapter 7

Introduction

Emulex X.25 software operates in a NetWare server or NetWare router/bridge PC environment and provides services for NetWare products and other applications (including independent developer applications) requiring wide area connectivity

Emulex X.25 uses the 1984 CCITT X.25 Recommendation, which defines the interaction between data terminal equipment (DTE) and data circuit- terminating equipment (DCE) of a packet-switching network.

In general the end user equipment (mainframe, pad, server) is DTE and the service provider (X.25) is DCE. In the illustration we see an example of a call established between two DTE connections.

IBM Compatible		X.25		Novell Server
DTE	DCE		DCE	DTE

DTE and DCE are both responsible for establishing, maintaining, and terminating the connection. The X.25 protocol primarily services between a DTE/DTE pair providing the DCE connection.

As described earlier the Emulex X.25 implements the 1984 CCITT X.25 recommendations, including the level 1 (physical), level 2 (frame), and level 3 (packet), along with several library modules. All three levels are generally configured as either DTE or all three as DCE though exceptions can occur. For example a DCE which accepts clock signals from a modem would have level 1 configured as DTE ( interface speed set to external).

Emulex X.25 interface runs in conjunction with NetWare MultiProtocol Router 3.0 and supports a wide variety of other proprietary software platforms.