The Passport 4400 X.25 services provide connectivity between X.25 Data Terminal Equipment (DTE) devices within a Passport wide area network (WAN). The X.25 services also support X.25 calls between a DTE connected to a Passport 4400 unit and a DTE connected to a frame relay access device (FRAD), within a frame relay WAN.
A Passport 4400 unit functions as an X.25 data communication equipment (DCE) device, providing network services to users of external X.25 DTE devices connected to the unit's synchronous serial interfaces. These X.25 users can connect to X.25 devices connected to other Passport 4400 units, or to X.25 devices at FRADs that are accessible to the unit within a frame relay WAN. Here is an example application:
The Passport 4400 unit encapsulates X.25 data for transmission over a frame relay PANL or DLCI connection. The encapsulation method complies with Multiprotocol Encapsulation Implementation Agreement FRF3.1 (Frame Relay Forum, June 22, 1995) for single protocol X.25 encapsulation, to allow interworking with FRADs. The encapsulation procedure is described in ANSI T1.617a 1994 Annex G.
X.25 services traffic is passed transparently through Passport 6400 units.
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