Avaya Configuring SDLC Services Manual do Utilizador descarregar pdf (Página 22)

Configuring SDLC Services

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114053 Rev. A

SDLC supports point-to-point and multipoint topologies. In point-to-point

topologies, only one SDLC device connects to the SDLC port. In multipoint

topologies, several SDLC devices connect to the SDLC port via a modem-sharing

type device.

SDLC Features

You can conﬁgure most of the following features using the SDLC parameters

described in Chapter 4.

Link Station Roles

A link station is a logical connection between adjacent nodes, where one node is a

primary link station and the other, a secondary link station. Only one link station

on an SDLC line can be the primary station; all others must be secondary. SDLC

supports primary, secondary, and negotiable link stations.

In DLSw conﬁgurations, a Bay Networks router must be conﬁgured as either a

primary or secondary link station. When primary, the router communicates with

downstream PU 2.0 and PU 2.1 nodes; when secondary, with front-end processors

and similar communications controllers. A secondary router functions as a PU 2.0

device.

In APPN conﬁgurations (PU 2.1 devices only), a Bay Networks router supports

negotiable link stations, where the two link stations exchange XIDs to negotiate

which one will be primary and which secondary.

Primary SDLC Support

A Bay Networks router conﬁgured as a primary device on an SDLC link can

• Control the data link

• Issue commands

• Initiate error-recovery procedures

The primary link station addresses and sends command frames to any or all

secondary link stations on the network. Each frame carries the individual, group,

or broadcast address of the station or stations to which the frame is directed. A

secondary link station receives commands and responds to primary link station

polls.

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