2.   Client Access

2.1         Client Connections

Users can access data in the Teradata Database through an application on both channel-attached and network-attached clients. Additionally, the node itself can act as a client. Teradata client software is installed on each client (channel-attached, network-attached, or node) and communicates with RDBMS software on the node. You may occasionally hear either type of client referred to by the legacy term of "host," though this term is not typically used in documentation or product literature.

2.2         Channel-Attached Client

Channel-attached clients are IBM-compatible mainframe systems supported by the Teradata Database. The following software components installed on the mainframe are responsible for communications between client applications and the Channel Driver on a Teradata node:

• Teradata Director Program (TDP) software to manage session traffic, installed on the channel-attached client.

• Call-Level Interface (CLI), a library of routines that are the lowest-level interface to Teradata.

Communication with the Teradata System

Communication from client applications on the mainframe goes through the mainframe channel, to the Host Channel Adapter on the node, to the Channel Driver software.

2.3         Network Attached Client

The Teradata Database supports network-attached clients connected to the node over a LAN. The following software components installed on the network-attached client are responsible for communication between client applications and the Teradata Gateway on a Teradata node:

• ODBC

• CLIv2

Communication with the Teradata System

Communication from applications on the network-attached client goes over the LAN, to the Ethernet card on the node, to the Teradata Gateway software.

2.4         Node

The node is considered a network-attached client. If you install application software on a node, it will be treated like an application on a network-attached client. In other words, communications from applications on the node go through the Teradata Gateway. An application on a node can be executed through:

• System Console that manages an SMP system.

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