IBM 8260 manual Backplane Architecture, LAN Segments on the Backplane

Chapter 2. Backplane Architecture

The 8260 backplane consists of the following two buses:

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Enhanced TriChannel

ShuntBus

These two buses are standard features of all the 8260 models and are installed on every 8260 shipped to the customers.

The following sections provide detailed information about the 8260 backplane and how the backplane buses operate.

2.1 LAN Segments on the Backplane

On each backplane bus (both Enhanced TriChannel and ShuntBus) there are 96 pins which are used for passing the network traffic between the media modules installed in the hub as well as the control signals between the media modules, fault-tolerant Controller module, and Distributed Management Module (DMM).

The control signals are used to carry clocking, voltage, status and other information pertinent to the proper operation of the hub and the installed modules.

On the Enhanced TriChannel, 54 pins are available to be used for passing network traffic. the rest of the pins are used for non-data traffic signals. These signals are used for passing control signals between the Controller module and the media modules as well as signals between the Management module and the media modules. More information about these non-data traffic signals are provided in 2.5.1, ªManagement Busesº on page 26.

On the Enhanced TriChannel, the pins used for passing the network traffic are not permanently allocated to a specific type of network. Instead a pin may be configured to be used for passing either token-ring, Ethernet or FDDI packets at any one time. This enables more efficient utilization of the backplane resources.

The following is the maximum number of permitted LAN segments when a single protocol is used on the Enhanced TriChannel:

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6 Ethernet segments or

7token-ring segments or

4FDDI segments

Note that you are allowed to have a mixture of token-ring, Ethernet and FDDI segments on the Enhanced TriChannel. In this case, the exact number of each network type which is allowed in a mixed protocol environment depends on the configuration of your hub. For detailed information about the permitted configurations in a mixed protocol environment please refer to 2.5, ªNetwork Allocations on the 8260 Backplaneº on page 23.

Figure 3 on page 14 provides an overview of the Enhanced TriChannel bus.

© Copyright IBM Corp. 1995 13