IBM 8260 manual Fddi Segments on the Backplane, SET Module slot.sublsot Network FDDIn

∙

∙

∙

∙

Data B transmit

Clock receive

Data A receive

Data B receive

The reasons for two signals for each of the transmit and receive signals is given in 8.2, ª8260 Backplane Signalling for TR Segmentsº on page 134.

Note that regardless of the number of token-ring modules used in a segment, you always have the ability to set up 10 separate token-ring segments on the ShuntBus.

The same pins that are used for token-ring segments on the ShuntBus are designed to be used for FDDI segments as well. Therefore, if you have a mixture of token-ring and FDDI segments on the ShuntBus, the maximum number of token-ring segments would be lower, depending on the number of FDDI segments. However, this is a theoretical limitation for the time being, as currently IBM is not offering any 8260 FDDI modules.

2.4 FDDI Segments on the Backplane

The 8260 allows you to set up a maximum of 4 FDDI segments on the Enhanced TriChannel using the 8250 modules. Also, it is possible to set up a maximum of 4 FDDI segments on the ShuntBus, using the 8260 FDDI modules. However, as there are no 8260 FDDI modules available yet, if you are planning to have FDDI segments on the 8260, you must use the 8250 FDDI modules to set up FDDI segments on the Enhanced TriChannel only.

Each FDDI module which is assigned to one of the four FDDI networks on the Enhanced TriChannel uses one of the resources called FDDI path. There are 8 FDDI paths on the Enhanced TriChannel and are referred to as fddi_path_8250_1 through fddi_path_8250_8. Each FDDI path utilizes 6 pins of the Enhanced TriChannel. These pins are as follows:

∙

∙

∙

∙

∙

∙

Data-in

Symbol parity-in

Clock-in

Data-out

Symbol parity-put

Clock-out

When you assign an FDDI module to one of the four FDDI networks on the Enhanced TriChannel (fddi_1 through fddi_4), using the following command:

SET MODULE {slot.sublsot} NETWORK {FDDI_n}

the 8260 will automatically allocate one of the available FDDI paths to this module. Note that you can neither choose the path used by a module, nor determine which path is used by a specific module. However, you can determine all the FDDI paths on the Enhanced TriChannel which are currently being used in your hub by using the following management module command:

SHOW BACKPLNE_PATHS FDDI

22 8260 Multiprotocol Intelligent Switching Hub