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segments ethernet_4, ethernet_5 and ethernet_6 on the Enhanced TriChannel
and ethernet_7 and ethernet_8 on the ShuntBus.
•
Method 2:
This method also uses 14 pins on the backplane to set up an Ethernet
segment. In this method, each module attached to that Ethernet segment
will use digital collision detection identical to that used in method 1. This
means that the modules will send their slot-id in parallel over the backplane.
However, to allow the management module to collect statistics about these
modules, they send the slot-id and port-id in serial over a single pin on the
backplane.
This method is used by the 8260 modules when connected to ethernet_1,
ethernet_2, and ethernet_3 segments on the Enhanced TriChannel.
Method 2 is compatible with method 1. That is, modules using method 1 and
2 can be assigned to the same Ethernet LAN segment. Therefore, you may
set up ethernet_1, thru ethernet_3 to consist of a mixture of the 8250 and/or
8260 Ethernet modules.
•
Method 3:
This method uses only four pins on the backplane to set up an Ethernet
segment. In this method, each module will send its slot-id and port-id in
serial over a single pin on the backplane. This information allows the
management module to collect statistics about the modules and ports.
For collision detection, the modules using this method rely on an
analog
collision detection
as described in 2.2.2, “Analog Collision Detection” on
page 19.
This method is used by the 8260 modules when connected to ethernet_4,
ethernet_5, and ethernet_6 segments on the Enhanced TriChannel as well as
ethernet_7 and ethernet_8 segments on the ShuntBus.
This method is not compatible with methods 1 and 2. Therefore, ethernet_4
thru ethernet_8 segments can consist of 8260 Ethernet modules only.
Table 2 gives a breakdown of the pins which are used by 8250 and 8260 Ethernet
modules when using the above methods.
Table 2 (Page 1 of 2). Ethernet Pins on the 8260 Backplane
Description Method 1 Method 2 Method 3
Data enable signal Y Y Y
Data in NRZ format Y Y Y
Local collision Y Y N/A
Remote collision Y N N/A
Analog collision N/A N/A Y
Port ID bit 0 (lsb) Y N N/A
Port ID bit 1 Y N N/A
Port ID bit 2 Y N N/A
Port ID bit 3 (msb) Y N N/A
Slot ID bit 0 (lsb) Y Y N/A
Slot ID bit 1 Y Y N/A
Slot ID bit 2 Y Y N/A
Chapter 2. Backplane Architecture 17