IBM Nways 8260 Manual page 40

The following is a brief description of the use of each of the pins in an Ethernet
segment on the 8260 backplanes:
18
8260 Multiprotocol Intelligent Switching Hub
Table 2 (Page 2 of 2). Ethernet Pins on the 8260 Backplane
Description
Slot ID bit 3
Slot ID bit 4 (msb)
Serial ID
Data enable signal :
When this signal is active, data on the backplane is valid and the modules
should receive and process the data on the Data in NRZ Format pin.
Data in NRZ format :
This signal is used to transmit data on the backplane in NRZ format.
Local collision :
This signal is used to indicate local collisions on the backplane. It is raised
when two or more modules on the same segment are transmitting data at
the same time. It is also raised if two or more ports on the same module
transmit simultaneously.
Remote Collision :
This signal is raised when a collision occurs in a remote hub. This signal is
only used by the 10Base-FB modules.
Port-ID:
Whenever an Ethernet module using method 1 transmits data on the
backplane, it must sent the port-id of the transmitting port on these pins.
The Management module will use the port-id and slot-id (see below) signals
to find out which port and module is sending the data on the Data in NRZ
Format pin; hence, it is able to collect and report per-port statistics.
Note: Since four pins are used to transmit the port ID in parallel, the
per-port statistics cannot be reported for all the ports of the 24-port modules.
On a 24-port module, you can collect statistics about the first 12 ports only.
Slot ID :
Whenever an Ethernet module is using method 1 or 2 to transmit data on the
backplane, it must send its slot-id on these five pins. This information is
used for two purposes:
1. Digital collision detection
2. Statistics collection
Serial-ID :
This pin is used to transmit the port-id and slot-id, over the backplane, in
serial format. Its purpose is to provide the Management module with a way
to collect per-port and per-module statistics for modules using method 2 and
3.
Analog Collision :
Method 1 Method 2
Y Y
Y Y
N Y
Method 3
N/A
N/A
Y