Arbitration for the backplane is accomplished in the INB Time Division Multiplexing (ITDM) logic. The arbitration is a three-level scheme that ensures that no one can get the backplane for more than one time slice at a time.
The ITDM RAM contains 256 4-bit locations. This RAM is used to hold slot numbers of modules participating in INB backplane arbitration. The arbitration engine accesses this RAM once every time slice to get a slot number. That slot number will be granted access on the next time slice if it is requesting. The arbitration engine is always one time slice ahead, meaning that the value read from the RAM is for the next time slice, not the current time slice.
LANVIEW LEDs
The 9H423-28 module uses LANVIEW – the Cabletron Systems built-in visual diagnostic and status monitoring system. With LANVIEW LEDs, you can quickly identify, at a glance, system status as well as the device, port, and physical layer status. Two LEDs indicate the transmission and reception of data from the INB SmartSwitch 9000 backplane connection. Each of the 12 Ethernet front panel ports features two LEDs per port to indicate the port’s Administrative status (enabled/ disabled), LINK status (Link/Nolink), and Data Activity (receiving and transmitting data).
