Cabletron Systems 9E428-36, User Manual

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3-1
Chapter 3
Operation
The 9E428-12 and the 9E429-12 modules are 13 port devices. Twenty four front
panel ST connectors support 12 10BASE-FL ports, each port being a separate
collision domain with the first port connecting to INB-B. The 9E428-36 and the
9E429-36 modules are 37 port devices. Seventy two front panel ST connectors
support 36 10BASE-FL ports, each port being a separate collision domain with the
first port connecting to INB-B.
As shown in Figure 3-1, Ethernet Network Interface Blocks (ENIBs) convert data
packets received from any of the 10BASE-FL ports into a canonical frame format
before forwarding to the SmartSwitch ASIC, while the Internal Network Bus
Network Interface Block (INB NIB) converts data packets received from the INB
into a canonical format before forwarding to the SmartSwitch ASIC.
All data packets destined for a front panel port, the INB, or the i960 are converted
into the canonical format before forwarding to the SmartSwitch ASIC. Network
Interface Blocks (NIBS) check for valid data packets entering the system. If an
errored data packet is found, the SmartSwitch ASIC flags the error and does not
forward the errored data packet to any outbound ports. Once in this common
format, the SmartSwitch ASIC decides from header information the port
destination of data packets. Data packets are then converted from the canonical
format to the proper format for the interface destination whether it is a front panel
port, or connection to the INB.