Cabletron Systems MMAC-Plus 9H421-12, User Manual, Page: 28 / 38

Operation
3-4
i960 Core
The i960 core provides the SNMP protocol stacks, to support industry standard
MIBs. Additionally, Cabletron enterprise extension MIBs are supported for each
media type. Advanced management services, such as telnet and network address
to MAC address mapping, are also provided by the i960 core.
The Host engine sends and receives packets via the CPU’s SmartSwitch ASIC
Interface. This allows the bridge to perform spanning tree protocol and other
bridging functions. The SMB Interfaces provide communication to the Host
Engine for management functions.
INB NIB
Each module that attaches to the Internal Network Bus (INB) has an INB Network
Interface Block (NIB). The INB NIB converts canonical frames to fixed length data
blocks for transmission onto the INB. For data blocks received from the INB, the
INB NIB reassembles the data blocks received from the INB back into canonical
frames for transmission to the SmartSwitch ASIC then from the SmartSwitch
ASIC to the front panel ports.
System Management Buses
There are two management channels within the SmartSwitch 9000 system: the
SMB-1 and the SMB-10. These buses provide side-band management and inter-
module management communication.
SMB-1 Bus
The SMB-1 is a 1 Mbps management bus located within the SmartSwitch 9000.
This bus is utilized by all diagnostic controllers in the system including
connectivity modules, power supply modules and the environmental module.
The SMB-1 transports inter-chassis information between system components,
such as power and environmental information, as well as diagnostic messages.
Periodic loop-back tests are performed by all modules which share this bus to
ensure the validity of SMB-1. In the event a failure is detected on SMB-1, the SMB-
10 may be used as an alternate communication channel.