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Nantucket ASIC
page -18 OmniSwitch Troubleshooting Guide September 2005
Functional Description:
The Nantucket software resides on Chassis Management Module (CMM) and run on the UltraSPARC IIe
processor within the CMM. The Nantucket software communicates to the Nantucket ASIC via the PCI
Bridge and Bbus Bridges. The Nantucket Software has interfaces to the following:
• Primary CMM SDRAM, EEPROM via the UltraSparc IIe PCI Bridge
• Secondary CMM EEPROM via the UltraSparc IIe PCI Bridge
• 2 Primary Fabric Board Burst Bus Bridges via the UltraSparc IIe PCI Bridge
• 2 Secondary Fabric Board Burst Bus Bridges via the UltraSparc IIe PCI Bridge
• 8 Primary Fabric Board Nantucket ASICs via two Burst Bus Bridges
• 8 Secondary Fabric Board Nantucket ASICs via two Burst Bus Bridges
• Primary and Secondary Fabric Board Flash and Backplane EEPROM via the Burst Bus Bridge.
Data Flow
The following describes the data flow of unicast, Multicast and IP packets through the major modules of
the Nantucket ASIC:
• Receives serial input from Coronado at 500MHz
• Outputs 4 bit parallel data at 125MHz to the Data Port Input module
• Separates the 4 bit parallel input from the XyPhy input module into data and control streams.
• Send 192 bit data chunks to the Memory Manager module.
• Send chunk present, start of packet (SOP) and coupons to the Packet Chainer module.
The Packet Chainer Module performs:
• Processes incoming packet chunks from the Data Port Input module.
• Sends SOP, chain ID and packet type (unicast or multicast) to the Queue Manager module.
• For unicast and uP packets, decode the QID and pass the QID to the Queue Manager module upon
EOF.
• For multicast packets, decode the QID and pass to the Queue Manager module upon EOF.
The Queue Manager Module performs:
• Enqueues packets controlled by the Packet Chainer module, links the chain to the unicast queue or
copy the packet head pointer into multiple multicast fifos.
• Dequeues packets controlled by the Calendar Manager module from one of 512 unicast queues or one
of 16 multicast queues.
• Generates four paycheck messages for each physical port every 32.7 us denoting if measured queue
depth is above or below the pay threshold values.
• Generates a per physical port coupon message every 2us to the ingress Coronado denoting if measured
queue depth is above or below the coupon threshold value.