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Unknown Destination
page -36 OmniSwitch Troubleshooting Guide September 2005
Unknown Destination
Known L2 Source, Unknown L2 Destination
The Catalina ASIC
Packet arrives at Catalina. CRC check done. If valid CRC it is put on XYBUS to Coronado
The Coronado ASIC
• The FIFO logic maintains queues of frames from both Xybus interfaces and selects an incoming frame
for HRE processing. This FIFO is done on the on chip memory of the HRE.
• The parser logic selects fields from the frame to identify the protocol and find key values that are used
by the HRE for lookups (DA, SA)
• Coronado does a L2 SA pCAM lookup.
• Coronado determines this is a known source and retrieves Group ID.
• Coronado checks for special L2 DA (ARP,STP,IGMP,IPMS,Router)
• Coronado performs L2 DA pCAM lookup based on Group ID.
• Because the L2 DA is unknown on that NI, the lookup fails.
• Coronado sets the QID to the flood queue, and the PDI to the unknown_DA and ReQId is set to Soft-
ware queue for unknown_DA. 802.1Q header is added.
• Enqueue the data to the final QID. In this case the QID is 511. The QID determines the destination
port, priority and bandwidth.
• Coronado’s queue manager dequeues the frame based upon destination and priority. The frame is
output from the Coronado into the Nantucket switching fabric via the FBUS.
• Note the Queue Manager will alternately dequeue the Multicast and Unicast Queues.
The Nantucket ASIC
• The Nantucket sends the packet to all egress Coronados, that have the bit set in the VLAN flood vector
for this Group ID.
• The Nantucket provides minimal buffering and delivers data to the Coronado for egress processing.