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Specific Packet Flows
OmniSwitch Troubleshooting Guide September 2005 page -35
Specific Packet Flows
Unknown L2 Source, Known 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 an unknown source due to failed lookup in L2 SA table.
• Since the SA is unknown, there is no pCAM entry, so the default Group ID (VLAN) is used
• If the port is secured then the frame is not forwarded
• The packet is requeued to NI SPARC, for software processing.
• Software creates an entry into the L2 SA table with packet’s mac address and Group ID
• Coronado checks for special L2 DA (ARP, STP, IGMP, IPMS, Router)
• Since the frame is known is present in the L2 DA table for that NI, the L2 entry provides the destina-
tion QID as well as the PDI (internal priority).
• Access the PDI and select internal priority.
• Enqueue the data to the final QID. 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 provides minimal buffering and delivers data to the Coronado for egress processing.
The Coronado ASIC
• The Coronado receives the packet via the FBUS.
• The Coronado then strips the 802.1q header that was added on ingress, if needed.
The Catalina ASIC
• Packet is then put on to the Xybus to be received by the Catalina.
• Catalina Egress will generate the CRC and regulate the packet framing including the interpacket gap.