Filter
Top Products
OS6624/6648 Architecture
page -48 OmniSwitch Troubleshooting Guide September 2005
Address Look-up Methodology
Source and Destination Addresses are searched in parallel and then a sync process occurs to ensure both
are completed. The IXE2424 uses a fast method of organizing and searching the address records to meet
wire speed performance requirements. Record Entries (see Layer 2 Data Structures section below) contain
the addresses. A proprietary binary search algorithm is employed to look for these addresses; no hashing
algorithm is used. Records are organized into 1366 sections of 12 each (supporting a maximum of 16K
records) for L2. A similar organization exists for IP records (64K max records) and IPX (8K max entries).
Note that in Layer 2 only mode, all 40K addresses can be MAC addresses.
For the Hawk platform we will only use the ASIC in mode 4, which is Layer 3 switching with routing and
Layer 4 classification. Phase 1 will be L3 switching with L4 classification.
A binary search (on-chip) is performed among the Last Address (LA) of every section to find section
where the address should belong. A discriminated search is then performed with 10 bits to locate the
Record Entry where the address will fall if it is present. An external search for the record entry is then
performed. If the Record Entry matches with the address for which the search is performed, the rules and
protocol entries are also retrieved from external RAM.
L2 Data Structures
The layer 2 data structures for OS6600 are:
• 1-Record Entry
• Contains exact address used for match when searching tables
• MAC Address
• VLAN Tag ID (VID)
• 2-Rules Entry
• Contains information on which port the address resides on
• Device Number (IXE2424 number in cascaded systems)
• Port Number (which port this address resides on)
• Pointer to Protocol Specific Information
• Pointer to Destination Swap Information