Resource Time Sharing - 2.3 English

Ternary CAM Search LogiCORE IP Product Guide (PG318)

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2.3 English

The CAM Database is designed to run at a clock frequency of up to 600 MHz and process one Lookup Request every clock cycle. A search operation requires a number of RAM accesses. The RAM accesses can be performed in parallel using multiple RAM instances, sequentially by performing multiple accesses in the same RAM, or by a combination of both parallel and sequential access. For example if the RAM Frequency is 600 MHz and the Lookup rate is 300M Lookups per second, two accesses can then be performed using the same RAM.

The possible amount of time sharing of the RAM is calculated using integer division:


The TDM_FACTOR is rounded down to the nearest power of two and capped at 32. The following values are allowed: 1, 2, 4, 8, 16, and 32.

Table 1. Clock Configuration Examples
Ethernet Speed Lookup Rate [Mlps] Lookup Interface Frequency [MHz] RAM Clock Frequency [MHz] Clocking Mode TDM Factor
10G 15 15 15 SINGLE_CLOCK 1
10G 15 30 30 SINGLE_CLOCK 2
10G 15 30 480 DUAL_CLOCK 32
100G 150 150 150 SINGLE_CLOCK 1
100G 150 300 300 SINGLE_CLOCK 2
100G 150 300 600 DUAL_CLOCK 4
400G 600 600 600 SINGLE_CLOCK 1