Efficient TCAM implementation method based on SRAM

Abstract

The invention discloses an efficient TCAM (Ternary Content Addressable Memory) implementation method based on an SRAM (Static Random Access Memory). The method comprises the following steps: cutting an input table look-up key value into N sub-keys with W bit width according to a standard; judging whether the key value needs to be queried or not through a pre-table-look-up module; when the table pre-lookup result is that query is not needed, needing to insert a pipeline time delay module, simulating time delay generated by table lookup, and guaranteeing that the sequence of all table lookup results is consistent with that of input when the table lookup results are output; inquiring the SRAM table according to a table pre-lookup mode, performing logical AND on the found bitmap, and then mapping the final bitmap to a specific hit index. According to the method, the TCAM function can be realized by using the SRAM, a TCAMIP does not need to be additionally purchased, the size of the SRAM can be flexibly adjusted according to the table item specification, the limitation of the specific TCAM specification is avoided, and the chip project design progress can be effectively improved; and the overall area and the power consumption are more controllable.

Description

technical field [0001] The invention relates to the technical field of TCAM, in particular to an efficient SRAM-based TCAM implementation method. Background technique [0002] Content addressable memory (Content Addressable Memory), as a necessary function of network equipment, is usually implemented using TCAM IP. Generally, the memory accesses the stored content according to the address, but TCAM is just the opposite, and finds the address according to the content. The TCAM needs to ensure that all table entries are searched and matched at the same time, so as to ensure the forwarding performance requirements. The ACL function in the network device must use TCAM, so the built-in TCAM in the chip must exist, and some routing functions, such as LPM (Longest Prefix Match), may also use TCAM, but as a dedicated device, TCAM has access delay and power consumption, table items The specification flexibility and cell density cannot be compared with SRAM, and the TCAM IP of the c...

AI Technical Summary

Problems solved by technology

The ACL function in the network device must use TCAM, so the built-in TCAM in the chip must exist, and some routing functions, such as LPM (Longest Prefix Match), may also use TCAM, but as a dedicated device, TCAM has access delay and power consumption, table items The specification flexibility and cell density cannot be compared with SRAM. At present, the TCAM IP of the ASIC project needs to be purchased separately

Images