Method and device for Hash lookup table

Abstract

The invention discloses a method and a device for a Hash lookup table. When storing a table, the method comprises the following steps of: planning a main table storage space which is divided into a plurality of address spaces; establishing a plurality of Hash functions and performing Hash calculation on a keyword of a piece of information to be stored by using the plurality of Hash functions to obtain a plurality of index values; and comparing the empty/full degrees of the address spaces corresponding to the plurality of index values and storing the information to be stored in the address space with the least stored information. When looking up the table, the method comprises the following steps of: using the plurality of different established Hash functions to perform Hash calculation on the keyword to be looked up so as to obtain a plurality of index values and performing match search on the keyword of a table entry of an address space position corresponding to the plurality of index values and the key word to be looked up. The method and the device for the Hash lookup table can save storage resource for the Hash table and improve the efficiency of Hash lookup.

Description

technical field [0001] The invention relates to the field of network communication, in particular to the problem of hardware implementation of a hash lookup table in network communication. More specifically, it relates to a method and device for a hash lookup table. Background technique [0002] In the field of network communication, lookup tables are essential, such as looking up MAC tables, ARP tables, MPLS label tables, etc., and hash lookup tables are a widely used method. A certain corresponding relationship f is established between its keywords, so that each keyword corresponds to a unique storage address in the hash table. The determined corresponding relationship f is the corresponding hash function. When the table is looked up each time, the storage table item is obtained through the hash function, and the relevant information bit of the table item is extracted, matched with the searched keyword, and the search result is returned according to the matching situation...

AI Technical Summary

Problems solved by technology

[0011] The Chinese patent application with the patent number CN200710049572 has the following deficiencies: one, the application of the invention adopts a master-slave parallel multi-core processor, and the complexity of the application of the multi-core processor has caused limitations in use; two, the invention uses multiple Memory management, that is, multiple hash storage tables, information interaction between these storage tables, etc. The invention does not explain

3. The invention does not provide the hardware implementation

[0012] The U.S. patent application with the patent number US20080034115 has the following deficiencies: the invention implements the hash table lookup in hardware, and proposes that information is stored in a CAM (ContentAddressable Memory) when the hash conflicts, and the CAM and the hash The method of looking up tables at the same time, the hardware implementation of this invention requires an external CAM, and a CAM addressing interface needs to be added, and when the conflict is severe, the information is concentrated in the CAM, resulting in a waste of storage space resources for the hash table, which cannot reflect the relationship between efficiency and resources fairness

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