Hybrid Memory for Search Operations

Abstract

Methods, systems, and computer readable storage medium embodiments for configuring a lookup table for a network device are disclosed. Aspects in these embodiments include generating a decision tree based upon bit representations of respective data entries from a plurality of data entries where one or more of the plurality of data entries are represented at respective nodes of the decision tree, storing a first bit pattern corresponding to a selected node from the decision tree in a content addressable memory (CAM) at a location associated with an index, and storing one or more second bit patterns at an address in a second memory. The one or more second hit patterns correspond to the one or more data entries represented at the selected node, and the address is associated with the index. Embodiments also include searching a lookup table in a network device.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This applications claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Appl. No. 61 / 610,720, filed Mar. 14, 2012, and U.S. Provisional Appl. No. 61 / 636,144, filed Apr. 20, 2012, which are hereby incorporated by reference in their entireties.BACKGROUND[0002]1. Field of the Invention[0003]Embodiments relate to searching the memory of processor-based devices and, in particular, to content addressable memories.[0004]2. Background Art[0005]Search efficiency is crucial for many computing functions including for packet processing in network devices, such as bridges, switches, routers, gateways, network proxies, network load balancing devices, and network security devices. One or more searches are performed for each packet at each hop along a network path, based upon the respective headers, to determine, for example, a next hop to which the packet is to be forwarded and / or to determine whether the packet can be forwarded based upon acce...

AI Technical Summary

Benefits of technology

The patent text discusses the problem of efficiently searching for content in network devices, such as routers and switches, as the size of search tables and power consumption associated with search operations can become large and scalability issues arise. The text describes various methods and systems for using content addressable memories (CAM) to compare search expressions to multiple stored entries simultaneously and determine the next hop for a packet. However, CAM and TCAM consume large amounts of power and can lead to increased power consumption as the size of the memory increases. To address these issues, the patent proposes methods and systems for more efficient use of CAM and other memory resources for lookup operations, including reducing the size of CAM and TCAM entries, optimizing decision trees for storing data entries, and compressing data entries. These methods and systems can improve search efficiency, reduce power consumption, and enhance the speed of packet forwarding in network devices.

Problems solved by technology

As computer networks grow, scalability issues arise with respect to search efficiency, search table size, and power consumption.

As search tables grow, their power consumption may also increase because some types of search tables, such as tables implemented in content addressable memory (CAM), consume large amounts of power.

However, although CAMs and TCAMs are fast, they consume large amounts of power relative to other types of memory.

The size of a CAM or TCAM directly affects the power consumption associated with that memory.

Images