Lookup Units Power Reduction via Selective Enablement
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Solution Overview
Problem
Current network devices, such as routers and switches, face challenges in efficiently performing lookup operations due to high power consumption and heat dissipation issues associated with using ternary content-addressable memory (TCAM) chips, which are expensive and inefficient when handling large numbers of IP addresses.
Innovation Solution
The method involves distributing entries among multiple lookup units and selectively enabling only those units necessary for a lookup operation, using control logic to partition and repartition entries based on a Patricia tree representation, allowing each unit to be programmed with a subset of entries and only enabling units that may contain a matching entry, thereby reducing power consumption and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple TCAM chips are used to support large numbers of IP addresses, then the lookup operation can handle more addresses, but power consumption and heat dissipation increase significantly
Solution Approach 1:
The patent divides the TCAM chip into multiple smaller lookup units (e.g., four 8K-entry TCAM chips instead of one large chip). Each lookup unit handles a specific subset of IP address ranges, allowing the system to support large numbers of addresses while reducing the complexity and power consumption of individual lookup units. The control logic partitions the address space and enables only relevant lookup units for each packet forwarding decision.
Solution Approach 2:
The patent enables only the necessary subset of lookup units for each packet forwarding operation rather than activating all lookup units simultaneously. The control logic determines which lookup units are needed based on the packet's destination address and enables only those units, reducing overall power consumption while maintaining the capability to handle any possible IP address.
2Reliability
If all lookup units are enabled for every lookup operation, then complete coverage of all entries is ensured, but power consumption increases
Solution Approach 1:
The patent implements dynamic enabling of lookup units based on the specific lookup operation requirements. The control logic analyzes the packet forwarding decision and enables only the necessary lookup units for that particular operation. This dynamic approach ensures that all needed entries are searched while minimizing the number of active lookup units, thereby reducing power consumption without compromising lookup completeness.
Data Source
AI summary
Methods and apparatus are disclosed for distributing entries among lookup units and selectively enabling less than all of the lookup units when performing a lookup operation. Each of the lookup units is assigned a subset of the possible values of the entries and is programmed with the corresponding entries. In performing a lookup operation on a lookup word, only the lookup units possibly containing a matching entry are enabled which saves power and dissipates less heat. A lookup operation is then performed in the enabled lookup units to generate the lookup result. A lookup unit may correspond to an associative memory device, an associative memory bank, sets of entries within one or more associative memory devices or banks, a lookup control and a memory device, and/or any other lookup mechanism. In one implementation, the partitioning of elements is based on a Patricia tree representation of the possible entries.