Packet Header Expansion and Collapse Using Bit Vectors for Lower Latency

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Solution Overview

Problem

Existing network switches face performance issues such as latency due to linear processing of protocol headers, which complicates hardware and requires overprovisioning of processing resources as network protocols evolve and fields within headers may not always be at fixed offsets.

Innovation Solution

A rewrite engine uses bit vectors to expand and collapse protocol headers into a generic format, maintaining a bit vector for each byte to mark valid and invalid fields, allowing flexible modifications through a set of generic commands stored in memory, independent of the protocol variation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If linear processing of each protocol layer is used, then protocol header modifications can be performed, but network latency increases and processing resources must be overprovisioned

Engineering Contradiction:

Improveheader modification capabilityVSAvoidnetwork latency

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The protocol header is segmented into multiple layers, with each layer processed independently and simultaneously. The rewrite engine divides the header processing task into discrete layer segments that can be handled in parallel, eliminating the sequential bottleneck and reducing overall processing latency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

All protocol layers are expanded to their maximum possible size in advance, with all potential fields included at fixed offsets. This preliminary expansion allows the rewrite engine to perform modifications without needing to dynamically adjust for optional fields, enabling faster parallel processing and eliminating the need for overprovisioned resources.

Inventive Principle:

Principle #10Preliminary action

2Speed

If protocol headers are processed with fixed field offsets, then processing speed improves, but hardware complexity increases to handle optional fields

Engineering Contradiction:

Improveprocessing speedVSAvoidhardware complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The rewrite engine is designed with a universal processing architecture that handles all protocol variations through a single set of fixed-offset fields. Each protocol layer is expanded to include all possible fields at predetermined offsets, allowing the same hardware logic to process any protocol variant without requiring complex conditional branching or dynamic offset calculation.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention changes the parameter of field offset from dynamic to fixed by expanding protocol headers to include all optional fields at predetermined positions. This parameter change simplifies the hardware processing logic while maintaining the ability to handle protocol variations through the use of bit vectors to track which fields are actually present.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If protocol headers are expanded to generic format with all possible fields, then flexibility for modifications improves, but memory requirements increase

Engineering Contradiction:

Improvemodification flexibilityVSAvoidmemory requirements

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

Bit vectors are introduced as an intermediary data structure to manage the expanded protocol headers. Each bit in the vector corresponds to a field in the header, indicating whether that field is present or optional. This intermediary allows the system to maintain the flexible generic format while efficiently tracking actual field presence, enabling memory optimization without sacrificing adaptability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12381963B2Method of using bit vectors to allow expansion and collapse of header layers within packets for enabling flexible modifications and an apparatus thereof

Publication Date: 2025.08.05 MARVELL ASIA PTE LTD

AI summary

Embodiments of the apparatus for modifying packet headers relate to a use of bit vectors to allow expansion and collapse of protocol headers within packets for enabling flexible modification. A rewrite engine expands each protocol header into a generic format and applies various commands to modify the generalized protocol header. The rewrite engine maintains a bit vector for the generalized protocol header with each bit in the bit vector representing a byte of the generalized protocol header. A bit marked as 0 in the bit vector corresponds to an invalid byte, while a bit marked as 1 in the bit vector corresponds to a valid byte. The rewrite engine uses the bit vector to remove all the invalid bytes after all commands have been operated on the generalized protocol header to thereby form a new protocol header.