Packet Forwarding via Multi-Bit Decision Diagrams

Solution Overview

Problem

Current tools for managing complex computer networks lack the ability to predict and efficiently store and access packet-forwarding rules, leading to inefficiencies in data traffic management and flow behavior analysis.

Innovation Solution

A novel data structure that uses multi-bit bit patterns to reduce the number of nodes required for implementing set operations between equivalence classes and packet sets, enabling more compact storage and faster access to packet-forwarding rules.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional binary decision trees are used to store packet-forwarding rules, then the rules can be stored, but significant overhead is incurred due to considering each bit as a separate variable with an associated decision node

Engineering Contradiction:

Improvestorage capabilityVSAvoiddata structure overhead

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple adjacent bits into a single multi-bit variable. Instead of creating separate decision nodes for each bit position, the invention combines groups of bits (e.g., 4 bits) into one variable that is evaluated as a unit. This merging reduces the total number of decision nodes from potentially hundreds (one per bit) to a manageable number (one per multi-bit group), directly resolving the overhead problem while maintaining complete storage capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent transitions from a one-bit-at-a-time decision approach to a multi-dimensional approach where multiple bit positions are collapsed into single variables representing larger units. By changing the dimensionality of the decision variables from individual bits to multi-bit groups, the data structure achieves more compact representation without losing the ability to distinguish between different packet-forwarding rule conditions.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If each bit of IP or MAC address is considered a variable with an associated decision node, then complete packet-forwarding rules can be represented, but the number of nodes increases significantly

Engineering Contradiction:

Improverule representation accuracyVSAvoidnumber of decision nodes

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent merges multiple adjacent bits into a single multi-bit variable. Instead of creating separate decision nodes for each bit position, the invention combines groups of bits (e.g., 4 bits) into one variable that is evaluated as a unit. This merging reduces the total number of decision nodes from potentially hundreds (one per bit) to a manageable number (one per multi-bit group), directly resolving the overhead problem while maintaining complete storage capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent creates multi-bit variables that serve multiple functions simultaneously. Each multi-bit variable represents multiple bit positions and can capture multiple patterns of interest. This multi-functionality allows a single decision node to perform what would otherwise require multiple separate nodes, reducing overall structure complexity while preserving rule representation accuracy.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Quantity of substance

If hypercubes, bit vectors, or binary decision trees are used to store large numbers of packet-forwarding rules, then storage is possible, but access speed and efficiency become problematic due to high dimensionality

Engineering Contradiction:

Improvenumber of rules storedVSAvoidaccess speed

Core Design Contradiction:

Quantity of substanceVSSpeed

Solution Approach 1:

The patent merges multiple adjacent bits into a single multi-bit variable. Instead of creating separate decision nodes for each bit position, the invention combines groups of bits (e.g., 4 bits) into one variable that is evaluated as a unit. This merging reduces the total number of decision nodes from potentially hundreds (one per bit) to a manageable number (one per multi-bit group), directly resolving the overhead problem while maintaining complete storage capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent segments the high-dimensional bit space into manageable multi-bit groups. By dividing the address space into segments of multiple bits and treating each segment as a discrete variable, the invention creates a hierarchical structure that is more efficient for traversal. This segmentation allows the system to handle large numbers of rules by organizing them into fewer, more manageable decision layers.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11184282B1Packet forwarding in a network device

Publication Date: 2021.11.23 VMWARE INC

AI summary

An example method of packet forwarding for a packet set in a network device includes: selecting a first bit pattern of multiple adjacent bits from a bit string that represents an input packet set; selecting a second bit pattern of multiple adjacent bits from a first node of a data structure that implements a prefix-compressed decision diagram representing a first class of packets; performing a comparison of the first bit pattern to the second bit pattern; generating an output packet set, which is a subset of the input packet set, in response to the first bit pattern matching the second bit pattern; and applying a network forwarding action to the output packet set, the network forwarding action associated with the prefix-compressed decision diagram and dictating packet forwarding behavior of the network device with respect to the output packet set.