Virtual Network Path Determination Using Flow Trace Packets
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Solution Overview
Problem
Current techniques for managing virtual networks in cloud data centers face challenges in determining physical network paths within virtualized environments, particularly in multi-path routing scenarios where multiple paths of equal cost exist, leading to inefficiencies in packet flow allocation and latency measurement.
Innovation Solution
A distributed virtual network controller system that uses flow trace packets with incrementally increasing TTL values to determine physical network paths by generating and forwarding flow trace packets through the network, receiving corresponding time-exceeded messages to identify next hops, and aggregating these messages to determine the physical path taken by packet flows, ensuring accurate path matching and latency calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional trace route utilities are used in virtualized networks, then basic path discovery is possible, but path accuracy deteriorates in multi-path routing scenarios where multiple paths of equal cost exist
Solution Approach 1:
The patent introduces flow trace packets as an intermediary mechanism that carries flow identification information through the network. These packets act as mediators between the virtual network controller and physical network elements, enabling accurate path determination by matching the trace packet's flow ID with the actual packet flow's characteristics, thus resolving the ambiguity in multi-path scenarios
Solution Approach 2:
The patent changes the parameters used for path determination by incorporating flow identification fields and TTL (time-to-live) values into trace packets. By modifying these parameters and having network elements decrement TTL and return time-exceeded messages, the system achieves precise path measurement even in complex multi-path routing environments where conventional utilities fail
2Measurement precision
If flow trace packets with incrementally increasing TTL values are used, then path determination accuracy is improved, but network bandwidth consumption increases due to multiple packet transmissions
Solution Approach 1:
The patent applies partial action by sending flow trace packets with incrementally increasing TTL values only when needed for accurate path determination. Instead of continuously transmitting packets, the system uses selective TTL incrementation to probe the network path, achieving necessary measurement precision while minimizing unnecessary bandwidth consumption
Solution Approach 2:
The patent implements feedback mechanisms where network elements return time-exceeded messages to the virtual network controller when they receive flow trace packets with TTL=0. This feedback loop allows the controller to accurately determine path length and routing without requiring continuous packet transmission, thus reducing bandwidth usage while maintaining measurement accuracy
Data Source
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AI summary
In general, techniques are described for configuring and managing virtual networks. For example, a distributed virtual network controller is described that configures and manages an overlay network within a physical network formed by plurality of switches. A plurality of servers are interconnected by the switch fabric, each of the servers comprising an operating environment executing one or more virtual machines in communication via the overlay networks. The servers comprises a set of virtual switches that extends the overlay network as a virtual network to the operating environment of the virtual machines. The controller may instruct the servers and the virtual switches to perform various operations, such as determining a physical network path taken by packets of a network packet flow, determining latency through the network, re-routing traffic in the virtual network due to network events, replicating traffic for multicasting, providing multi-tenant services to support multiple virtual networks, monitoring and logging traffic characteristics within the virtual networks and other operations.