OpenFlow Switch Link Failure Detection and Traffic Redirection
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Solution Overview
Problem
Current OpenFlow Switch specifications face high latency and scalability issues in protection switching due to the need for centralized control in failure detection and traffic redirection, which also risks false positives from monitoring the secure channel itself.
Innovation Solution
Implementing Bidirectional Forwarding Detection (BFD) packets within the OpenFlow switch to detect link failures and redirect traffic to backup links, using virtual ports and MPLS-TP for packet processing and OAM signaling to manage failure detection and traffic rerouting locally within the switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If centralized control is used for failure detection and traffic redirection in OpenFlow networks, then control and management is simplified, but latency increases and scalability deteriorates
Solution Approach 1:
The patent segments the protection switching function into two parts: failure detection is performed centrally by the controller, while traffic redirection is executed locally by the switch using pre-configured backup paths. This segmentation allows the switch to immediately redirect traffic upon receiving a failure notification without waiting for centralized control decisions, thereby reducing latency while maintaining manageable control complexity.
Solution Approach 2:
The patent implements preliminary action by pre-configuring backup paths and redirection rules in the switch's flow table before failures occur. When a link failure is detected, the switch can immediately activate the pre-configured backup path without requiring real-time computation or control messages for path calculation, thus significantly reducing protection switching latency.
2Device complexity
If centralized control is used for failure detection and traffic redirection, then control is simplified, but scalability worsens
Solution Approach 1:
By segmenting the control architecture so that the controller handles high-level failure detection while switches autonomously execute traffic redirection using local flow tables, the system reduces the control burden on the centralized controller. This enables better scalability as multiple switches can independently handle failures without requiring centralized coordination for each redirection event.
Solution Approach 2:
The switch performs self-service by autonomously redirecting traffic to backup paths using pre-configured flow entries when link failures are detected. This self-service capability reduces the need for continuous centralized control intervention, improving network scalability as the number of switches increases.
3Device complexity
If secure channel monitoring is used for failure detection, then centralized control is maintained, but false positives increase
Solution Approach 1:
The patent extracts the failure detection function from secure channel monitoring and implements it through dedicated BFD packets sent over the actual data links. This separation allows failure detection to focus solely on link status without being confounded by secure channel issues, thereby improving failure detection accuracy and reducing false positives while maintaining the centralized control architecture.
Data Source
AI summary
Failure detection and traffic redirection are implemented in an OpenFlow switch. Link failure detection packets, such as Bidirectional Forwarding Detection (BFD) packets, are periodically sent out on links to peer OpenFlow switches, such as via the Multi-protocol Label Switching (MPLS) Transport Profile (MPLS-TP). Link failure detection packets are received from the peer OpenFlow switches on the links, and monitored. A link failure is detected if no incoming link failure detection packets are received on a link for a predetermined interval. In the event of a link failure, traffic is redirected from the failed link to a backup link by altering entries on a flow table of the OpenFlow switch.