Programmable SDN Loop Detection Using OFDP Packet Echoes
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Solution Overview
Problem
Network loops in SDN networks are difficult to detect and remediate due to their isolation to specific traffic types, leading to issues like broadcast storms that consume bandwidth and degrade network functionality.
Innovation Solution
An SDN controller with a loop detection subsystem that generates and authenticates OFDP packets to identify network loops, and upon detection, implements remedial actions such as disabling ports or sending notifications to prevent loop-related issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional loop detection methods are used, then network loops can be detected, but detection precision is insufficient because loops are isolated to specific traffic types and difficult to detect
Solution Approach 1:
The patent introduces an intermediary detection mechanism that uses a spanning tree protocol root bridge identifier embedded in data frames. This intermediary approach allows the system to detect loops indirectly by monitoring for duplicate root bridge identifiers, overcoming the limitation of traditional methods that struggle to detect loops isolated to specific traffic types. The intermediary mechanism transforms the detection problem from directly observing loop traffic to detecting the presence of duplicate identifiers that indicate loop conditions.
2Reliability
If network loops are not detected and remediated, then network functionality is maintained, but broadcast storms occur that consume bandwidth and degrade network functionality
Solution Approach 1:
The patent implements preliminary action by continuously monitoring for loop conditions using the spanning tree protocol root bridge identifier detection mechanism before broadcast storms can develop. The system proactively identifies potential loop conditions by detecting duplicate root bridge identifiers in data frames and triggers remediation actions in advance. This preliminary detection and response approach prevents the formation of broadcast storms, thereby maintaining network reliability and preventing bandwidth consumption issues before they occur.
3Reliability
If ports are disabled to eliminate network loops, then loop-related issues are prevented, but other connections may be disrupted
Solution Approach 1:
The patent applies local quality by implementing precise localization of loop conditions through the detection of duplicate spanning tree protocol root bridge identifiers. Instead of broadly disabling ports that might affect entire network segments, the system identifies the specific local area where loops exist by tracking which ports receive duplicate identifiers. This localized detection enables targeted remediation that affects only the specific ports involved in loop conditions, preserving the availability of other connections while still preventing loop-related issues.
Data Source
AI summary
A device may include a loop detection subsystem to place a network flow on a first switch to forward any received open flow discovery protocol (OFDP) packets to the software-defined network (SDN) controller. The device may cause the first switch to egress a query OFDP packet out of a first port of the first switch. The device may detect that the first port on the first switch is attached to a network loop based on the same query OFDP packet being ingressed by the first port of the first switch. The device may implement a remedial action in response to the detected network loop.