Ethernet Ring Protection Node Redundancy via Segmented Line Cards
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Solution Overview
Problem
Existing data-link-layer ring protection protocols, such as Ethernet Ring Protection (ERP), face challenges in maintaining connectivity when a node fails, as both ring ports going down disrupt communication within the ring and with external nodes, leading to loss of redundancy and increased risk of loops.
Innovation Solution
Implementing redundant state machines on separate line cards at each ring node, synchronized as a common logical state machine, to ensure continued connectivity and prevent loops by dynamically managing ring protection links and assigning roles to state machines for failure response and recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a node fails completely with both ring ports going down, then the failed node cannot communicate with other nodes in the ring, but the ring loses two links and nodes outside the ring connected to the failed node can no longer communicate with the ring
Solution Approach 1:
The patent segments the node's ring port functionality by implementing separate state machines on different line cards. Each line card maintains its own ring port and state machine independently, so that a failure of one line card does not necessarily take down the entire node's ring connectivity. This segmentation allows the node to maintain partial ring connectivity even when one line card fails.
Solution Approach 2:
The patent changes the operational state parameters of the ring ports dynamically. When a line card fails, the system detects the failure and changes the state of the remaining operational ring port from a blocked state to an active state, allowing traffic to flow through the alternative path. This parameter change enables the node to adapt its connectivity state based on failure conditions.
2Object-affected harmful factors
If ERP blocks a link between a designated pair of nodes to prevent loops, then all nodes in the ring can still communicate by passing information along remaining backbone links, but when a failure occurs elsewhere, the blocked link must be unblocked and a new blocked link created
Solution Approach 1:
The patent implements preliminary actions by pre-configuring multiple state machines on separate line cards before any failure occurs. Each state machine is prepared to take over ring protection functions if its counterpart fails. This preliminary setup eliminates the need for time-consuming recovery actions, as the system is already prepared with redundant state machines that can immediately assume control upon failure detection.
Solution Approach 2:
The patent implements feedback mechanisms where state machines continuously monitor the operational status of their counterparts and the ring links. When a failure is detected, the feedback triggers automatic state transitions in the remaining operational state machine, which adjusts its behavior to maintain ring protection. This closed-loop feedback system enables rapid response to failures without manual intervention.
3Adaptability or versatility
If additional ports connect a node participating in the ring to nodes outside the ring, then the node provides external connectivity, but when the node fails completely, nodes outside the ring connected through additional ports can no longer communicate with the ring
Solution Approach 1:
The patent segments the connectivity functions by separating ring port operations on different line cards. Each line card with additional ports maintains independent state machine control for its ring port. This segmentation ensures that additional ports on one line card do not become obsolete when another line card fails, as the remaining line card's ring port can still provide external connectivity access to the ring.
Solution Approach 2:
The patent creates a copy of the state machine functionality on separate line cards. Each line card has its own state machine that replicates the ring protection logic. This copying ensures that if one line card fails, the copied state machine on the other line card can take over and maintain external connectivity, preventing the loss of access for nodes outside the ring.
Data Source
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AI summary
Systems and methods are disclosed for providing redundancy in a network node implementing a ring protection protocol. Each of the two ring ports connecting the node to other nodes in a ring supporting the protocol may be maintained by a separate line card. Should one line card fail, traffic passing through the node may be redirected through the remaining ring port under the control of the surviving state machine. The two state machines may be coordinated over the backplane of the node to maintain a common state, making them transparent to other nodes. Additionally, the backplane link between the state machines may be monitored for failures that may be addressed with messages used to respond to general ring failures and by assigning one state machine to block a ring port upon recovery to prevent a loop within the ring until the ring protection link can be blocked.