Active/Active CVP Redundancy for Virtual Interfaces
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Solution Overview
Problem
Executing connectivity verification protocols over virtual interfaces in computer networks poses challenges, particularly in preventing false alarms and managing operability and accountability of line cards, due to the dynamic nature of virtual interfaces and the limitations of existing active/standby redundancy mechanisms.
Innovation Solution
Implementing an active/active redundancy mechanism where each connectivity verification protocol session operates on a group of two or more line cards, with one line card assuming a primary role and the others as backups, transmitting packets at a reduced rate to maintain the session and ensuring redundancy, thereby reducing latency and false positives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active/standby redundancy mechanism is used for CVP sessions on virtual interfaces, then failover capability is provided, but latency increases and false alarms occur due to the static nature of standby line cards
Solution Approach 1:
The patent transforms the static active/standby redundancy model into a dynamic active/active model where line cards can transition roles based on current operational status. The system continuously monitors line card health and dynamically reassigns primary/backup roles, eliminating the latency associated with cold standby cards while maintaining failover capability through real-time role switching.
Solution Approach 2:
The patent implements preliminary action by having backup line cards pre-synchronize state information and maintain readiness before failures occur. This pre-positioning of operational state allows for immediate takeover without waiting for failure detection and state synchronization, thereby reducing latency while preserving reliability.
2Adaptability or versatility
If CVP sessions are executed over virtual interfaces with dynamic line card assignment, then flexibility is improved, but false alarms increase due to inability to distinguish line card failures from routing changes
Solution Approach 1:
The patent implements feedback mechanisms where line cards report their operational status and receive acknowledgments from the control plane. This bidirectional feedback allows the system to distinguish between genuine line card failures and temporary routing changes, reducing false alarms while maintaining the flexibility of dynamic line card assignment for virtual interfaces.
Solution Approach 2:
The patent introduces an intermediary verification mechanism that acts as a mediator between the data plane (line cards) and control plane (routing protocols). This intermediary layer provides additional verification steps to confirm failures before triggering alarms, filtering out false positives caused by routing changes while preserving legitimate failure detection.
3Ease of operation
If single line card is assigned to CVP session, then accountability is simplified, but redundancy is lost when that line card fails
Solution Approach 1:
The patent segments the CVP session management into distinct functional components: primary line card responsible for packet transmission, backup line card responsible for state synchronization and takeover, and control plane for coordination. This segmentation maintains clear accountability for each function while providing redundancy through the specialized backup role, resolving the contradiction between simplified accountability and reliability.
4Loss of energy
If reduced packet transmission rate is used by backup line cards, then network traffic is reduced, but detection precision may be affected
Solution Approach 1:
The patent applies local quality by having different line cards transmit packets at different rates based on their specific roles. Primary line cards transmit at full negotiated rate for precise connectivity verification, while backup line cards transmit at reduced rates since their primary function is state synchronization rather than active verification. This differentiated approach maintains detection precision where needed while reducing overall network traffic.
Data Source
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AI summary
In one embodiment, a connectivity verification protocol (CVP) session for a particular virtual interface (VI) may operate on a particular group of two or more line cards (LCs) on a network device. The group of LCs may then transmit CVP session packets, at a reduced rate that is sufficient to maintain the CVP session based on a negotiated CVP full rate, onto the particular VI through ingress path processing on the network device. Ingress path processing, in particular, takes transmitted CVP session packets and egresses them onto an appropriate LC of the network device currently responsible for the VI egress. Also, in response to receiving CVP session packets for the VI on an LC of the network device currently responsible for the VI ingress, the receiving LC may forward the received CVP session packets to the particular corresponding group of LCs, which may then process the received CVP session packets.