Network Device Active Standby Switching via Control Apparatus
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Solution Overview
Problem
Existing network devices with active/standby forwarding boards require physical switching of I/O buses during switchover, leading to traffic interruption and increased downtime due to the need for physical connection changes and initialization processes.
Innovation Solution
The network device employs a control apparatus that manages packet flows between forwarding boards and an interface board without requiring physical switching of I/O buses, using independent PCI-E buses to maintain continuous operation by duplicating data packets and selectively connecting them to the network interface chip based on the active/standby state of the boards, thereby reducing traffic interruption to near-zero duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical switching of I/O buses is performed during active/standby forwarding board switchover, then the forwarding board can be switched between active and standby states, but traffic interruption occurs and downtime increases
Solution Approach 1:
The standby forwarding board pre-loads configuration data and maintains readiness state in advance, so when switchover is needed, it can immediately take over without waiting for initialization. This preliminary preparation eliminates the time-consuming configuration loading step that previously caused traffic interruption.
Solution Approach 2:
A switch fabric acts as an intermediary between the interface board and forwarding boards, allowing seamless redirection of traffic from active to standby board without physical disconnection or reconfiguration. The switch fabric absorbs the switching action, preventing traffic interruption at the network interface level.
2Adaptability or versatility
If physical connection of I/O bus is disconnected and re-established during switchover, then the newly-promoted active forwarding board can be configured, but the switching process becomes complex and time-consuming
Solution Approach 1:
The patent replaces physical mechanical switching operations with logical/software-based switching through the switch fabric. Instead of physically disconnecting and reconnecting I/O bus cables, the system uses virtual switching and configuration data redirection, dramatically simplifying the switching process while maintaining full configurability of the active forwarding board.
3Reliability
If initialization process is performed on newly-promoted active forwarding board, then the board can be properly configured, but traffic interruption duration increases to seconds
Solution Approach 1:
Configuration data is pre-loaded into the standby forwarding board's memory during normal operation. When switchover occurs, the board already has the necessary configuration data ready, eliminating the need for time-consuming initialization and configuration processes during the actual switchover event.
Solution Approach 2:
The switch fabric maintains continuous packet forwarding capability throughout the switchover process by redirecting traffic at the fabric level. This ensures that the useful action of packet forwarding continues uninterrupted, even while the logical configuration state changes from active to standby board.
Data Source
Figure 1~2a
Figure 2b
Figure 3
AI summary
A network device may include a first forwarding board, a second forwarding board and an interface board. The interface board may include a control apparatus and a network interface chip. The control apparatus may form a first upstream packet flow which is sent to the first forwarding board via a first I/O bus and a second upstream packet flow which is sent to the second forwarding board via a second I/O bus using data packets received through the network interface chip from the exterior of the network device. The control apparatus may selectively connect one of a first downstream packet flow and a second downstream packet flow to the network interface chip through the network interface bus according to an active/standby state of the first forwarding board and the second forwarding board, wherein the first downstream packet flow is processed by the first forwarding board and received through the first I/O bus and the second downstream packet flow is processed by the second forwarding board and received through the second I/O bus.