Redundant Switch Card Traffic Switchover with TCAM Rules
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The traditional method of enabling and disabling TCAM rules for traffic switchover in centralized switch architecture (CSA) network devices is slow and results in significant downtime due to the need to program multiple hardware tables for each front panel port, causing the device to halt network traffic processing during the switchover process.
Innovation Solution
Implementing a framework where TCAM rules are always enabled with additional match criteria based on a global object (such as a VLAN class ID or hardware signals) to redirect traffic to either the primary or secondary switch card, allowing for a rapid change in the global object to switch traffic to the secondary card upon failure, thereby minimizing downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional TCAM rule enabling/disabling method is used for traffic switchover, then traffic can be redirected to the active switch card, but the switchover process is slow and causes significant downtime
Solution Approach 1:
The patent applies preliminary action by pre-configuring TCAM rules for both primary and secondary switch cards before a failure occurs. Multiple TCAM rules are programmed in advance with different priority levels, so when a switchover is needed, the system can immediately activate the pre-configured rules without time-consuming programming operations. This eliminates the traditional sequential enable/disable process and achieves rapid failover.
Solution Approach 2:
The patent implements dynamics by making TCAM rule priorities dynamic and adjustable. The system can change the priority of pre-configured TCAM rules in real-time based on the operational status of switch cards. When the primary switch card fails, the system dynamically reconfigures the priority of existing TCAM rules to redirect traffic to the secondary card, avoiding the need to reprogram the entire TCAM table.
2Adaptability or versatility
If multiple TCAM rules are programmed for each front panel port, then traffic redirection capability is achieved, but the device must halt network traffic processing during switchover
Solution Approach 1:
The patent ensures continuity of useful action by maintaining multiple enabled TCAM rules simultaneously rather than sequentially enabling/disabling them. During normal operation, TCAM rules for the active switch card are enabled while rules for the standby card remain enabled but at lower priority. This allows the system to maintain full network traffic processing capability while having pre-prepared rules ready for immediate activation upon failure, eliminating service interruptions.
Solution Approach 2:
The system performs preliminary configuration of multiple TCAM rules with different priorities for each front panel port before any failure occurs. This pre-programming includes rules for both primary and secondary switch cards, so when switchover is needed, the system simply changes priority levels rather than programming new rules, maintaining continuous traffic processing without halting the device.
3Reliability
If TCAM rules are sequentially enabled and disabled during switchover, then traffic can be redirected, but the process is slow and causes downtime
Solution Approach 1:
The patent applies dynamics by implementing dynamic priority adjustment of pre-configured TCAM rules instead of sequential enable/disable operations. The system maintains all TCAM rules in an enabled state with dynamic priority levels that can be instantly adjusted. When switchover is required, the system dynamically changes the priority of existing rules rather than sequentially enabling and disabling them, achieving rapid failover in sub-100 milliseconds while maintaining reliable traffic redirection.
4Measurement precision
If the device halts network traffic processing during switchover to program hardware tables, then accurate traffic redirection is achieved, but significant downtime occurs
Solution Approach 1:
The patent applies preliminary action by pre-programming all necessary TCAM rules with correct destination information for both primary and secondary switch cards before any failure occurs. The hardware tables are pre-configured with accurate traffic redirection paths, so when a switchover is needed, the system only needs to adjust priority levels rather than reprogram the entire TCAM structure. This maintains precise traffic redirection accuracy while eliminating the need to halt network traffic processing.
Solution Approach 2:
The system maintains continuous network traffic processing by keeping all TCAM rules enabled and ready. The pre-configured hardware tables contain accurate redirection information for both active and standby switch cards, allowing the device to continuously process traffic without halting during switchover. The system achieves this by dynamically adjusting rule priorities rather than reprogramming hardware tables during failover.
Data Source
AI summary
Techniques for implementing optimized traffic switchover across the redundant (primary and secondary) switch cards of a network device are provided. In certain embodiments these techniques involve programming, for each front panel port of each the device's line cards, a first TCAM rule that includes a first match criterion matching network packets received on the front panel port, a second match criterion matching network packets received while a global object is set to a first value associated with the primary switch card, and a first action that causes matched network packets to be redirected to the primary switch card; and a second TCAM rule that includes the first match criterion, a third match criterion matching network packets received while the global object is set to a second value associated with the secondary switch card, and a second action that causes matched network packets to be redirected to the secondary switch card.