Network Device Purge Queue for Bad Packet Segregation
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Solution Overview
Problem
Existing network devices face performance issues due to the handling of bad packets, which occupy buffer space and affect line rate performance, as they are typically queued with good packets, preventing parallel transmission and wasting output port bandwidth.
Innovation Solution
Implementing a purge queue at each output port to segregate and efficiently return bad packets to the free pool, utilizing spare bandwidth without impacting line rate performance, by adding an extra queue for bad packets and returning cells in parallel with good packet transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If bad packets are queued with good packets in the same output queue, then buffer space is utilized, but line rate performance deteriorates due to prevention of parallel transmission
Solution Approach 1:
The patent divides the output queue into two separate queues: a good packet queue and a bad packet queue (purge queue). This segmentation allows good packets and bad packets to be handled independently, enabling parallel transmission of good packets while efficiently returning bad packets to the free pool, thus resolving the contradiction between buffer utilization and line rate performance.
Solution Approach 2:
The patent extracts bad packets from the common output queue and places them in a separate purge queue. This extraction removes the harmful effect of bad packets blocking the transmission of good packets, allowing the system to maintain high line rate performance while still managing buffer space effectively.
2Device complexity
If bad packets are returned to free pool sequentially, then buffer management is simplified, but output port bandwidth is wasted
Solution Approach 1:
The patent enables continuous transmission of good packets while simultaneously returning bad packets to the free pool through the separate purge queue. This continuous parallel operation eliminates idle time on the output port, ensuring that bandwidth is not wasted while maintaining simple buffer management through dedicated queue structures.
3Productivity
If a separate purge queue is added for bad packets, then line rate performance is maintained, but device complexity increases
Solution Approach 1:
While adding a purge queue does increase structural elements, the segmentation creates a clean separation of concerns that simplifies the logic for handling bad packets. The increased structure is offset by the elimination of complex error handling logic that would be needed in a shared queue system, maintaining overall system simplicity.
Data Source
AI summary
A network device for processing packets includes at least one ingress module for performing switching functions on a packet, a memory management unit for storing the packet and at least one egress module for transmitting the packet to at least one port. The at least one egress module is configured to maintain multiple queues for the at least one port, including a purge queue, and to store the packet in the purge queue when an error condition is determined when the end of the packet is received by the at least one ingress module.