Modified-Header Egress Processing with Separate Payload Storage
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Solution Overview
Problem
Network devices often drop or discard packets during egress processing, leading to incomplete mirroring of packets that are not transmitted, and existing systems cannot efficiently perform egress processing and mirroring before packet retrieval from memory.
Innovation Solution
A network device stores a packet's payload in memory and processes its header separately, allowing egress classification and mirroring decisions based on modified headers before enqueuing, ensuring mirroring only occurs for transmitted packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If packet mirroring is performed after egress processing, then packets can be mirrored based on final processing decisions, but packets that are dropped cannot be mirrored and resource utilization is reduced
Solution Approach 1:
The patent performs egress processing and congestion avoidance decisions before packet enqueuing in the egress queue. This preliminary action allows the system to determine whether to mirror packets based on final processing decisions before they are committed to the transmission queue, ensuring that only packets that will actually be transmitted are mirrored, thereby improving resource utilization while maintaining mirroring accuracy.
2Productivity
If packets are retrieved from packet memory for transmission, then packets can be processed and transmitted, but packets cannot be readily copied after egress processing because they are no longer stored in memory
Solution Approach 1:
The patent stores the packet payload in packet memory before egress processing is completed. This preliminary storage allows the packet to remain available in memory during the egress processing phase, enabling subsequent copying and mirroring operations before the packet is retrieved for transmission. This resolves the contradiction by maintaining packet availability in memory while enabling efficient processing and transmission.
3Reliability
If egress processing is performed before packet enqueuing, then mirroring decisions can be made based on modified headers, but packet processing order is constrained
Solution Approach 1:
The patent segments the packet processing into distinct phases: header modification, egress classification, congestion avoidance decision, and packet enqueuing. By separating these operations into discrete stages, the system can perform egress processing before enqueuing while maintaining clear processing sequence control. This segmentation allows modified headers to be used for accurate classification decisions without creating complex processing order constraints.
Data Source
AI summary
A network device includes a receive processor configured to store, in a packet memory, a payload of a packet received from a communication network. The network device also includes a packet processor configured to modify one or more fields of a header of the packet to generate a modified header, perform egress classification of the packet based on the modified header, and store the modified header in the packet memory. The network device further includes a transmit processor configured to transmit the packet in accordance with the egress classification. The transmit processor is configured to, in response to a decision that the packet is to be transmitted from the network device, generate a transmit packet from the payload retrieved from the packet memory and the modified header retrieved from the packet memory and cause the transmit packet to be transmitted to a destination in the communication network.