Fibre Channel Transport Interface Buffer Segmentation
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Solution Overview
Problem
Fibre Channel links face inefficiencies in data transport when oversubscribed over DWDM or SONET/SDH networks, leading to unused transport capacity and increased latency due to large ingress memory requirements and flow control latency.
Innovation Solution
Implementing a transport interface with a small ingress buffer for oversubscription and an egress buffer for flow control, allowing local generation and distribution of ready indications based on preconfigured bandwidth sharing weights, enabling statistical multiplexing without significant buffer memory increases or latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large ingress buffer is used to handle flow control credit grants, then Fibre Channel oversubscription capability is improved, but buffer memory requirements and cost increase significantly
Solution Approach 1:
The patent segments the buffer functionality by introducing a separate egress buffer dedicated to flow control operations, distinct from the ingress buffer. This segmentation allows the ingress buffer to be smaller since flow control credit tracking is handled by the specialized egress buffer, thereby reducing overall memory requirements while maintaining oversubscription capability
Solution Approach 2:
The patent introduces an intermediary egress buffer that mediates between the ingress buffer and the Fibre Channel ports. This intermediary structure handles flow control credit grants and ready indication generation, allowing the ingress buffer to operate with smaller capacity while still supporting oversubscription through the intermediary's buffer management
2Length of stationary object
If flow control ready indications are communicated over distant Fibre Channel links, then remote port connectivity is enabled, but latency in flow control operations increases
Solution Approach 1:
The patent implements preliminary action by locally generating ready indications at the ingress buffer based on preconfigured bandwidth sharing weights and current buffer status, rather than waiting for remote port feedback. This preliminary generation of flow control signals reduces the round-trip latency inherent in distant Fibre Channel link communications
3Reliability
If transport network capacity is allocated based on maximum Fibre Channel throughput, then bandwidth guarantees are provided, but transport capacity utilization efficiency decreases
Solution Approach 1:
The patent implements dynamic bandwidth allocation by allowing multiple Fibre Channel links to share transport network capacity based on preconfigured weights and actual traffic demand. The system dynamically adjusts ready indication distribution among ports according to their weights and current buffer status, enabling efficient statistical multiplexing while maintaining reliability through controlled flow control
Solution Approach 2:
The patent changes the parameter of bandwidth allocation from fixed maximum throughput guarantees to dynamic weighted sharing. By modifying how bandwidth is distributed (based on weights and actual usage rather than maximums), the system achieves both reliable service differentiation and improved overall capacity utilization through statistical multiplexing
Data Source
AI summary
Oversubscription of Fibre Channel links over a transport network is provided. A transport interface according to the present invention may maintain a small ingress buffer in addition to the normal egress buffer. The ingress buffer is primarily used for oversubscription and the egress buffer is primarily used for flow control. Ready indications to multiple local Fibre Channel ports may be locally generated when flow control conditions permit and may be distributed among the local Fibre Channel ports in response to preconfigured bandwidth sharing weights. Transport network efficiency is achieved by statistical multiplexing without significant increase in buffer memory requirements or introduction of latency into the flow control mechanism.