Augmented Fibre Channel Frame Supplementary Header
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Solution Overview
Problem
The Fibre Channel (FC) protocol lacks support for inter-fabric communication, leading to increased latency and complexity in larger SANs, and there is a need for more economical implementation of high-performance, high port count switches.
Innovation Solution
An augmented FC frame format is introduced, which includes a supplementary header with a destination tag and egress port identifier, allowing for efficient inter-fabric communication and reduced latency by configuring switches to transport untranslated frames and using a core-edge topology with I-Ports and C-Ports for inter- and intra-switch communications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the FC protocol is used without augmentation, then the implementation is simpler and more economical, but inter-fabric communication is not supported and latency increases in larger SANs
Solution Approach 1:
The frame structure is segmented by adding a supplementary header field between the start-of-frame and frame header fields. This segmentation allows the frame to carry additional information about inter-fabric routing (destination fabric ID, egress port identifier) without altering the original FC frame structure, enabling inter-fabric communication while maintaining compatibility with existing FC infrastructure
Solution Approach 2:
The supplementary header acts as an intermediary layer that enables communication between different fabrics. It contains destination fabric identification information that allows switches to route frames across fabric boundaries without requiring full translation of the original FC frame, thus supporting inter-fabric communication while preserving the original protocol
2Adaptability or versatility
If a large number of translation operations are performed in larger SANs, then inter-fabric communication is enabled, but latency increases and complexity increases
Solution Approach 1:
The destination fabric ID and egress port identifier are pre-calculated and embedded in the supplementary header at the source switch. This preliminary action eliminates the need for intermediate switches to perform translation operations, as they can simply forward frames based on the pre-specified egress port identifier, thereby reducing latency
Solution Approach 2:
The routing information (destination fabric ID, egress port identifier) is extracted from the complex translation operation and placed in the supplementary header. This allows intermediate switches to perform simple forwarding based on the extracted information rather than performing full translation operations, reducing both latency and complexity
3Device complexity
If fabrics are made larger to reduce the number of switches, then customer preference for fewer large switches is satisfied, but reliability decreases and maintainability becomes more difficult
Solution Approach 1:
The invention maintains small fabric boundaries while enabling inter-fabric communication through the supplementary header. This segmentation approach allows the SAN to be divided into multiple small, reliable fabrics that can be independently maintained and managed, preserving the reliability advantages of small fabrics while achieving the customer preference for fewer switches through logical consolidation
4Adaptability or versatility
If the FC protocol is augmented with inter-fabric support, then inter-fabric communication is enabled, but the protocol complexity increases
Solution Approach 1:
The protocol is segmented by adding only the necessary supplementary header fields for inter-fabric communication rather than redesigning the entire FC protocol. This minimal augmentation approach enables inter-fabric functionality while keeping the overall protocol complexity low by preserving the original FC frame structure and processing logic
Solution Approach 2:
The supplementary header is designed to be universal, working with all FC frame types and existing FC infrastructure. This multi-functionality allows the same augmented protocol to handle both intra-fabric and inter-fabric communication, reducing the need for separate protocol mechanisms and thereby limiting the increase in protocol complexity
Data Source
AI summary
Accordingly, there is disclosed herein an augmented Fibre Channel (FC) frame format which may provide support for multiple fabric FC networks, and may improve the performance of modularly-constructed switches. In one embodiment, the augmented FC frame format is modulated on a carrier signal and the frame includes: a start-of-frame field; a supplementary header field that follows the start-of-frame field; a frame header field that follows the supplementary header field; a cyclic redundancy code (CRC) checksum field; and an end-of-frame field that follows the CRC checksum field. The supplementary header field may include a destination tag that identifies a target fabric to which the frame is directed. Alternatively, or in addition, the supplementary header field may include an egress port identifier that identifies a switch port through which the frame is to exit a switch. The supplementary header may also include flags to request special handling by the receiver.