Ethernet Flow Control via Virtual Concatenation and Pause Frames
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current systems, such as the TRANSWITCH ETHERMAP-12, face limitations in multiplexing multiple SONET ports or virtual concatenated groups over a single Gigabit Ethernet link, particularly in supporting multiple OC-3 rings, and lack effective flow control mechanisms to manage congestion.
Innovation Solution
The method involves receiving multiple data streams over a single Ethernet link, associating buffers with each stream, monitoring buffer fullness, and transmitting PAUSE frames to control data flow, halting transmission to congested buffers until they decongest, using modified MAC frames and PAUSE control frames with programmable timers to manage congestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple SONET ports are multiplexed over a single Gigabit Ethernet link, then the device can support more OC-3 rings, but congestion management becomes difficult without proper flow control
Solution Approach 1:
The patent divides the single Ethernet link into multiple virtual channels, each carrying a separate SONET port or VCG. This segmentation allows independent flow control for each virtual channel while sharing the physical link, enabling support for multiple OC-3 rings with reliable congestion management through per-channel pause frame generation.
Solution Approach 2:
The patent introduces virtual concatenation groups (VCGs) as intermediary constructs that map multiple SONET ports onto a single Ethernet link. These VCGs act as mediators that enable multiplexing while maintaining individual flow control capabilities through associated FIFO buffers and pause frame mechanisms.
2Productivity
If a single FIFO is used for Gigabit mode, then the device supports a single OC-12 ring, but it cannot multiplex multiple SONET ports or VCGs
Solution Approach 1:
The patent segments the single FIFO resource into multiple virtual FIFOs, each associated with a specific SONET port or VCG. This virtual segmentation allows the single physical FIFO to handle multiple logical channels independently, enabling multiplication of supported ports while maintaining full utilization of the Gigabit Ethernet link.
Solution Approach 2:
The patent makes the single FIFO buffer serve multiple functions by implementing virtual concatenation groups that allow it to handle multiple SONET ports and VCGs simultaneously. This multi-functionality enables the buffer to support various multiplexing configurations while maintaining efficient link utilization.
3Reliability
If pause frames are generated for each FIFO, then flow control is effective, but the system complexity increases when supporting multiple OC-3 rings
Solution Approach 1:
The patent merges the flow control mechanisms of multiple virtual FIFOs into a unified pause frame generation system. When any virtual FIFO associated with a VCG becomes full, the system generates a single pause frame for the entire VCG, reducing the number of pause frames needed while maintaining effective flow control across all multiplexed ports.
Solution Approach 2:
The patent uses VCGs as intermediary structures that simplify complexity by grouping multiple SONET ports together. This grouping allows flow control to be managed at the VCG level rather than at the individual port level, reducing the overall system complexity while maintaining effective flow control through pause frames.
Data Source
AI summary
Methods for providing flow control of signal streams over a single full duplex ETHERNET link include receiving multiple data streams over a single ETHERNET link, associating a buffer with each data stream, putting received data into the appropriate buffer, monitoring the fullness of the buffers, and transmitting a PAUSE frame to the source of the data streams where the PAUSE frame indicates the fullness of each buffer. The PAUSE frame is read and where indicated, the transmission of data destined for a congested buffer(s) is halted until a subsequent PAUSE frame is received which indicates that the congested buffer(s) has become decongested. Apparatus for performing the methods are also provided.