Dynamic Token Holding Time for Asymmetric Optical Networks
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Solution Overview
Problem
Conventional multi-token protocols for optical communications networks face challenges in handling asymmetrical traffic, leading to impaired performance due to fixed token holding times, resulting in unfairness and high latency, especially in video on demand applications where bandwidth requirements are asymmetrical.
Innovation Solution
Implementing a node with a transmit controller that dynamically determines the remaining token holding time after initial packet transmission, allowing further packets to be forwarded based on this time, and potentially using different token holding times for different nodes and channels to manage queue delays and fairness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed token holding time is used in multi-token protocols, then network control is simplified, but packet delay increases and bandwidth utilization deteriorates
Solution Approach 1:
The patent applies dynamics by making the token holding time variable rather than fixed. The transmit controller dynamically adjusts the token holding time based on real-time buffer status and traffic conditions, allowing the system to adapt to changing network demands while maintaining simple control mechanisms.
Solution Approach 2:
The invention changes the parameter of token holding time from a static fixed value to a dynamic variable that is adjusted based on buffer occupancy and traffic conditions. This parameter change enables the system to optimize packet delay and bandwidth utilization without significantly increasing control complexity.
2Speed
If all packets are forwarded to transmitter immediately upon receiving token, then transmission speed is maximized, but out-of-sequence delivery risk increases and fairness deteriorates
Solution Approach 1:
The patent applies preliminary action by having the transmit controller determine the token holding time in advance based on buffer status before packets are forwarded to the transmitter. This preliminary determination ensures that packets are transmitted in the correct sequence and prevents out-of-sequence delivery while maintaining efficient transmission.
3Ease of operation
If uniform token holding time is applied to all nodes, then network fairness is simplified, but asymmetrical traffic performance deteriorates
Solution Approach 1:
The patent applies local quality by allowing each node to have customized token holding times based on its specific traffic conditions and buffer status. Instead of uniform token holding times across all nodes, each node adapts its token holding time locally to match its asymmetrical traffic patterns, improving overall network productivity while maintaining operational simplicity through distributed control.
Data Source
AI summary
A node (260, 50) for a multi-token optical communications network has optical channels between the node and other nodes, each channel having a token (T1, T2, T3), passed between nodes, to indicate that a corresponding optical channel is available for transmission during a token holding time. The node has a transmitter (280) for transmitting packets over the optical channels, a buffer (170, 270) for queuing packets before transmission, and a transmit controller (170, 290) configured to control the buffer to forward an initial packet or packets from the buffer to the transmitter once a token has been received. The transmit controller determines how much of the token holding time remains after the transmission of the initial packet or packets, and then controls the buffer to forward a further packet according to the remaining token holding time. A maximum packet delay can be reduced where there is asymmetric traffic. A token holding time can be different for different nodes.