Inter-Frame Time Field for Pacing Preservation

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Solution Overview

Problem

Current methods for preserving data link layer pacing information across transport media, especially in geographically dispersed networks, are complex, costly, and introduce latency, as they often require protocol termination or synchronous transparency, limiting connectivity options and increasing costs.

Innovation Solution

A protocol encapsulation technique that encodes the time between frames in an inter-frame time field, allowing for comparison with a counter at the receiving destination, ensuring reliable pacing information preservation across transport media at varying rates, including those different from the native protocol rate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If protocol termination or synchronous transparency is used to preserve pacing information, then pacing information can be maintained, but device complexity and cost increase

Engineering Contradiction:

Improvepacing information preservationVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts only the essential pacing information (inter-frame time) from the protocol and encapsulates it separately in an inter-frame time field. This allows the pacing information to be preserved without requiring full protocol termination or synchronous transparency, thereby reducing device complexity while maintaining reliability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention segments the protocol into data payload and control information (inter-frame time field). By separating the timing information from the data stream, the system can preserve pacing without requiring complex protocol handling, thus reducing device complexity while maintaining pacing information integrity.

Inventive Principle:

Principle #1Segmentation

2Reliability

If protocol termination is used to preserve pacing information, then pacing information can be maintained, but cost increases

Engineering Contradiction:

Improvepacing information preservationVSAvoidcost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention uses a simple, lightweight inter-frame time field that can be easily implemented and discarded after use. This approach avoids the need for expensive protocol termination handling while still achieving reliable pacing information preservation across the transport medium.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If synchronous transparency is used to preserve pacing information, then pacing information can be maintained, but connectivity options are limited

Engineering Contradiction:

Improvepacing information preservationVSAvoidconnectivity options

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention creates a universal inter-frame time field that can be appended to frames of different protocols (SBCON, Fibre Channel, ESCON, GbE, etc.). This allows a single transport medium to support multiple protocols with different rates while preserving pacing information, thereby expanding connectivity options rather than limiting them.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention enables dynamic rate adaptation by allowing the inter-frame time field to accommodate different frame rates. The system can dynamically adjust to various transport rates (e.g., OC-3, OC-12, OC-48) while maintaining pacing information integrity, thus providing versatility across different connectivity scenarios.

Inventive Principle:

Principle #15Dynamics

4Reliability

If protocol translation and device spoofing are used, then pacing information can be preserved, but processing capacity and cost increase

Engineering Contradiction:

Improvepacing information preservationVSAvoidprocessing capacity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention creates a simplified copy of the pacing information in the form of an inter-frame time field that mirrors the original protocol's timing characteristics. This copying approach preserves pacing without requiring complex protocol translation or device spoofing, thereby maintaining processing capacity while ensuring reliability.

Inventive Principle:

Principle #26Copying

5Reliability

If latency is introduced for protocol interactions, then pacing information can be preserved, but transmission time increases

Engineering Contradiction:

Improvepacing information preservationVSAvoidlatency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The invention performs preliminary action by pre-calculating and encoding the inter-frame time field at the transmitting end before frame transmission. This allows the receiving end to immediately use the encoded timing information without requiring additional protocol interactions or latency, thus preserving pacing information while minimizing transmission time.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS7539209B2Method and device for preserving pacing information across a transport medium

Publication Date: 2009.05.26 CIENA CORP

AI summary

The invention relates to data communications, more particularly to a protocol encapsulation technique which captures the time between frames at a transmitting site for comparison with an idle counter at a receiving site. At the originating site, the time between successive frames in the native protocol is encoded in an interframe time field associated with each respective frame, before the time encoded frame is mapped into the protocol associated with the transport medium. At the destination site, the framing associated with the transport medium is removed to reveal the interframe time field. The value contained in this field is compared with the value of an idle counter running at the native protocol rate. When the idle count is greater than or equal to the encoded inter-frame time, the data contained in the frame is then delivered to the client.