GFP Command Field for Transparent APS Signaling
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Solution Overview
Problem
Current automatic protection switching (APS) in SONET and SDH networks is limited by the restricted information capacity of K1 and K2 bytes, which are not transparent to the SONET or SDH cloud, restricting the amount of protection switch information that can be transmitted.
Innovation Solution
The method involves incorporating protection switch information into a command field of a Generic Framing Procedure (GFP) frame, allowing up to four bytes of information to be transmitted transparently across the network, using a GFP frame with a payload area that includes a command field for channel selection and priority information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If K1 and K2 bytes are used for protection switching signaling, then the signaling can be implemented within the existing SONET/SDH overhead structure, but the information capacity is limited to only two bytes
Solution Approach 1:
The patent transitions from using overhead bytes (K1, K2) in the traditional dimension to embedding protection switching information within the payload data stream dimension. Specifically, it uses the first byte of the payload data following the GFP header to carry protection switching signals, effectively utilizing an underused resource dimension within the existing frame structure.
Solution Approach 2:
The patent makes the payload data field serve multiple functions: it carries both the actual user data and the protection switching signaling information simultaneously. The first byte of the payload is dual-purpose, serving as both data transport and APS signaling carrier, thereby eliminating the need for dedicated signaling bytes.
2Reliability
If K1 and K2 bytes are used for protection switching, then the signaling is integrated into the line overhead, but the information is not transparent to the SONET or SDH cloud
Solution Approach 1:
The patent introduces the payload data field as an intermediary carrier for protection switching information. Instead of using overhead bytes that are processed and potentially blocked by network elements, the APS signals are embedded within the payload data stream, allowing them to pass transparently through the SONET/SDH cloud without being intercepted or modified by network equipment.
3Adaptability or versatility
If only two bytes (K1 and K2) are allocated for protection switching information, then the signaling structure remains simple, but the amount of protection switch information that can be transmitted is restricted
Solution Approach 1:
The patent changes the parameter for information capacity by utilizing the payload data field which can accommodate up to 65,535 bytes, compared to the limited two-byte K1 and K2 overhead structure. This parameter change enables comprehensive transmission of protection switching information including channel selection, priority, and status details without restricting the information capacity.
Data Source
AI summary
Methods and apparatus for efficiently allowing protection switch information to be communicated on bidirectional lines are disclosed. According to one aspect of the present invention, a method for communicating protection switch information from a first network element to a second network element across bidirectional links that include at least one working line and a protection line involves obtaining a generic framing procedure GFP frame at the first network element. The GFP frame has a payload area with a client payload field. The method also includes defining a command field associated with the GFP frame that is in the payload area but not in the client payload field, and storing protection switch information in the command field.