PITP Protocol for BRAS Layer 2 Encapsulation Mode Transfer
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Solution Overview
Problem
Broadband remote access servers (BRAS) lack knowledge of subscriber line Layer 2 encapsulation modes, which affects the accuracy of quality of service (QoS) scheduling, and existing solutions increase workload and resource overhead in DSLAM by requiring differentiation of access modes through PPP or DHCP operations.
Innovation Solution
The subscriber line Layer 2 encapsulation mode is transferred to the BRAS using a policy information transfer protocol (PITP) packet, either by the DSLAM actively reporting the mode when preset conditions are met or by the BRAS initiating an inquiry, allowing the BRAS to adjust QoS scheduling without differentiating access modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the DSLAM inserts Layer 2 encapsulation mode options into PPP or DHCP operations to inform the BRAS, then the BRAS can know the subscriber line Layer 2 encapsulation mode, but the workload of the PPP or DHCP module and the resource overhead of the DSLAM are increased
Solution Approach 1:
The patent introduces a new intermediary protocol (PITP - Policy Information Transfer Protocol) between the DSLAM and BRAS to transfer Layer 2 encapsulation mode information. This intermediary protocol专门 handles the information transfer function, separating it from the existing PPP/DHCP processing paths, thereby avoiding the complexity increase in those modules while still achieving the goal of informing the BRAS about encapsulation modes
Solution Approach 2:
The patent segments the information transfer function from the access mode differentiation function. Instead of handling all information transfer within PPP/DHCP operations, the patent extracts the Layer 2 encapsulation mode transfer into a separate PITP protocol, allowing the DSLAM to use a unified approach regardless of whether the subscriber accesses via PPP or DHCP
2Measurement precision
If the DSLAM differentiates access modes (PPP or DHCP) to insert Layer 2 encapsulation mode options, then the BRAS receives accurate encapsulation mode information, but the workload of the DSLAM is increased
Solution Approach 1:
The patent makes the PITP protocol universal for transferring Layer 2 encapsulation mode information regardless of the underlying access mode (PPP or DHCP). The DSLAM uses the same PITP mechanism for both access types, eliminating the need for separate processing paths and differentiation logic, thereby improving processing efficiency while maintaining information accuracy
Data Source
AI summary
The present invention provide two methods for transferring a subscriber line Layer 2 encapsulation mode to a broadband remote access server (BRAS) by a broadband subscriber access device, of which the key point is using a policy information transfer protocol (PITP) to transfer the subscriber line Layer 2 encapsulation mode to the BRAS, and thus enables the BRAS to know the Layer 2 encapsulation mode of the accessed subscriber so as to prevent the accuracy of QoS scheduling from being influenced by different overhead caused by different Layer 2 encapsulation modes of the subscriber line. Therefore, the DSLAM does not need to differentiate accessing modes of the subscribers, which reduces the DSLAM resource overhead and meanwhile reduces the workload of the PPP or DHCP module. In addition, the prevent invention provide two implementation manners, namely, active and passive manners, which makes the specific applications are more flexible.