TDM CES Bandwidth Reduction via Jitter Buffer Control
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Solution Overview
Problem
Legacy TDM services in packet-switched networks continue to consume excessive bandwidth due to the transmission of invalid packets, even when the access circuit is not in a normal state, particularly in networks with limited bandwidth links like microwave communication and N×T1 channels in SONET.
Innovation Solution
A method where a transmitting router notifies a receiving router to halt packet transmission over a TDM-PW when the access circuit status is abnormal, and the receiving router generates packets to maintain the jitter buffer fill-level until normal conditions are restored.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transmitting router continues to send packets with invalid TDM data or empty payloads during abnormal access circuit conditions, then the receiving router can maintain continuous packet reception and jitter buffer fill-level, but network bandwidth is wasted due to transmission of unnecessary packets comprising mostly headers
Solution Approach 1:
The transmitting router sends a preliminary notification signal to the receiving router before stopping packet transmission. This notification allows the receiving router to proactively generate dummy packets to maintain jitter buffer fill-level, preventing buffer underrun while avoiding waste of bandwidth on actual data transmission during abnormal conditions.
Solution Approach 2:
The patent introduces a control signaling mechanism as an intermediary between transmitting and receiving routers. This signaling channel carries information about abnormal conditions and triggers the receiving router to generate local dummy packets, thereby decoupling the need for continuous packet flow from the need for actual data transmission.
2Loss of energy
If the transmitting router stops sending packets entirely during abnormal conditions, then network bandwidth is conserved, but the receiving router's jitter buffer may become empty causing service disruption
Solution Approach 1:
The receiving router is empowered to self-generate dummy packets locally when it receives notification of abnormal conditions. This self-service mechanism ensures the jitter buffer remains filled without requiring actual data transmission from the transmitting router, thus conserving bandwidth while maintaining service continuity.
3Loss of energy
If the transmitting router sends packets with suppression option enabled (no payload), then some bandwidth is saved compared to sending invalid data, but the header still constitutes up to 95% of packet size resulting in minimal bandwidth savings
Solution Approach 1:
The patent extracts the essential signaling function from the data packet transmission. By separating the notification of abnormal conditions from the actual data packets, the system eliminates the need to transmit unnecessary headers during abnormal conditions, achieving significant bandwidth savings while maintaining the control functionality.
Data Source
AI summary
A method and system are provided for reducing bandwidth usage in TDM CES systems. When a transmitting router receives a signal indicating that the access circuit is other than “normal”, and that therefore any TDM data arriving over the access circuit is not valid, the router signals a receiving router at the far end of a TDM Pseudowire that no packets will be sent and does not send any packets. When the receiving router receives such a signal it starts generating its own packets for placing in its jitter buffer. In this way, the jitter buffer maintains its fill level even when no packets are being sent. When the transmitting router receives notification indicating that its access circuit has returned to normal the router signals the receiving router that status has returned to normal, and begins sending packets again.