OAM Path Impairment Notification Protocol
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Solution Overview
Problem
Existing techniques for signaling path impairment in data networks are inefficient or impractical, particularly in scenarios where multiple routing domains are involved, leading to delayed congestion detection and potential packet loss due to the inability of source nodes to receive timely and relevant impairment information from intermediate nodes.
Innovation Solution
Implementing a path impairment notification scheme where intermediate nodes selectively mark path impairment conditions on management packets, such as OAM connectivity frames or MPLS-Ping frames, only for source nodes interested in receiving this information, using reserved bits and specific control fields to indicate the type and severity of impairments, allowing source nodes to take corrective actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If intermediate nodes mark all OAM frames with congestion information, then source nodes receive complete congestion notifications, but network overhead increases significantly
Solution Approach 1:
The patent applies local quality by selectively marking OAM frames based on the specific characteristics of each source node. Intermediate nodes examine the source node address and determine whether to mark congestion information on a per-source-node basis, rather than uniformly marking all frames. This allows the system to provide congestion notifications only to source nodes that need and can act on this information, thereby reducing overall network overhead while maintaining reliability for interested sources.
2Reliability
If ECN marking is implemented on all transit nodes, then congestion detection coverage is improved, but implementation complexity increases due to existing EXP bit usage for priority marking
Solution Approach 1:
The patent segments the congestion notification function by separating it from the existing EXP bit priority marking function. Instead of attempting to multiplex both functions into the same bit field (which would increase complexity), the invention uses dedicated congestion notification mechanisms that operate independently. This segmentation allows transit nodes to implement congestion detection without conflicting with existing priority marking implementations, thereby improving coverage without significantly increasing device complexity.
3Ease of operation
If source nodes receive detailed congestion information from intermediate nodes, then corrective actions can be more precisely targeted, but information processing overhead at source nodes increases
Solution Approach 1:
The patent extracts only the essential congestion notification information from the OAM frames and delivers it to source nodes, rather than transmitting complete detailed congestion data. The intermediate nodes perform preliminary processing to extract key congestion indicators (such as simple mark bits) and remove extraneous detailed information. This extraction approach enables source nodes to take precise corrective actions based on the essential information provided, while minimizing the information processing overhead at source nodes by eliminating unnecessary data.
Data Source
AI summary
An apparatus comprising a node configured to transmit operation, administration, and maintenance (OAM) connectivity frames, wherein the node adds an impairment notification indication to some, but not all of OAM connectivity frames transmitted by the node, wherein the impairment notification indication indicates the node's desire to receive notification of an impairment condition along the path. A network component comprising a receiver unit configured to receive multiprotocol label switching (MPLS) Ping frames, a circuit logic configured to add a downstream link impairment indication to responses to the MPLS-Ping frames, wherein the downstream link impairment indication comprises a type and a severity level for a path impairment condition, and a transmitter unit configured to transmit the responses to the transmitted MPLS-Ping frames.