BSID Traceroute Proxy for Hop-by-Hop LSP Tracing
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Solution Overview
Problem
Current LSP traceroute mechanisms fail to trace network nodes in an LSP represented by a Binding Segment Identifier (BSID) in a hop-by-hop manner, especially in the short pipe model, where network nodes within the same administrative domain are not effectively traced.
Innovation Solution
A method where a network node advertising a BSID responds to an echo request with an indicator to replace the FEC with a set of FECs, allowing the initiating node to transmit further echo requests with the new FEC stack, enabling the advertising node to act as a proxy for tracing network nodes along the LSP, thereby achieving hop-by-hop tracing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the short pipe model is used for BSID, then the network node advertising BSID can simplify forwarding operations, but the ability to trace network nodes in LSP hop-by-hop is lost
Solution Approach 1:
The patent introduces an indicator as an intermediary element in the echo reply packet. This indicator signals to the initiating node that the FEC should be replaced by a set of FECs, enabling the traceroute to continue hop-by-hop tracing without requiring the advertising node to change its short pipe forwarding behavior. The indicator mediates between the simplified forwarding model and the detailed tracing requirement.
Solution Approach 2:
The patent segments the FEC stack by introducing a mechanism to replace a single FEC with a set of FECs. This segmentation allows the traceroute to break down the LSP into individual hops for detailed tracing, while the network maintains the simplified short pipe forwarding model. The FEC stack is divided into replaceable segments that can be expanded when tracing is needed.
2Measurement precision
If the uniform model is used for TTL processing, then hop-by-hop tracing is enabled, but it is incompatible with the short pipe model which is desired for scalability
Solution Approach 1:
The patent makes the FEC stack dynamic by allowing it to be replaced with a set of FECs based on the indicator received in the echo reply. This dynamic behavior enables the system to adapt between tracing mode (where detailed FEC stacks are used) and normal operation mode (where simplified short pipe forwarding is used), without being locked into a single static model.
Solution Approach 2:
The patent changes the parameter of the FEC stack from a single FEC to a set of FECs based on the indicator. This parameter change allows the system to switch between different operational modes - when the indicator is present, the FEC stack is expanded to enable tracing; when absent, the simplified model is maintained. This resolves the incompatibility between uniform model tracing and short pipe model scalability.
3Device complexity
If a single FEC is used in the FEC stack, then the data plane is simplified, but the ability to trace intermediate network nodes is lost
Solution Approach 1:
The patent prepares the FEC stack in advance by keeping it as a single FEC for normal simplified operation, but includes the indicator in the echo reply that triggers the replacement with a set of FECs. This preliminary setup allows the system to maintain simplicity while having the detailed tracing information ready to be activated when needed, preventing loss of intermediate node information only when required.
Data Source
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AI summary
The present disclosure provides a method (100) in a network node advertising a Binding Segment Identifier, BSID. The method (100) includes: receiving (110) a first echo request packet containing a first target Forwarding Equivalence Class, FEC, stack including an FEC associated with the BSID; and transmitting (120), in response to a Time To Live, TTL, expiration associated with the first echo request packet, a first echo reply packet to an initiating network node initiating the first echo request packet, the first echo reply packet containing an indicator indicating that the FEC is to be replaced by a set of FECs.