Source Routing Protection Switching via Liveness Probes
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Solution Overview
Problem
Source routing networks that do not support per connection routing states face challenges in maintaining network path liveness and switching between primary and backup paths, especially in scenarios where tandem nodes operate with stateless connections.
Innovation Solution
A protection scheme is implemented in source routing networks that uses liveness protection probes to determine the connectivity status of network paths, allowing for seamless switching between primary and backup paths without requiring tandem nodes to maintain per connection routing states, by transmitting probes from an ingress node to an egress node and reflecting them back, enabling dynamic path switching based on probe responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If source routing networks use stateless tandem nodes for simplified operation, then ease of operation is improved, but the ability to detect and respond to network path failures deteriorates
Solution Approach 1:
Liveness protection probes serve as intermediaries between ingress and egress nodes to detect network path failures. These probe packets traverse the network path and return to the ingress node, enabling failure detection without requiring stateful tandem nodes. The probes act as a mediator that carries connectivity status information through the stateless network path.
Solution Approach 2:
The system implements feedback through the return journey of liveness protection probes from egress to ingress nodes. When probes successfully return, they provide positive feedback confirming path liveness. When probes fail to return within a timeout period, they provide negative feedback indicating path failure, enabling the ingress node to switch to backup paths.
2Reliability
If the network maintains per connection routing states for reliable path monitoring, then network path failure detection is improved, but device complexity increases
Solution Approach 1:
The patent extracts the state maintenance requirement from tandem nodes and concentrates it only at the ingress node. The ingress node maintains connection state and sends liveness protection probes, while tandem nodes remain stateless and simply forward packets based on connection identifiers. This extraction eliminates the complexity of per-connection state maintenance from most network elements.
Solution Approach 2:
The system uses probe packets as copies to monitor network path status. Instead of maintaining complex state at every node, the ingress node creates probe copies that traverse the network path and return with status information. This copying mechanism provides reliable failure detection without requiring persistent state at intermediate nodes.
3Measurement precision
If source routing uses strict path specification for precise routing control, then routing precision is improved, but adaptability to network failures deteriorates
Solution Approach 1:
The system performs preliminary action by pre-configuring backup paths and liveness protection probes before failures occur. The ingress node maintains both primary and backup connection identifiers and continuously sends probes to detect failures. When failures are detected, the system can immediately switch to pre-configured backup paths without complex real-time routing calculations.
Solution Approach 2:
The system implements dynamics by enabling the ingress node to dynamically switch between primary and backup paths based on real-time probe results. While the source routing headers specify fixed paths for individual packets, the ingress node can dynamically change which path (primary or backup) receives new traffic flows based on detected network conditions, providing adaptability while maintaining routing precision.
Data Source
AI summary
A network element configured to operate in a source routing network, wherein the network element comprises a receiver, a transmitter, and a processor coupled to the receiver and the transmitter. The processor may be configured to cause the network element to receive from an upstream network element, a liveness protection probe comprising a header that comprises a list of one or more ordered connection identifiers that indicate a network path traversing the source routing network through which the liveness protection probe should be forwarded, transmit the liveness protection probe toward a downstream network element according to the connection identifiers, receive the liveness protection probe from the downstream network element, and transmit the liveness protection probe to the upstream network element according to a second list of one or more ordered connection identifiers contained within the header.