OSPF ISIS Bypass Path Selection for Network Reliability
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Solution Overview
Problem
Multi-topology networks fail to utilize resource reservation protocol (RSVP) multiprotocol label switching (MPLS) label-switched paths (LSPs) within and across clusters of network devices, as they are unable to select a bypass path from available paths based on different link state protocols like OSPF and ISIS, leading to traffic outages and resource wastage.
Innovation Solution
A network device that receives attributes identifying paths in OSPF and ISIS domains, determines the availability of primary paths, and selects secondary paths associated with either domain to route traffic when primary paths are unavailable, ensuring continuous traffic routing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-topology networks use RSVP MPLS LSPs within and across clusters, then traffic routing reliability is improved, but the ability to select bypass paths based on different link state protocols (OSPF and ISIS) is lost
Solution Approach 1:
The network is segmented into multiple topology domains (OSPF domain and ISIS domain), each with its own link state protocol. The system maintains separate path attributes for each domain, allowing independent path selection within each protocol domain while providing overall multi-domain traffic engineering capability.
Solution Approach 2:
The system pre-calculates and stores path attributes for both primary and secondary paths in each topology domain before failures occur. When a failure is detected, the system can immediately switch to a pre-identified secondary path within the same domain, eliminating the need for complex real-time protocol negotiation and enabling fast bypass path selection.
2Device complexity
If the network relies on a single primary path for traffic routing, then device complexity is reduced, but traffic outages occur when the primary path fails
Solution Approach 1:
The system prepares secondary paths in advance within each topology domain and stores their attributes locally. When a primary path failure occurs, the system can immediately activate a pre-prepared secondary path without complex real-time calculations, providing fault tolerance while maintaining relatively simple device complexity.
Solution Approach 2:
The patent introduces an intermediary mechanism that stores path attributes from multiple topology domains locally at each router. This intermediary layer abstracts the complexity of multi-protocol path selection, allowing simple local decision-making based on stored attributes while maintaining traffic continuity across domain boundaries.
3Reliability
If the network frequently switches between primary and secondary paths, then traffic continuity is maintained, but computing and networking resources are wasted
Solution Approach 1:
The system performs path calculations and stores secondary path attributes in advance within each topology domain. When failures occur, it only activates pre-prepared paths rather than performing new calculations, significantly reducing computing resource consumption during failover events while maintaining traffic continuity.
Solution Approach 2:
The system dynamically selects paths based on actual network conditions and failure scenarios, but only within the same topology domain. This dynamic selection is constrained to pre-identified domains, reducing the search space and computational overhead compared to unrestricted dynamic path selection across the entire network.
Data Source
AI summary
A network device receives an attribute identifying paths associated with an open shortest path first (OSPF) domain of a network and an intermediate system to intermediate system (ISIS) domain of the network, and provides the attribute to other network devices of the network. The network device receives traffic destined for one of the other network devices of the network, and determines that a primary path is unavailable for routing the traffic to the one of the other network devices. The network device selects a secondary path from the paths identified by the attribute. The secondary path is selected based on determining that the primary path is unavailable, and the secondary path is associated with the OSPF domain or the ISIS domain of the network. The network device provides the traffic to the one of the other network devices via the secondary path.