Optical Network Host Nodes Limiting LSA Propagation
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Solution Overview
Problem
Extending control plane functions to the network edge in optical transport networks leads to a proliferation of Link State Advertisement (LSA) traffic and large topology databases, degrading topology discovery, route computation, and failure recovery functions.
Innovation Solution
Implementing control plane functionality in tail nodes and controlling the size and propagation of LSA messages through host nodes, using summary information and connectivity vectors to advertise reachability of tail nodes, thereby reducing control plane messaging and maintaining efficient network operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If control plane functions are extended to all network nodes including tail nodes, then network coverage and node participation are improved, but control plane messaging volume and topology database size increase excessively
Solution Approach 1:
The network is segmented into core domain and metro domain with distinct node roles (core nodes, host nodes, tail nodes). Control plane functionality is segmented such that tail nodes have limited participation while core nodes handle full control plane operations. This segmentation allows tail nodes to participate in control plane operations without requiring full control plane capability at each node, thereby reducing overall messaging volume.
Solution Approach 2:
Host nodes act as intermediaries between tail nodes and the core control plane. Tail nodes communicate control plane information through their host nodes, which aggregate and forward this information to core nodes. This intermediary mechanism allows tail node participation while reducing the total control plane messaging by consolidating communications at host node level.
2Reliability
If full control plane capability is provided at each node, then routing flexibility and failure recovery are improved, but network complexity and processing overhead increase
Solution Approach 1:
Different nodes are assigned different levels of control plane capability based on their role and importance. Core nodes have full control plane capability for complex routing and failure recovery decisions. Host nodes have intermediate capability for local metro domain management. Tail nodes have minimal capability for basic participation. This local quality differentiation maintains reliability through distributed intelligence while reducing overall network complexity.
Solution Approach 2:
Tail nodes perform partial control plane functions through their host nodes rather than implementing full control plane capability. This partial action approach provides sufficient failure recovery capability for edge nodes without the full complexity of complete control plane implementation, achieving adequate reliability with reduced node complexity.
3Quantity of substance
If summary information and connectivity vectors are used to represent tail nodes, then control plane messaging is reduced, but information precision and route computation accuracy may be affected
Solution Approach 1:
Multiple tail nodes are merged into a single summary representation at the host node level. Instead of advertising individual tail node topologies separately, the host node aggregates tail node information into summary LSAs that represent groups of tail nodes. This merging reduces control plane messaging volume while maintaining sufficient precision for route computation through the summary representations.
Solution Approach 2:
The representation of tail nodes transitions from individual node-level detail to aggregated domain-level summary information. Summary LSAs provide a higher-dimensional abstraction that captures essential routing information for multiple tail nodes without the granularity of individual node advertisements. This dimensional change reduces messaging while preserving route computation accuracy through the abstracted representation.
Data Source
AI summary
A method of extending the control plane to a metro sub-domain for a network having a transport plane for carrying subscriber traffic within end-to-end connections, and a control plane for managing at least a portion of resources of the transport plane allocated to the connections. A first set of control-plane enabled nodes of the network is designated as core nodes, each core node being operable to route subscriber traffic between a pair of neighbor core nodes in the network. A second set of control-plane enabled nodes of the network is designated as metro nodes, each metro node being connected to a core node and operating as a sub-domain of the network. Each core node that is connected to at least one metro node is designated as a host node. The host node is controlled to advertise summary information of its connected metro nodes to other core and metro nodes in the network, thus making it possible to extend control plane function to the metro nodes that can calculate connection routes, set-up/tear-down connections and perform connection failure recovery functions.