Per-VSN Multicast Trees for ISIS-SPB LSDB Distribution

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Solution Overview

Problem

Conventional Shortest Path Bridging (SPB) networks face limitations in database size, control plane chatter, and operational complexity due to the use of multiple protocols, which leads to slower convergence and increased computational load, especially in multi-tenant environments where virtualized services require additional Type Length Value (TLV) assignments and limited LSDB space.

Innovation Solution

The implementation of per Virtual Services Network (VSN) multicast trees for virtualizing ISIS-SPB Link State Database (LSDB) updates, allowing for separate instances of the control protocol to distribute routing information only to relevant members, thereby reducing computational load and eliminating unnecessary control plane chatter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple protocols (BGP, OSPF, ISIS) are used in the transport network, then routing information can be exchanged for different services, but the device complexity and operational complexity increase significantly

Engineering Contradiction:

Improverouting information exchange capabilityVSAvoidprotocol configuration and management complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent makes ISIS protocol multi-functional by enabling it to carry both traditional link-state routing information and BGP-like service routing information through a single protocol instance. The ISIS protocol is enhanced to encode service routing attributes (such as I-SID, service type, reachability information) within its existing Link State PDU structure, eliminating the need for separate BGP protocol instances while maintaining adaptability for multiple service types including L2VSN, L3VSN, and multicast services

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If BGP protocol is used for service routing exchange, then service reachability information can be advertised, but the convergence speed slows down due to multiple protocol convergence requirements

Engineering Contradiction:

Improveservice routing advertisement capabilityVSAvoidnetwork convergence speed

Core Design Contradiction:

Adaptability or versatilityVSSpeed

Solution Approach 1:

The patent merges the service routing advertisement function (traditionally handled by BGP) with the link-state routing protocol (ISIS) into a single unified protocol instance. By encoding service routing information as ISIS Link State PDU types, the system eliminates the need for separate BGP session establishment and convergence, allowing service routing updates to propagate at ISIS convergence speed through the same link-state database mechanism

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If per-VSN routing information is distributed through a single shared LSDB, then database management is simplified, but the LSDB size limitation restricts the amount of routing information that can be stored

Engineering Contradiction:

Improvedatabase management simplicityVSAvoidrouting information storage capacity

Core Design Contradiction:

Ease of operationVSQuantity of substance

Solution Approach 1:

The patent segments the routing information storage by creating separate ISIS LSDB instances for each Virtual Services Network (VSN). Each VSN maintains its own isolated Link State Database with dedicated Link State PDU types, allowing unlimited growth of routing information per VSN without affecting other VSNs. The system manages multiple independent LSDB instances, each with its own size capacity, while maintaining operational simplicity through automated instance creation and isolation

Inventive Principle:

Principle #1Segmentation

4Ease of operation

If a single shared LSDB is used for all VSNs, then database management is simpler, but control plane chatter increases as updates are propagated to all nodes

Engineering Contradiction:

Improvedatabase management simplicityVSAvoidcontrol plane processing load

Core Design Contradiction:

Ease of operationVSLoss of energy

Solution Approach 1:

The patent segments the control plane information distribution by creating separate ISIS LSDB instances for each VSN. Routing updates for a specific VSN are propagated only to nodes that are members of that VSN, rather than flooding all updates to every node in the network. This isolation reduces control plane chatter and processing load on core devices while maintaining simple database management through automated instance handling

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9413637B2Architecture for virtualization and distribution of routing information used in a transport network

Publication Date: 2016.08.09 EXTREME NETWORKS INC

AI summary

A method, apparatus and computer program product for distribution of routing information used in a transport network is presented. In a transport network having a plurality of edge devices and core devices, a main instance of a protocol is used for shortest path and tree computation. A multicast tree is defined per Virtual Services Network (VSN) to distribute Link State Data Base (LSDB) updates that only apply to members of said VSN. Multicast trees are built using a secondary instance of the control protocol LSDB and wherein each VSN multicast tree represents a separate instance of the secondary instance of the control protocol LSD. LSDB updates are distributed that only apply to members of the VSN using the multicast tree for the VSN.