Multicast Packet Forwarding via Pre-calculated Distribution Trees

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Solution Overview

Problem

In very large layer 2 (VLL2) networking in data centers, existing technologies face challenges in efficiently forwarding multicast data packets across multiple virtual local area networks (VLANs) using TRILL networks, particularly in maintaining router ports and gateway information, which affects the reliability and efficiency of multicast data distribution.

Innovation Solution

The proposed solution involves a method for obtaining nicknames of designated routers in each VLAN, calculating distribution trees, and using TRILL multicast trees to determine DR and gateway router ports, enabling efficient forwarding of multicast data packets by encapsulating them into PIM register packets and managing membership information across VLANs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If TRILL decapsulation and encapsulation are performed for multicast data packets, then multicast data can be forwarded across VLANs, but the forwarding efficiency decreases and network availability is reduced

Engineering Contradiction:

Improveforwarding efficiencyVSAvoidnetwork availability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent pre-calculates distribution trees and determines DR and gateway router ports before multicast data needs to be forwarded. This preliminary setup of routing information allows packets to be forwarded directly without time-consuming decapsulation and encapsulation operations, thereby improving forwarding efficiency while maintaining network availability through pre-established reliable paths

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If router ports are maintained for each VLAN, then accurate multicast routing is achieved, but device complexity increases

Engineering Contradiction:

Improverouting accuracyVSAvoidrouter port management

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the management of router ports across multiple VLANs by calculating distribution trees that span VLAN boundaries. Instead of maintaining separate router port information for each VLAN, the system consolidates this information into unified distribution trees rooted at designated routers, reducing device complexity while maintaining routing accuracy through the hierarchical structure of the trees

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The distribution trees serve multiple functions simultaneously: they provide routing paths for multicast data, encode VLAN identification information, and define the hierarchy of designated routers. This multi-functionality eliminates the need for separate router port maintenance for each VLAN, reducing complexity while preserving routing precision through the universal tree structure

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9509522B2Forwarding multicast data packets

Publication Date: 2016.11.29 HEWLETT PACKARD ENTERPRISE DEV LP

AI summary

A gateway routing bridge of a data center, obtains nicknames of designated routers (DR) of a multicast group in each virtual local area network (VLAN); calculates distribution trees rooted at each DR; receiving a multicast data packet from a multicast source of the multicast group which inside the data center; and sends the multicast data packet on the distribution tree rooted at the DR which corresponds to a multicast address and a VLAN identifier (VLAN ID) of the multicast data packet.