Multicast Traffic Loop Prevention in SPBM Networks

Solution Overview

Problem

Current SPBM network implementations in multi-homed environments limit the Ingress Backbone Edge Bridge to a single BVLAN for multicast traffic, leading to inefficiencies due to duplication and looping issues, as the rule for traffic blocking is based on BVLANs, restricting the use of multiple BVLANs for traffic forwarding.

Innovation Solution

The method allows the Ingress BEB to choose any available BVLAN for forwarding multicast traffic and includes a rule optimization where, if the nickname in a packet matches a multihomed partner's nickname, copies are not made for multihomed ADs, enabling the use of multiple BVLANs and preventing duplication and looping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the conventional rule blocks multicast traffic based on BVLAN at the Egress BEB, then duplication and looping of multicast traffic is prevented, but the Ingress BEB is limited to using only a single BVLAN for multicast traffic forwarding

Engineering Contradiction:

ImproveNumber of BVLANs usable by Ingress BEBVSAvoidTraffic blocking rule complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent changes the blocking parameter from BVLAN-based to nickname-based. Instead of blocking traffic based on which BVLAN a packet arrives on, the Egress BEB now checks whether the nickname in the packet matches its own nickname. If it matches, the Egress BEB blocks the packet from being forwarded to multi-homed UNIs. This parameter change allows the Ingress BEB to use multiple BVLANs freely while the Egress BEB intelligently prevents duplication using nickname comparison.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the Ingress BEB uses multiple BVLANs for multicast traffic, then network efficiency and traffic distribution improve, but traffic duplication and looping occur at the Egress BEB

Engineering Contradiction:

ImproveNetwork efficiencyVSAvoidTraffic duplication and looping

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent implements a feedback mechanism where the Egress BEB receives multicast packets from the Ingress BEB and checks whether the nickname in the packet matches its own nickname. This feedback loop allows the Egress BEB to recognize packets that have already been processed by the Ingress BEB and prevent them from being duplicated and forwarded to multi-homed UNIs, thereby eliminating traffic duplication while allowing multiple BVLAN usage.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The nickname acts as an intermediary identifier that carries information about the Ingress BEB through the network. By embedding the Ingress BEB's nickname in the packet and having the Egress BEB check this nickname, the system creates an intermediary mechanism that enables intelligent routing decisions without requiring complex signaling or control plane communication between BEBs.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the conventional BVLAN-based blocking rule is used, then traffic from external nodes is properly handled, but multi-homed UNIs receive duplicate traffic from cluster partners

Engineering Contradiction:

ImproveTraffic handling correctnessVSAvoidDuplicate traffic to multi-homed UNIs

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the blocking parameter from BVLAN-based to nickname-based. Instead of blocking traffic based on which BVLAN a packet arrives on, the Egress BEB now checks whether the nickname in the packet matches its own nickname. If it matches, the Egress BEB blocks the packet from being forwarded to multi-homed UNIs. This parameter change allows the Ingress BEB to use multiple BVLANs freely while the Egress BEB intelligently prevents duplication using nickname comparison.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9584333B2Optimization of rules used for prevention of duplication and looping of multicast traffic within a multi-homed cluster of backbone edge bridges in a shortest path bridging multicast network

Publication Date: 2017.02.28 EXTREME NETWORKS INC

AI summary

A method, apparatus and computer program product for prevention of duplication and looping of multicast traffic within a multi-homed cluster of backbone edge bridges is presented. Multicast traffic is received on a first Access device (AD). The multicast traffic is forwarded from the first AD to a first Backbone edge Bridge (BEB). Any available Backbone Virtual Local Area Network (BVLAN) is chosen to forward the multicast traffic into a transport network by the first BEB. The multicast traffic is received at a second BEB from said first BEB. A determination is made whether a nickname in a packet of the multicast traffic is a nickname of the first BEB and when the nickname in the packet matches a nickname of the first BEB then abstaining from making copies of said packet for said first AD and said second AD.