Upstream Label Assignment for MPLS P2MP LSPs

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Solution Overview

Problem

In computer networks, especially with growing size and complexity, traffic congestion occurs due to approaching maximum bandwidth capacity on links, leading to inefficiencies in routing and traffic replication within Local Area Networks (LANs) for Multi-Protocol Label Switching (MPLS) Point to Multi-Point (P2MP) Label Switched Paths (LSPs).

Innovation Solution

Extensions to the Label Distribution Protocol (LDP) enable upstream label assignment, allowing routers to distribute labels to multiple downstream routers, avoiding traffic replication on LANs by using upstream assigned labels for MPLS P2MP LSPs, and enabling the binding of labels to tunnels through a tunnel identifier, facilitating efficient multicast traffic transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traffic replication is performed on LANs for MPLS P2MP LSPs, then multiple downstream routers can receive multicast packets, but bandwidth utilization becomes inefficient due to duplicate traffic on the same link

Engineering Contradiction:

Improvebandwidth utilizationVSAvoidbandwidth waste

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent merges multiple downstream label requests into a single upstream label assignment. The head-end router assigns a single upstream label that is distributed to multiple downstream routers, eliminating the need for separate label assignments and traffic replication on LAN segments. This combines what would otherwise be separate unicast flows into a single efficient multicast flow.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent inverts the traditional downstream-to-upstream label assignment flow. Instead of each downstream router requesting and receiving individual labels from upstream routers, the upstream head-end router proactively assigns labels downstream and distributes them to multiple downstream routers. This upstream-initiated approach eliminates redundant traffic replication.

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of operation

If traditional LDP downstream label assignment is used, then label distribution can be performed, but traffic replication occurs on LANs leading to congestion and loss

Engineering Contradiction:

Improvelabel distributionVSAvoidtraffic congestion

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent introduces an intermediary mechanism where the head-end router acts as a central coordinator for label distribution. It assigns upstream labels and distributes them to multiple downstream routers through a controlled process, preventing uncontrolled traffic replication. The intermediary controls the label assignment process to ensure efficient bandwidth utilization.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent performs preliminary label assignment at the head-end router before traffic flow is established. By pre-assigning upstream labels and distributing them to downstream routers in advance, the system prevents the need for runtime traffic replication, thereby avoiding congestion and loss during actual data transmission.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If upstream label assignment is implemented, then bandwidth efficiency is improved by avoiding traffic replication, but LDP protocol complexity increases

Engineering Contradiction:

Improvenetwork efficiencyVSAvoidprotocol complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent creates a universal upstream label assignment mechanism that can serve multiple downstream routers simultaneously. A single upstream label assignment process handles distribution to multiple downstream routers, making the protocol multi-functional. This universal approach reduces overall system complexity compared to individual label assignments for each downstream router.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent changes the label assignment parameter from downstream-specific individual labels to a unified upstream label that is distributed to multiple downstream routers. This parameter change simplifies the label distribution process while maintaining the ability to serve multiple downstream destinations, improving network efficiency without proportionally increasing complexity.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8488614B1Upstream label assignment for the label distribution protocol

Publication Date: 2013.07.16 HEWLETT PACKARD ENTERPRISE DEV LP

AI summary

The invention is directed toward techniques for Multi-Protocol Label Switching (MPLS) upstream label assignment for the Label Distribution Protocol (LDP). The techniques include extensions to the LDP that enable distribution of upstream assigned labels from an upstream router to two or more downstream routers of a tunnel established over a network. The tunnel may comprise a LDP Point to Multi-Point (P2MP) Label Switched Path (LSP), an Internet Protocol (IP) multicast tunnel, or a Resource Reservation Protocol with Traffic Engineering extensions (RSVP-TE) P2MP LSP. The techniques also include extensions to the LDP that enable a router to advertise upstream label assignment capability to neighboring routers in the network. The MPLS upstream label assignment using LDP described herein enables a branch router to avoid traffic replication on a Local Area Network (LAN) for LDP P2MP LSPs.