ESGW Packet Forwarding with PPPOE Encapsulation

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Solution Overview

Problem

Existing BRAS virtualization solutions cannot implement Point to Point Protocol over Ethernet (PPPOE) encapsulation while performing layer-3 forwarding for packets, limiting the functionality of gateway devices in comprehensive multi-service access edges.

Innovation Solution

An Edge Stream Gateway (ESGW) device decapsulates downstream packets, determines the session ID and length field of the PPPOE header, and encapsulates the packets into PPPOE data packets for forwarding through an egress port, enabling PPPOE encapsulation during layer-3 forwarding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If BRAS virtualization is implemented, then network service flexibility and adaptability are improved, but the ability to perform PPPOE encapsulation during layer-3 forwarding is lost

Engineering Contradiction:

Improvenetwork service flexibilityVSAvoidPPPOE encapsulation capability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent segments the packet processing function into two independent modules: a layer-3 forwarding module that handles IP packet routing, and a PPPOE encapsulation module that adds PPPOE headers. These modules operate independently but coordinate through shared data structures, allowing both layer-3 forwarding and PPPOE encapsulation to function simultaneously in the virtualized BRAS system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary mechanism in the form of a session information table that stores mapping relationships between session IDs and user information. This intermediary structure enables the layer-3 forwarding module to retrieve user information for PPPOE encapsulation without compromising forwarding performance, thus maintaining both virtualization benefits and PPPOE capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If layer-3 forwarding is performed, then packet routing efficiency is improved, but PPPOE encapsulation functionality is eliminated

Engineering Contradiction:

Improvepacket routing efficiencyVSAvoidPPPOE encapsulation functionality

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent performs preliminary actions by pre-storing user information and session mappings in the session information table before packet forwarding occurs. When a packet arrives, the layer-3 forwarding module quickly retrieves the necessary user information using the session ID, and the PPPOE encapsulation module immediately adds the appropriate header. This preliminary preparation enables both efficient forwarding and PPPOE encapsulation without sequential bottlenecks.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP3618393B1Packet forwarding

Publication Date: 2022.04.27 NEW H3C TECH CO LTD

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AI summary

According to an example of a method for forwarding a packet, an ESGW device decapsulates a received downstream data packet to obtain a downstream IP data packet when a destination MAC address of the downstream data packet is an MAC address of the ESGW device; determines a matching ARP entry of an IP address of a target user terminal based on the destination IP address of the downstream IP data packet to obtain a session ID of the target user terminal; determines a length field of a PPPOE header by a microcode, and obtains a pre-stored fixed-value field of the PPPOE header from a data storage area; encapsulates the downstream IP data packet into a downstream PPPOE data packet based on the session ID, the length field, and the fixed-value field, and forwards the downstream PPPOE data packet through an egress port of the matching ARP entry.