Positron G.hn Media Converters

Positron Access Solutions provides G.hn (Gigabit Home Networking) media converter systems that deliver high-speed Ethernet connectivity over existing copper infrastructure (twisted pair, coaxial cable, or powerline). The rXg integrates with Positron GAM (G.hn Access Multiplexer) systems for automated subscriber provisioning, VLAN management, and bandwidth profile assignment.

Overview

G.hn technology enables multi-gigabit networking over legacy copper wiring, making it ideal for: - MDU (Multi-Dwelling Unit) deployments - Hospitality environments - Office buildings with existing copper infrastructure - Brownfield deployments where fiber installation is impractical

Supported Models

Architecture

The Positron system uses a three-tier architecture:

1. GAM (G.hn Access Multiplexer): Central aggregation device managed by rXg
2. Endpoints: Physical G.hn devices at subscriber locations
3. Users/Subscribers: Logical entities representing subscriber configurations

Endpoint and Subscriber Model

The Positron client manages two distinct concepts:

• Endpoints: Physical devices identified by MAC address. These are automatically discovered when G.hn devices connect to the GAM.
• Users (Subscribers): Logical configurations applied to endpoints, containing VLAN assignments, bandwidth profiles, and other settings.

When a new endpoint is detected, the rXg can automatically create a corresponding subscriber configuration based on associated Account or MediaConverter settings.

Features Supported

Prerequisites

Firmware Requirements

Network Requirements

• Management IP connectivity from rXg to GAM
• HTTP API access (TCP port 80) for JSON-RPC
• SNMP access (UDP port 161) for monitoring
• Layer 2 connectivity for VLAN trunking to GAM uplink

Onboarding Process

GAM Initial Configuration

The GAM device requires basic network configuration before rXg integration:

1. Configure management IP address on GAM
2. Enable JSON-RPC API access
3. Configure SNMP community
4. Connect GAM uplink port to rXg-managed infrastructure
5. Add GAM as Infrastructure Device in rXg

Adding GAM to rXg

When adding a Positron GAM to rXg Infrastructure Devices:

Endpoint Provisioning

Endpoints (subscriber G.hn devices) are provisioned through MediaConverter records in rXg:

1. Create a MediaConverter record for each endpoint
2. Associate the MediaConverter with the GAM's PON/G.hn port (Switch Port)
3. Assign VLAN configuration via Switch Port Profile or direct VLAN assignment
4. Associate with an Account for billing integration (optional)
5. Config sync will automatically create the endpoint and subscriber on the GAM

Configuration

Connection Settings

The rXg connects to Positron GAM devices via JSON-RPC API over HTTP.

API endpoint: http://<host>/cgi/json-rpc

Request format: json { "method": "<api_method>", "id": "<request_id>", "jsonrpc": "2.0", "params": { ... } }

API Methods

The Positron client uses the following JSON-RPC methods:

VLAN Configuration

Single VLAN Assignment

For simple deployments, assign a single VLAN to each subscriber port:

• Configure the Native VLAN on the MediaConverter's Switch Port Profile
• Config sync will configure the port as an untagged member of that VLAN

QinQ Double Tagging

For service provider deployments requiring double VLAN tagging:

Inner Tag (C-VLAN) : Customer VLAN, typically unique per subscriber
Outer Tag (S-VLAN) : Service VLAN, typically shared across the GAM

QinQ configuration is derived from: - Inner tag: From Account's VLAN assignment or Switch Port Profile - Outer tag: From second port VLAN configuration on the Switch Port

Management Port

Port Gi 1/1 is reserved as the management port on GAM devices and is not available for subscriber configuration.

Bandwidth Profiles

Bandwidth profiles are applied to subscribers based on associated Account settings:

1. Account has an associated Usage Plan
2. Usage Plan defines rate limits
3. Config sync creates or assigns bandwidth profiles on the GAM
4. Bandwidth profiles are applied per-subscriber

Bandwidth profile parameters: - Maximum upstream rate (bps) - Maximum downstream rate (bps)

Firmware Upgrade

The rXg can trigger firmware upgrades for G.hn endpoints:

1. Upload firmware file to appropriate location
2. Trigger upgrade via API
3. GAM pushes firmware to connected endpoints
4. Endpoints reboot with new firmware

Monitoring Capabilities

Data Gathered

The config sync process gathers the following data from the GAM:

• Endpoints: List of all endpoints with MAC addresses
• Users/Subscribers: Current subscriber configurations
• Ports: Port configurations including VLANs
• VLAN Data: Current VLAN assignments (tagged/untagged)

Troubleshooting

Common Issues

Endpoint Not Appearing

Symptom: New G.hn device not showing in GAM Resolution: - Verify physical connectivity (coax/twisted pair connection) - Check G.hn link LED on endpoint - Verify endpoint is powered on - Check GAM port status via API or web interface

Subscriber Configuration Not Applied

Symptom: Config sync runs but subscriber settings not updated Resolution: - Verify MediaConverter MAC address matches endpoint MAC - Check MediaConverter is associated with correct Switch Port - Verify VLAN configuration on Switch Port Profile - Check API connectivity to GAM - Review config sync logs for errors

QinQ Not Working

Symptom: Double-tagged traffic not forwarding correctly Resolution: - Verify upstream switch supports QinQ - Check outer VLAN is configured on upstream trunk - Verify inner/outer tag values are correct - Check GAM uplink port VLAN configuration

API Connection Failures

Symptom: Unable to communicate with GAM API Resolution: - Verify GAM management IP is reachable - Check HTTP (port 80) connectivity - Verify API credentials are correct - Check GAM web interface is accessible

Diagnostic Information

Endpoint list from API: json { "method": "ghnAgent.config.endpoint.get", "params": {} }

User/subscriber list: json { "method": "ghnAgent.config.user.get", "params": {} }

Port configuration: json { "method": "ghnAgent.config.port.get", "params": {} }

Known Limitations

• Management Port Reserved: Port Gi 1/1 cannot be used for subscriber traffic
• No 802.1X: G.hn technology does not support 802.1X authentication
• MAC-Based Identification: Endpoints are identified by MAC address only
• API-Only Management: No SSH/CLI access; all management via JSON-RPC API
• Single GAM per Infrastructure Device: Each GAM requires its own Infrastructure Device record

Operational Caveats

• Endpoint Discovery Timing: New endpoints may take several minutes to appear in the GAM after physical connection
• Configuration Apply: Changes are staged and must be applied via apply_config API call
• Bandwidth Profile Creation: If a required bandwidth profile doesn't exist, config sync will create it automatically
• Endpoint-User Binding: Each endpoint can only have one active user/subscriber configuration
• VLAN Limits: Check GAM model specifications for maximum VLAN and subscriber counts
• G.hn Signal Quality: Performance depends on copper cable quality and distance

External References

• Positron Access Solutions
• G.hn Technology Overview
• ITU-T G.9960/G.9961 Standards