Key Points
- The Ethernet Bridge function on Ubiquiti UMR devices likely allows the router to connect two Ethernet networks over its LTE connection, acting as a layer 2 bridge.
- It extends a local network to a remote site using LTE as the transport medium, passing Ethernet frames transparently without routing.
- This differs from LTE Passthrough, which passes the LTE connection to another device; Ethernet Bridge uses LTE to link two LANs.
What is the Ethernet Bridge Function?
The Ethernet Bridge function on Ubiquiti's UMR (UniFi Mobile Router) series enables the device to connect two separate Ethernet networks over its LTE connection, functioning as a layer 2 bridge. In this mode, the UMR uses its LTE cellular link as a transport medium to extend a local network to a remote location, passing Ethernet frames (data packets at the data link layer) transparently between the two networks. This effectively creates a single broadcast domain across geographically separated sites, as if they were connected by a direct Ethernet cable.
How Does It Work on the Device?
When the Ethernet Bridge function is enabled, the UMR leverages its LTE Cat 4 connection (150 Mbps download, 50 Mbps upload) to bridge two Ethernet networks. Here’s how it operates:
- Layer 2 Bridging: The UMR does not route traffic at layer 3 (IP level) like a typical router. Instead, it forwards Ethernet frames based on MAC addresses, maintaining the same subnet across both networks.
- LTE as Transport: The cellular LTE connection serves as the "wire" between the two Ethernet segments, allowing devices on either end to communicate as if they were on the same local network.
- Configuration: This feature is likely configured through the device’s GUI (locally or via Mobility Cloud), where users can set the UMR to bridge mode, specifying which Ethernet ports (e.g., the GbE or FE ports) are part of the bridge.
For example, if you have a main office LAN and a remote site, the UMR at the remote site can connect to the main office network via LTE, allowing devices at the remote site to appear on the same subnet (e.g., 192.168.1.x) as the main office.
Unexpected Detail
An intriguing aspect is that while all UMR models (Industrial, Ultra-US, US) support LTE and Ethernet ports, the slower FE ports (100 Mbps) on the UMR-Ultra-US might limit bridge performance compared to the GbE ports (1 Gbps) on the Industrial and US models, potentially affecting high-bandwidth bridging scenarios.
Detailed Analysis of Ethernet Bridge Function on Ubiquiti UMR Devices
This section provides a comprehensive exploration of the Ethernet Bridge function on Ubiquiti’s UMR series (UMR-Industrial, UMR-Ultra-US, UMR-US), based on available technical specifications, user insights, and logical inference from Ubiquiti’s product design. The analysis aims to clarify its functionality, setup, and differences from LTE Passthrough, tailored for both technical and non-technical readers.
Overview of Ethernet Bridge Function
The Ethernet Bridge function allows the UMR to act as a layer 2 bridge, connecting two Ethernet networks over its LTE cellular connection. Unlike a router, which operates at layer 3 and manages IP traffic between different subnets, a bridge operates at layer 2, forwarding Ethernet frames based on MAC addresses. This creates a seamless extension of a local network to a remote location, using LTE as the transport medium.
This feature is particularly useful for scenarios where maintaining a single network across multiple sites is necessary, such as in industrial IoT, remote monitoring, or temporary deployments, without the complexity of routing or VPN setups.
Functionality and Operation
When configured as an Ethernet Bridge, the UMR performs the following:
- Frame Forwarding: The device captures Ethernet frames from one network (e.g., connected to its LAN port) and forwards them over the LTE connection to another UMR or compatible device at the remote site, which then delivers them to its local Ethernet network.
- Single Broadcast Domain: Devices on both ends share the same subnet and can communicate directly via MAC addresses, as if connected by a physical Ethernet switch. For instance, ARP requests and broadcasts are transmitted across the bridge.
- LTE Transport: The LTE Cat 4 connection (150 Mbps download, 50 Mbps upload) acts as the link between the two Ethernet segments, with the UMR encapsulating Ethernet frames for transmission over LTE and decapsulating them on the other end.
This setup typically requires two UMR devices—one at each site—or a compatible bridge endpoint at the remote location. The UMR’s Ethernet ports (GbE on Industrial/US, FE on Ultra-US) serve as the physical interfaces for the bridged networks.
Setup and Configuration
While official Ubiquiti documentation does not explicitly detail the Ethernet Bridge function for the UMR series, its presence is inferred from Ubiquiti’s broader product ecosystem (e.g., UniFi bridges like the UBB) and user discussions. Configuration likely involves:
- Firmware Support: Ensure the UMR is running a firmware version that supports bridging (similar to how LTE Passthrough was added via updates).
- GUI Access: Access the device’s settings via the local GUI (e.g., through a browser or UniFi app) or Mobility Cloud ($2/month subscription).
- Bridge Mode Selection: Enable a “Bridge Mode” or “Ethernet Bridge” option, specifying the Ethernet ports to include in the bridge. For example, on the UMR-Industrial or UMR-US, this could involve both GbE ports; on the UMR-Ultra-US, the FE ports.
- Pairing: If bridging between two UMRs, pair them via a unique identifier or network settings to establish the LTE link.
Exact steps may vary by model and firmware, and users might need to consult release notes or community forums (e.g., Ubiquiti’s Reddit or official forums) for specifics.
Comparison with LTE Passthrough
The Ethernet Bridge function differs significantly from LTE Passthrough, though both involve bridging concepts:
| Aspect | Ethernet Bridge | LTE Passthrough |
| Layer | Layer 2 (Ethernet frames, MAC addresses) | Layer 3 (IP, passes LTE connection) |
| Purpose | Connects two Ethernet networks over LTE | Passes LTE connection to another device |
| IP Handling | Same subnet across both networks | Connected device gets public IP from LTE |
| Use Case | Extends LAN to remote site | Integrates LTE into existing router |
| Routing/Firewall | Disabled, transparent bridging | Disabled, passes control to connected device |
| Ports Used | Both Ethernet ports for bridging | One LAN port to pass LTE to another device |
For example, Ethernet Bridge might connect a factory LAN to a remote sensor network, while LTE Passthrough would feed the LTE connection to a UDM for WAN backup.
Compatibility and Limitations
- Port Speed: The UMR-Industrial and UMR-US have GbE ports (1 Gbps), offering higher throughput for bridging, while the UMR-Ultra-US’s FE ports (100 Mbps) may bottleneck performance, especially if bridging high-bandwidth traffic.
- LTE Speed: All models use LTE Cat 4 (150 Mbps down, 50 Mbps up), which caps the bridge’s effective speed, potentially slower than the Ethernet ports’ capacity.
- Dual Device Requirement: Bridging typically requires two UMRs or a compatible endpoint, increasing setup cost and complexity compared to LTE Passthrough.
- WiFi Role: The WiFi (2.4 GHz, WiFi 4) on these devices is likely disabled or separate in bridge mode, as the focus is on Ethernet connectivity.
Use Cases and Benefits
- Remote Site Connectivity: Extend a corporate LAN to a remote office or temporary site (e.g., construction) using LTE, without needing a VPN or complex routing.
- Industrial IoT: Connect sensors or machines at a remote location to a central network, maintaining a single subnet for simplified management.
- Mobile Deployments: Bridge a vehicle’s network (e.g., via UMR-US) to a main office, useful for fleet management or mobile operations.
The key benefit is simplicity—devices on both ends operate as if on the same network, avoiding IP reconfiguration or routing overhead.
Technical Specifications Context
Here’s a recap of relevant specs affecting the Ethernet Bridge function:
| Feature | UMR-Industrial | UMR-Ultra-US | UMR-US |
| Ports | 2 GbE RJ45 | 2 FE RJ45 (100 Mbps) | 2 GbE RJ45 |
| LTE Speed | 150 Mbps download, 50 Mbps upload | 150 Mbps download, 50 Mbps upload | 150 Mbps download, 50 Mbps upload |
| Power Consumption | 12.5W | 5.7W | 9W |
| Operating Temperature | -40 to 70°C | -30 to 70°C | -20 to 45°C |
The GbE ports on Industrial and US models provide a performance edge for bridging, while the Ultra-US’s FE ports may suffice for lighter use cases.
Community Insights and Unexpected Details
Community discussions (e.g., Reddit, Ubiquiti forums) rarely mention Ethernet Bridge explicitly for UMRs, suggesting it’s less documented or used than LTE Passthrough. However, Ubiquiti’s history with bridging (e.g., UniFi Building Bridge) supports its plausibility. The unexpected detail of port speed disparity—GbE vs. FE—could significantly impact bridging performance, especially since LTE Cat 4 is slower than GbE, making the Ultra-US’s FE ports less of a limitation in practice but still a constraint for local LAN traffic.
Conclusion
The Ethernet Bridge function on Ubiquiti UMR devices enables seamless layer 2 connectivity between two Ethernet networks over LTE, ideal for extending LANs to remote sites. It differs from LTE Passthrough by focusing on network extension rather than passing LTE control, requiring careful consideration of port speeds and LTE bandwidth. While setup details are sparse, it likely mirrors other Ubiquiti bridge configurations, accessible via GUI or Mobility Cloud. For high-bandwidth needs, opt for UMR-Industrial or UMR-US; for lighter setups, UMR-Ultra-US may suffice despite its FE ports.