WAN Failover Configuration for Edgewater EdgeMarc Series
Overview
Integrating cellular Internet access into a traditional, wireline data network is typically accomplished through one of three interfaces: USB aircards, embedded radios, or a dedicated cellular networking appliance. Of these methods, only the dedicated appliance provides a solution that can overcome the challenges of deploying reliable LTE connectivity.
Both USB aircards and embedded radios only capture cell signals as they are received from the equipment closet or server rack where the edge appliance resides (since both must integrate directly in/ on a host device). This is rarely where coverage is optimal. Aircards in particular present significant challenges due to their need for driver support, their lack of external antennas, and the short lifespan of these consumer-grade dongles.
LTE networking appliances are ideal for wireless WAN failover because they integrate with networks via Ethernet (or WiFi). To streamline cellular deployments, Digi's Cellular Extenders are optimized from the point of installation all the way through to data plan management. Setup is simplified when using a Remote Mounting Kit (RMK) -- the included (passive) PoE injector and temporary battery pack for site survey -- and Digi Cellular Extenders are set for IP passthrough by default to ensure the backup (cellular) WAN connection is completely controlled by the network's existing edge.
This document covers how to install a Digi Cellular Extender and configure it for failover with a third-party networking appliance. Since all Digi Cellular Extenders, the 6300-CX and 6310-DX, default to IP passthrough, most of the software settings described below apply to the third-party device referenced in this article. Requirements for dual-WAN configuration will vary depending on the make and firmware version of the edge appliance controlling the failover parameters.
Interoperability Matrix
This section covers interoperability information of the hardware tested for this solution. It includes the firmware versions of both devices as well as the date of testing.
| Date | VOS Release | 6300-CX Firmware |
|---|---|---|
| 10/2016 |
14.1 |
16.3.15 |
Caveats
Good signal strength is required to maintain reliable cellular Internet access. A site survey should be performed prior to installing the Digi Cellular Extender. While network performance varies depending on the carrier and location, all deployments can be optimized to minimize the challenges presented by building materials, RF interferene, and other environmental constraints.
Using a Digi Celluler Extender for WAN failover assumes that an active Internet connection is available from another network interface set as the primary connection for the edge appliance. It is recommended that the Cellular Extender runs in IP passthrough mode to integrate seamlessly with existing IT infrastructure.
NOTE: The third-party appliance tested in this document was running its default configuration. If the steps outlined in this document interfere with existing customizations, or vice versa, consider backing up the edge appliance's current settings and testing failover functionality after temporarily erasing the third-party device's configuration.
Digi Cellular Extender Setup
Initial Setup
Digi Cellular Extenders have a socket that houses the CORE 1002-CM Plug-In Modem in order to provide LTE connectivity. Prior to plugging in the modem, insert an active 2FF SIM card into either (or both) of the 1002-CM's two SIM slots.
After securing the plug-in module, cover the exposed side of the main appliance using the included faceplate and affix both antennas. The unit is now assembled for cellular network access.
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Site Survey
The mounting bracket that comes with Digi Cellular Extenders presents multiple options for device placement. Perform a site survey to make an informed decision as to where the ideal on-site location for cellular services might be, based off of reception and proximity to the edge appliance.
Using the temporary battery pack, power up the unit and wait for it to establish a cellular connection before moving around to potential install locations -- see the LEDs section of this document for more information on the Digi Cellular Extender's various status indicators.
NOTE: If the Cellular Extender is having difficulties connecting to its LTE network, please refer to the article that covers Staging for Initial Connectivity.
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Power Option 1: Remote Installation
Digi offers a Remote Mounting Kit (RMK) that includes 3 key components:
- Passive Power-over-Ethernet (PoE) Injector
- Temporary Battery Pack
- Install Accessories
Using the PoE injector, the Digi Cellular Extender can be powered up to 300 ft away from the unit's power supply using only the (Cat 5 or Cat 6) Ethernet cable that also integrates LTE data access into the network.
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Power Option 2: Direct Installation
If optimal signal is readily available within range of a power outlet, Digi's Cellular Extenders can be connected directly to the included power supply and then integrated into the network using a standard Ethernet cable.
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LEDs
Once power has been established, the Digi Cellular Extender will initialize and attempt to connect to a cellular network per the settings provisioned to its inserted SIM card. Device initialization may take several minutes as it joins an LTE network for the first time.
Indicator lights on the Wireless Strength Indicator update every 30 seconds to show the currently observed signal strength, while the Network Status Light updates to display the type of cellular connectivity available. Please refer to the following table for more information:
IP Passthrough
Digi Cellular Extenders are set by default with IP passthrough configured for the PoE-enabled Ethernet port, meaning any client device connected to the passthrough interface will receive the IP address directly assigned to the Cellular Extender's LTE radio.
It is suggested that IP passthrough is used when deploying a backup WAN connection into an edge appliance to ensure seamless network integration. With passthrough enabled the Cellular Extender will not directly control the routing of packets going to or from its LTE radio interface, instead deferring to the logic (routing tables and firewall policies) of the edge appliance.
To toggle IP passthrough on or off, please refer to the following configuration example: LAN port with IP passthrough. Note that this is only required for devices running non-standard configs.
EdgeMarc Configuration
WWAN as the Primary Interface
The back panel of the EdgeMarc ESBC features an array of LAN ports and two dedicated WAN interfaces. To utilize a Digi Cellular Extender's LTE wireless WAN (WWAN) connectivity as the primary means of Internet access, connect the Digi device to port WAN 1 on the EdgeMarc device using an Ethernet cable. A solid blue light on the cellular extender's LTE indicator confirms that its 4G LTE modem is online and an Ethernet connection has been established with another device.
Access the Edgewater admin portal at 192.168.1.1
Please refer to the EdgeMarc VOS User Guide for an in-depth walkthrough of the device’s local GUI.
NOTE: The Static IP radio button is selected by default.
NOTE: A message will indicate that service will be temporarily interrupted as the new settings are established. |
WAN Link Redundancy (WLR) with WWAN Failover
The WAN Failover menu initializes WLR and further configures the interaction between primary and secondary WANs. Even with both WAN ports connected to an active Internet connection, the EdgeMarc ESBC is unable to utilize the secondary uplink until WAN Link Redundancy is enabled by selecting the corresponding check box. Additional settings may be engaged once the WLR status is updated.
Please refer to the EdgeMarc VOS User Guide for an in-depth walkthrough of the device’s local GUI.
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