Network Settings - Multi-WAN

Overview

The multi-WAN feature in ClarkConnect allows you to connect your system to multiple Internet connections. ClarkConnect multi-WAN not only provides load balancing, but also automatic failover.

Installation

If you did not select this module to be included during the installation process, you must first install the module.

How It Works

ClarkConnect multi-WAN has the following features:

• auto-failover
• load balanced
• round-robin based on user-defined weights (see configuration section)

To give you an example of how multi-WAN works, imagine two 1 Mbit/s DSL lines with two users on the local network. With every new connection to a server on the Internet, the multi-WAN system alternates WAN interfaces. User A could be downloading a large file through WAN #1, while User B is making a voice-over-IP (VoIP) telephone call on WAN #2.

With some applications, the download speed for the multi-WAN system can use the full 2 Mbit/s available. For example, downloading a large file from a peer-to-peer network will use the bandwidth from both WAN connections simultaneously. This is possible since the peer-to-peer technology uses many different Internet "peers" for downloading. At the other end of the spectrum, consider the case of downloading a large file from a web site. In this case, only a single WAN connection is used -- 1 Mbit/s maximum.

Bandwidth aggregation (combining multiple WAN interfaces to look like a single WAN interface) is not possible without help for your ISP since both ends of an Internet connection must be configured.

Configuration

Enable/Disable

When multi-WAN is enabled, all active WAN interfaces are used to connect to the Internet. When multi-WAN is disabled, the first active WAN interface is the only network used to connect to the Internet.

Weights

Multi-WAN weights are used to load balance outbound Internet traffic. By default, all WAN interfaces are given a weight of one. This default configuration means the network traffic will be (roughly) evenly split amongst the different WAN connections.

In one of the typical multi-WAN configurations, a second broadband connection is used for backup. This second connection is often a low-cost and low-bandwidth connection. In this case, you would want to set the weight on your high-bandwidth connection to 3 or 4, while leaving your low-cost/low-end connection with a weight of 1.

Source Based Routes

In some situations, you may want a system on your local area network (LAN) to always use a particular WAN interface. The screenshot below displays the configuration for two scenarios:

• Sending network traffic for the 216.138.245.16/28 block of Internet IPs out the eth0 WAN.
• Sending network traffic from a voice-over-IP (VoIP) server on the LAN at 192.168.1.100 out the eth1 WAN.

Destination Port Rules

In some situations, you may want to send network traffic for a specific port from your LAN out a particular WAN interface. The screenshot below displays the configuration for always sending DNS traffic (port 53) out the eth0 WAN network.

	Warning!

Destination port rules only apply to connections originating on your LAN. These rules do not apply to traffic originating from the ClarkConnect system itself

Routing Policies

Some Internet service providers (ISPs) will not allow traffic from source addresses they do not recognize as their own. The following scenarios will give you a good idea of common issues faced in a multi-WAN environment. In the examples, we assume two connections, but the same issues crop up with three or more connections.

DNS Servers

The DNS servers configured on the ClarkConnect system will be provided by one or both ISPs. In our example, we are going to assume that ISP #1 provides the DNS servers. If a DNS request from your network goes out the ISP #2 connection, it might get blocked by ISP #1. Result: DNS requests will only succeed on ISP #1.

Solution -- Use DNS servers that are accessible from any network. If your ISPs do not provide such DNS servers, then we recommend using OpenDNS.

Note: your DHCP/DSL network configuration settings should have the Automatic DNS Servers checkbox unchecked - see screenshot.

DMZ Networks and 1-to-1 NAT

If you have a range of extra IP addresses provided by ISP #1, you may need to explicitly send traffic from these extra IPs out the ISP #1 connection. ISP #2 may drop the packets.

Solution -- Use a Source Based Route for your DMZ network.

Links

• Linux Advanced Routing and Traffic Control