6.4 Network Load Balancing
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## 6.4 Network Load Balancing

If at least two Internet links are available, WinRoute can divide traffic in parts sent by either of them. The benefits of such solution are evident — Internet connection throughput gets better (i.e. speed of data transmission between the LAN and the Internet increases) and response time gets shorter for connections to servers in the Internet. If special traffic policy is not defined (so called policy routing — see chapter 7.5 Policy routing), then individual links are also backed-up mutually (see also chapter 6.3 Connection Failover) — in case of failure of one of the lines, the traffic is routed via another.

Note:

1. Network load balancing is applied only to outbound traffic via the default route. If the routing table (see chapter 18.1 Routing table) defines a route to a destination network, traffic to the network will always be routed through the particular interface.

2. Network load balancing does not apply to the traffic of the firewall itself. This traffic is processed directly by the operating system and, therefore, the standard routing is applied here (the default route with the lowest metric value will always be used).

### Requirements

The computer hosting WinRoute must have two network interfaces for connection to the Internet, i.e. leased (Ethernet, WiFi) or persistently connected dial-up links (CDMA, PPPoE). Usual dial-ups (analog modem, ISDN) are not suitable, because it is not possible to dial on demand in the network load balancing mode.

This connection type also requires one or more network cards for connection of individual segments of the LAN. Default gateway must NOT be set on any of these cards (cards for the LAN)!

In case of dial-ups (CDMA, PPPoE), it is also necessary to define corresponding telephone connection in the operating system. It is not necessary that login data for telephone connections are saved in the system, this information can be specified directly in WinRoute.

Both the primary and the secondary link may be configured automatically by the DHCP protocol. In that case, WinRoute looks all required parameters up in the operating system.

It is recommended to check functionality of individual Internet links out before installing WinRoute. The following testing methods can be applied (to both links):

- If these links are two dial-ups, connect one after the other and check access to the Internet.

- If one link is leased and the other a dial-up, test the leased link connection first and then dial the other one. Dialing of the link opens (creates) a new default route via this link which allows us to test Internet connection on the secondary link.

- In case of two leased links, the simplest way is to disable one of the connections int he operating system and test the other (enabled) link. And, as implied, test the other in the same way when the first link is checked.

This method can be applied to any number of Internet lines.

### Configuration with the wizard

On the second page of the Traffic Policy Wizard (see chapter 7.1 Network Rules Wizard), select Multiple Internet Links — Traffic Load Balancing.

Figure 6.13. Network Policy Wizard — network load balancing

On the third page of the wizard, add all links (one by one) which you intend to use for traffic load balancing.

Figure 6.14. Traffic Policy Wizard — failover of a leased link by a dial-up

For each link, specification of bandwidth is required (i.e. traffic speed). The absolute value of the link speed is not important (however, just for reference reasons, it should correspond with the link speed suggested by the ISP). The important aspect is the ratio of speed between individual links — it determines how Internet traffic will be divided among these links.

If login data for the selected telephone connections are not saved in the operating system, valid username and password are required.

### Example

Let us suppose there are two Internet links available. You set their bandwidth values to 4 Mbit/s and 8 Mbit/s. Total (proposed) speed of the Internet connection is therefore 12 Mbit/s, while one link provides one third of this capacity and the other link provides two thirds. Simply said, one third of overall Internet traffic will be routed through one link and the resting two thirds through the other one.

### Resulting interface configuration

When you finish set-up in Traffic Policy Wizard, the resulting configuration can be viewed under Configuration → Interfaces and edited if desirable.

Figure 6.15. Configuration of interfaces — network traffic load balancing

The Internet interfaces group includes the Internet 4Mbit and the Internet 8Mbit link selected as an interface for Internet traffic load balancing on the third page of the wizard.

The Internet column shows proposed speed of individual links (see above). The Status column informs of the current status of the link (up/down) as well as of the fact whether the link is active, i.e. whether connection on this Internet link is working and part of Internet traffic can be routed through it.

Other interfaces (including Dial-In) are considered as segments of the LAN and put in Trusted / Local interfaces.

For any new link added to the Internet interfaces group, the default speed of 1 Mbit/s will be set. Then it is possible and also recommended to edit the proposed link speed in the interface settings (see chapter 5 Network interfaces) with respect to its real speed, which makes the balancing efficient and working smoothly.

### Hint

Speed of one or more links can be set even for 0 Mbit/s. Such links will then not be used for network traffic load balancing, but for traffic routing in accordance with specific traffic rules (see chapter 7.5 Policy routing). However, availability of these links will still be tested and the links will serve as alternative for case that all the other links fail.

### Advanced settings (optimization, dedicated links, etc.)

In basic configuration, network load balancing is applied automatically with respect to their proposed speeds (see above). It is possible to use traffic rules to modify this algorithm (e.g. by dedicating one link for a particular traffic). This issue is described in detail in chapter 7.5 Policy routing.

### Probe hosts

Functionality of individual Internet links is regularly tested by sending an ICMP request for a response (PING) to certain hosts or network interfaces. By default, the default gateway of the particular link is used as the probe host. If the default gateway is not available, the tested link is not working (correctly).

If the primary default gateway (i.e. the default gateway set for the tested link) cannot be used as the testing computer by any reason, it is possible to specify IP addresses of other (one or more) testing computers upon clicking on Advanced. If at least one of the tested devices is available, the Internet connection in question is considered as functioning.

The specified probe hosts will be used for testing of availability of all Internet links. Therefore, the group of testing computers should include a few hosts belonging to various subnets of the Internet.

Figure 6.16. Network load balancing — setting probe hosts

Note:

1. Probe hosts must not block ICMP Echo Requests (PING) since such requests are used to test availability of these hosts — otherwise the hosts will be always considered as unavailable. This is one of the cases where the default gateway cannot be used as the testing computer.

2. Probe hosts must be represented by computers or network devices which are permanently running (servers, routers, etc.). Workstations which are running only a few hours per day are irrelevant as probe hosts.

3. ICMP queries sent to probe hosts cannot be blocked by the firewall's traffic rules.

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