The link load balancer uses pools to increase your available bandwidth, maximize throughput, and add redundancy. It combines the capacity of multiple external connections and balances the data requests across them proportionately. This is not the same as adding bandwidth shaping policies to mange traffic from applications, see our help topic, About shaping policies. You can only apply this to external connections. It works with traffic generated from services running on the Smoothwall Filter and Firewall itself, such as the Smoothwall Filter or Email relay and supports all external connection types, including dynamic DHCP and PPPoE.
This does not support Bonding whereby multiple connections are presented as one. Bonding requires special equipment at both ends of the connection. However, your ISP might provide this.
Failover
Failover is when one connection goes down, another connection is assigned to take its place. As soon as those failed connections come back online, the Failback reinstates them automatically. You can also set up Failover rules for each pool independently.
If you set the bandwidth values of your external connections incorrectly, their ratios are generated based on those incorrect figures. The Smoothwall Firewall always maximizes the use of any active connection, so they don't limit their available bandwidth, but the distribution of data won't be optimal. Incorrect values also hinder management because they aren’t an accurate representation of available resources.
If your Internet connection prevents our Connection monitoring function from reaching Google’s DNS, you must turn off monitoring. This keeps a connection’s status as "up" even if it is not connected. This means that any data sent down this connection is dropped if the connection is down.
Link load balancing pools
A pool is a group of external connections, and each pool has its own rules and ratios for failover and dividing bandwidth. An LLB pool identifies the level of bandwidth needed to avoid creating a bottleneck. You allocate those interfaces that you need to fulfill the targeted bandwidth to the pool. The total bandwidth from all allocated interfaces can be more than the targeted bandwidth to allow for high availability.
The Smoothwall Filter and Firewall balances the traffic load according to the number of interfaces assigned, and the bandwidth allocated and available on each interface. For example, a pool with two interfaces assigned, where one interface has twice the allocated bandwidth, balances the traffic using a 2:1 weighting ratio.
Connections must be listed in the order they're to be applied, so that if the first connection isn't equal to or greater than the target bandwidth, the next connection is also used to fulfill the pool’s targeted bandwidth, even if that results in exceeding the target.
Provided pools
If you have you have upgraded your Smoothwall Filter and Firewall from an earlier version, you might have some load balancing pools already configured. These use the maximum available bandwidth for that interface. However, you can change this to suit your organizational needs.
- Forwarded: For load balanced outgoing traffic
- Migrated primaries: For load balanced traffic, originating from the previous primary interface, or interfaces.
- Web filter: For load balanced, traffic that uses a proxy server. This pool is only created if you install the Smoothwall Filter.
Note: New installations of the Smoothwall Filter and Firewall don't have predefined pools. You can create load balancing pools to suit your organizational needs.
Example link load balancing configuration
Two link load balancing pools with the interfaces as follows:
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Sales Office - 5-Mbps:
This pool only needs 5-Mbps to be able to meet all devices’ bandwidth needs. This pool can use these three connections to fulfill this. Link 1 provides the bandwidth needed, the other two are only used if the first link fails. Link 3 is only used if Link 1 and Link 2 are unavailable.
Local Address | Bandwidth |
MyTelecom Link 1 (1.0.1.0/24) | 5-Mbps |
MyTelecom Link 2 (1.0.1.1/24) | 5-Mbps |
MyTelecom Link 3 (1.0.1.2/24) | 10-Mbps |
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Research Office - Use maximum bandwidth:
This pool can use the maximum available bandwidth. Therefore, the Smoothwall Filter and Firewall uses both connections for traffic, but balances the load using a 2:1 weighting ratio because Link 4 has double the allocated bandwidth than Link 3.
Local Address | Bandwidth |
MyTelecom Link 3 (1.0.1.2/24) | 10-Mbps |
MyTelecom Link 4 (1.0.1.3/24) | 20-Mbps |
Link 3 can be used by both pools. If Link 3 is used by both pools, traffic is balanced as follows:
- All traffic from the Sales Office pool.
- 1/3 of traffic from the Research Office pool weighting of 2:1 is still maintained for this pool, even if other pools are using the same link as available bandwidth, and link saturation isn't measured.