How To Configure Load Balancer Redundancy on Allied Telesis Routers and Switches
Introduction
In many Server Hosting environments, two requirements are important: maximising throughput availability to each service, and minimising service downtime. This How To Note contributes towards both these aims.
The Note is split into two parts. The first part illustrates both redundancy of servers and redundancy of the load balancers themselves. The second part provides an optional extension that enables you to control server selection without losing redundancy. This is helpful when you prefer to have customers access a certain server, instead of balancing that traffic. However, if that server fails, the customers need to use the alternate server instead.
The examples
The network configuration for these examples is shown in the following figure.
public side | Load Balancer 1 |
| private side | |
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| public address | private address |
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| 172.214.1.3 | 192.168.1.200 |
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| redundancy |
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| management |
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| VLAN 4 | private |
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| 192.168.2.2 | Web/SFTP server 1 | |
| redundant |
| VLAN 3 | |
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| 192.168.1.1 | ||
public | load balancer |
| with VRRP | |
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VLAN 2 | virtual address |
| virtual |
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| 172.214.1.2 |
| address |
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| redundancy | 192.168.1.202 | |
client |
| management |
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| VLAN 4 |
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| 192.168.2.1 |
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| public address | private address |
| Web/SFTP server 2 |
| 172.214.1.4 | 192.168.1.201 |
| 192.168.1.2 |
| Load Balancer 2 |
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The Note’s first example illustrates how to load balance web services, and includes:
•Load balancing of incoming web traffic to maximise throughput to web servers. It also provides redundancy if a web server goes down.
•Redundancy between two load balancing routers. In the unlikely event of a router going down, a backup router takes over as master and continues the load balancing work for incoming web connections. Load balancer redundancy and VRRP ensure that clients and servers access the same public and private addresses no matter which router is the master.
•A firewall to secure the LAN against attack. The firewall configuration changes automatically if the backup router takes over the load balancing role.
www.alliedtelesis.com |