In this post , we cover basic overview of concepts involved in Radware App director load balancer and sample steps involved in creating a web farm for traffic load balancing.
Stand-Alone device
In simple terms,
- Consider there are 2 Web application servers of IP range 10.10.10.x range , to which web traffic from clients needs to be distributed in round robin method
- An Interface IP is first defined on the physical interface. If say client IP range is 20.20.20.x , then an IP of this range to one of the interfaces and the server IP range 10.10.10.x is assigned to the other interface. Once this is done static connected routes will be added automatically for traffic routing.
- A farm (group) is created with the 2 application servers and a CNAT IP of the app server 10.10.10.x range is assigned. (Note , NAT is required as IP ranges are different and there is no direct network access to either networks )
- Clients communicate with the device on a Virtual IP and all web traffic is directed to this IP. The concept of virtual IP here is more applicable when redundancy is used and client just need to communicate with a single IP and app director manages to balance the traffic across multiple boxes.
- App director in turn does a internal source IP NAT and forwards to the app servers and vice versa.
Redundancy - Active Backup
- The setup for redundancy is kept simple , the only difference being a VRRP is used between the interface IPs . Its very important to note this VRRP is used only between the app director devices to decide which box should be the Master and when should be the Backup.
- A VRRP is assigned for each interface IP and this should be of the client network IP range
4 simple steps involved in creating a simple farm for Web HTTP traffic distribution / load balancing.
a) Create Farm . Set the load balancing mode and dispatch / distribution method
b) Assign a client NAT IP to the farm using the Extended Farm Parameters
c) Create a L4 policy and assign a Virtual IP
d) Create the server table with the required servers to which the traffic is to be distributed and map it to the farm.
From Web interface select the option AppDirector - Farms - Farm Table
a) Create Farm . Set the load balancing mode and dispatch / distribution method
b) Assign a client NAT IP to the farm using the Extended Farm Parameters
c) Create a L4 policy and assign a Virtual IP
d) Create the server table with the required servers to which the traffic is to be distributed and map it to the farm.
Above steps should be sufficient to get your load balancing working. From client server push traffic onto the Virtual IP and port configured in L4 policy and verify on application servers traffic is distributed as per the Dispatch method.
Hope this helps to some geeks who are new to Radware app director load balancing concepts.