The evolution of Elastic Load Balancing (ELB) has responded to need for the automatic adjustment of capacity based upon the volume of incoming application traffic and the load balancers increase or decrease their capacity to deal with the variable volume of access requests being made.
Elastic load balancing is one of the best ways for cloud computing operators to provide affordable scalability to satisfy their SLAs that they have made with their customers. Traditional network load balancing consists of load balancers sharing work among the network servers based on server response times. Sometimes an even more basic “Round Robin” approach is used where the load balancer directs traffic to each network server on a preprogrammed sequence and will only stop directing traffic to a particular server if the server fails to respond.
ELB solutions are far more sophisticated and offer cloud-computing operators scalable capacity based on traffic requirements at any one time. Kemp Technologies Application Delivery Controllers or ADCs offer many of the facilities required for elastic load balancing in the hardware appliances these include
- Layer 4 and Layer 7 heath checking
- Directing traffic only to servers and applications that respond correctly to these health checks
- Centralized management of SSL certificates
- Ability to authenticate public keys
- Full support of both IP4 and IP6
Once we turn our focus to the Kemp Virtual LoadMasters (VLM) a whole new series of elastic load balancing options become available. Firstly, fault tolerance becomes a reality by allowing the cloud-computing operator to deploy a range of virtual ADCs that can be set to adjust their resource capacity based upon user traffic and incoming throughput demands. ELB can be set up to serve users from a single location or even across multiple physical locations even in different countries, by doing this, the risk of a single point of failure is taken away and the ability to handle traffic consistently is maintained.
The Cisco UCS Loadmaster is perhaps the most elastic iteration of the Kemp Technologies ELB solution because the VLM addresses its needs directly to the hardware without having to pass through the operating system (VMware, Hyper V, XEN, and KVM). While the Hypervisor can “police” the VLM to avoid performance problems, it can cause potential bottlenecks caused by having to run the VLM over an operating system rather than directly addressing its load balancing to the hardware itself. As the Cisco UCS Loadmaster is a fully certified solution, the user can be confident that it will work perfectly.