Open Source Load Balancer5498219

Zen Load Balancer is an  Open Source Load Balancer  Appliance Project that provides a full set of tools to run and manage a complete load balancer solution which includes: farm and server definition, networking, clustering, monitoring, secure certificates management, logs, config backups, etc.

2. BASIC CONCEPTS Farm is a set of servers that offer the same service over a single one entry point defined with an IP address and a port, which is commonly called virtual service. The main farm work is to deliver the client virtual service connection to the real backend service and back. Meanwhile, the farm definition establishes the delivery policies to every real server.

Backend is a server that offers the real service over a farm definition and it process all the real data requested by the client.

Client is called to the IP address that connects to the virtual service of the initial connection that usually a user requests. The client IP address that opens a new connection on the virtual service side is used to communicate with the user. The same client could generate several (layer 4) connections to the virtual service, and an IP client address could be generated by several users.

Application Session is a layer 7 concept which tries to identify the requests of a single user although several clients shares the same IP client address.

Real IP is a physical IP address over a layer 4 network configuration which is assigned to a server or NIC.

Virtual IP is a floating IP address over a layer 4 network configuration which is used to be the entry point of a virtual service defined by a farm that is ready to deliver connections between redundant load balancing nodes.

3. ZEN INSTALLATION

3.1 DOWNLOAD THE INSTALL ISO IMAGE The load balance appliance installer is able to be downloaded from the official website that could be used to:

Burn an installer CD-ROM to install under a physical machine Record on an USB device to install on a physical machine with usb boot support Install on a virtual machine through a virtualization software

One of the most common applications of load balancing is to provide a single Internet service from multiple servers, sometimes known as a server farm. Commonly, load-balanced systems include popular web sites, large Internet Relay Chat networks, high-bandwidth File Transfer Protocol sites, Network News Transfer Protocol (NNTP) servers and Domain Name System (DNS) servers. Lately, some load balancers evolved to support databases; these are called database load balancers.

For Internet services, the load balancer is usually a software program that is listening on the port where external clients connect to access services. The load balancer forwards requests to one of the "backend" servers, which usually replies to the load balancer. This allows the load balancer to reply to the client without the client ever knowing about the internal separation of functions. It also prevents clients from contacting backend servers directly, which may have security benefits by hiding the structure of the internal network and preventing attacks on the kernel's network stack or unrelated services running on other ports.

Some load balancers provide a mechanism for doing something special in the event that all backend servers are unavailable. This might include forwarding to a backup load balancer, or displaying a message regarding the outage. Load balancing gives the IT team a chance to achieve a significantly higher fault tolerance. It can automatically provide the amount of capacity needed to respond to any increase or decrease of application traffic

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