Linux Virtual Server

Linux Virtual Server (LVS) is load balancing software. It is for Linux kernel–based operating systems.
LVS is a free and open-source project. It has started by Wensong Zhang in May 1998. It is subjected to the requirements of the GNU General Public License (GPL), version 2. 
The mission of the project is to build a high-performance and highly available server for Linux using clustering technology, that provides good scalability, reliability and serviceability.
Glossary.
Commonly used terms include the following:
Examples.
Setting up a virtual HTTP server with two real servers:
ipvsadm -A -t 192.168.0.1:80 -s rr
ipvsadm -a -t 192.168.0.1:80 -r 172.16.0.1:80 -m
ipvsadm -a -t 192.168.0.1:80 -r 172.16.0.2:80 -m
The first command assigns TCP port 80 on IP address 192.168.0.1 to the virtual server. The chosen scheduling algorithm for load balancing is round-robin (codice_1). The second and third commands are adding IP addresses of real servers to the LVS setup. The forwarded network packets shall be masked (codice_2).
Querying the status of the above configured LVS setup:
IP Virtual Server version 1.0.8 (size=65536)
Prot LocalAddress:Port Scheduler Flags
 -&gt; RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 192.168.0.1:80 rr
 -&gt; 172.16.0.2:80 Masq 1 3 1
 -&gt; 172.16.0.1:80 Masq 1 4 0