Loadbalancer.org glossary
Least connection / weighted least connection
What is the Least Connection method?
With this load balancing algorithm, incoming requests are distributed to Real Servers with the fewest connections relative to each Real Server’s weight.
Servers with a higher weight receive more requests. A server with a weight of 200 will receive 4 times the number of requests than a server with a weight of 50. Weightings are relative, so it makes no difference if Real Server #1 and #2 have weightings of 50 and 100 respectively or 5 and 10. This is the default method for new VIPs.