What's the difference between load balancing and failover?

Question

I am asking best practice/info/docs of how to have 2 apache web servers in load balancing.
- Which httpd module do I have to load in the http conf?
- I was reading that I have to have a web load balancer on top of them? Is it necessary? Can they accept requests from a cisco /F5 load balancer?
- What about persistent connection?
- Also we''ll have a mySQL server? Any more info about this?

Answer 1

Load balancing is not a 'standard' Diameter feature. Products perform load balancing by splitting the load between multiple servers based on some criteria. Diameter Load Balancers can do it based on Diameter sessions or other AVPs in the PDU, but even TCP load balancers can be used when you want to split a large number of clients between a few servers.

Failover is specified in 3588 (hence a conforming implementation should implement it). This kicks in when the primary server (one with lowest weightage and hence highest priority) fails/is not reachable. Diameter stack tries to forward requests to the next best server in the routing table.

Answer 2

The generic difference between loadbalancer and Failover is :

In case of load balancer, traffic is routed to more than one (2-3 or more) sites,nodes or network elements to have an equal sharing of incoming traffic. This is achieved by filtering traffic on the basis of subscriber type, location type etc. At a time all the sites are active and handle the traffic.

While in case of Failover, the primary node handles the traffic and secondary is (in healthy status) acts as a redundant node. In case of primary node - failure, or disconnect, the secondary becomes active and starts acting as traffic-handler.