LVS load balancing four
- IP packets without forward chain
1, LVS working on the input chain netfilter kernel space, just as netfilter framework, install iptables command to write rules can act on the already compiled into the kernel netfilter framework. Similarly, ipvs already compiled in the kernel, we just install ipvsadm management command, write rules to take effect.
2, ipvsadm: User-defined space management LVS command-line tool
ipvs: work on the frame of the kernel space input chain, have been compiled into the kernel.
LVS Type:
. 1, the NAT-LVS (NAT): The requested destination address is converted to the real server address. Multi-target DNAT. 
All inbound and outbound traffic will go through director, real server gateway should point director.
2, LVS-DR (direct routing): director and the real server must be in the same physical network, without intermediate routers 
director only process incoming requests, responses, and client directly by the real server
. 3, the LVS-TUN (tunnel): and DR mode Similarly, except in the IP packet encapsulation layer, a tunnel transmission.
Load balancing algorithm:
conventional algorithm (wlc default, is the most likely visible wlc):
. 1, RR: round Robin, polling
2, wrr: weight round robin, weighted round-robin
3, sh: source hash, the original address hash, a session for session binding
4, lc: least connections, based on the least connection
5, wlc: weight least connections, weighted least connections
6, dh: destination hash, acting as a cache available to backend server