Nimbostratus
Can anybody explain me core working of LC. Also i am unable to understand how LC remove BGP reliance. As for case of BGP routes are advertised by ISP to outside world who then can access internal servers through avaiable path but i wonder how can LC can achieve it?
Altostratus
For inbound traffic, you create NS records on your DNS servers.
Example for a DNS zone called sample.com
www IN NS lc.sample.com
On the LC, you'd create a Virtual Server (virtual IP essentially) and pool (group of servers to which you send traffic. After that, you create an "inbound wide ip" which basically says "www.sample.com" points to Virtual Server "x"
For outbound traffic, you'd simply create a "gateway pool" which contained your ISP routers. You'd then create a Virtual Server to handle your outbound traffic and associate that gateway pool with it.
As far as your BGP reliance question, you simply don't need one set of IP addresses with LC. Since you're load balancing outbound across multiple ISPs and LC will give you link-affinity, it doesn't matter which router you go out. For inbound traffic, DNS hands out an IP for whichever ISP is chosen. Obviously, the ISP still needs to tell the world how to get to your IP space, you simply don't need to own IP addresses yourself or manage your own BGP configs.
Make sense?