Load Balancing Server
- 1. Server Load BalancingPresented by:-AbhishekPradhan5/8/2011 12:52:04 AM1
- 2. ContentsIntroduction to Server Load Balancing
- 3. Concepts of Server Load Balancing
- 4. Components of SLB devices
- 5. Anatomy of a Server Load Balancer
- 6. Methods of load balancing
- 7. Reduce latency and maximize uptime
- 9. Introduction to Server Load BalancingServer Load Balancing (SLB) may be defined as a process and technology that distributes site traffic among several servers using a network-based device. This device intercepts traffic destined for a site and redirects that traffic to various servers. Figure 1-1. SLB simplified5/8/2011 12:50:57 AM3
- 10. A load balancer performs the following functions :-Intercepts network-based traffic (such as web traffic) destined for a site.
- 11. Splits the traffic into individual requests and decides which servers receive individual requests.
- 12. Maintains a watch on the available servers, ensuring that they are responding to traffic. If they are not, they are taken out of rotation.5/8/2011 12:50:57 AM4
- 13. Concepts of Server Load BalancingOSI Layer ModelIt stands for Open Systems Interconnection model .When referring to load balancers, OSI layers are often mentioned. OSI was developed as a framework for developing protocols and applications that could interact seamlessly. It closely resembles the Internet IP world in which load balancers exist today.5/8/2011 12:50:57 AM5
- 14. Components of SLB devices VIPs Virtual IP (VIP) is the load-balancing instance where the world points its browsersto get to a site. A VIP has an IP address, which must be publicly available to beuseable. Usually a TCP or UDP port number is associated with the VIP, such asTCP port 80 for web traffic. A VIP will have at least one real server assigned to it,to which it will dispense traffic .5/8/2011 12:50:57 AM6
- 15. Servers A server is a device running a service that shares the load among other services. A server typically refers to an HTTP server, although other or even multiple services would also be relevant. A server has an IP address and usually a TCP/UDP port associated with it and does not have to be publicly addressable . Redundancy Redundancy as a concept is simple: if one device should fail, another will take itsplace and function, with little or no impact on operations as a whole.5/8/2011 12:51:02 AM7
- 16. Anatomy of a Server Load BalancerSLB works by manipulating a packet before and after it reaches an actual server. This is typically done by manipulating the source or destination IP addresses of a IP packet in a process known as NetworkAddress Translation (NAT).In Figure , you see an IP packet sent from a source address of 208.185.43.202destined for 192.168.0.200. This IP header is like the "To" and "From" portions of aletter sent through the post office. Routers use that information to forward thepackets along on their journeys through the various networks.Figure . An IP packet headerMohit5/8/2011 12:51:02 AM8
- 17. Methods of load balancingHardware Load BalancingHardware load balancers can route TCP/IP packets to various servers in a cluster. These types of load balancers are often found to provide a robust topology with high availability, but comes for a much higher cost. Pros: Uses circuit level network gateway to route traffic.Cons: Higher costs compared to software versions.Software Load BalancingMost commonly used load balancers are software based, and often comes as an integrated component of expensive web server and application server software packages.Pros: Cheaper than hardware load balancers. More configurable based on requirements. Can incorporate intelligent routing based on multiple input parameters.Cons: Need to provide additional hardware to isolate the load balancer.5/8/2011 12:51:02 AM9
- 18. Reduce latency and maximize uptimeServer load balancing increases the efficiency of your server farm, keeping applications running if servers go down, and forwarding computing requests to the most appropriate server. Maximize PerformanceIncrease the performance of your server farm by running distributed Applications where the load balancer forwards end-users requests to application servers based on pre-defined rules & policies.Increase scalabilityLoad balancers allows new virtual and/or physical server to be added transparently, maximizing flexibility, and allowing server applications to scale without disruptionMaintain persistencePersistence is needed in certain server application that manage the client state on the server side5/8/2011 12:51:02 AM10
- 20. Google images
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