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Load Balancing Server
 

Load Balancing Server

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    Load Balancing Server Load Balancing Server Presentation Transcript

    • Server
      Load Balancing
      Presented by:-
      AbhishekPradhan
      5/8/2011 12:52:04 AM
      1
    • Contents
      • Introduction to Server Load Balancing
      • Concepts of Server Load Balancing
      • Components of SLB devices
      • Anatomy of a Server Load Balancer
      • Methods of load balancing
      • Reduce latency and maximize uptime
      • References
      5/8/2011 12:50:57 AM
      2
    • Introduction to Server Load Balancing
      Server 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 simplified
      5/8/2011 12:50:57 AM
      3
    • A load balancer performs the following functions :-
      • Intercepts network-based traffic (such as web traffic) destined for a site.
      • Splits the traffic into individual requests and decides which servers receive individual requests.
      • 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 AM
      4
    • Concepts of Server Load Balancing
      • OSI Layer Model
      It 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 AM
      5
    • Components of SLB devices
      • VIPs
      Virtual IP (VIP) is the load-balancing instance where the world points its browsers
      to get to a site. A VIP has an IP address, which must be publicly available to be
      useable. Usually a TCP or UDP port number is associated with the VIP, such as
      TCP 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 AM
      6
      • 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 its
      place and function, with little or no impact on operations as a whole.
      5/8/2011 12:51:02 AM
      7
    • Anatomy of a Server Load Balancer
      SLB 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 Network
      Address Translation (NAT).
      In Figure , you see an IP packet sent from a source address of 208.185.43.202
      destined for 192.168.0.200. This IP header is like the "To" and "From" portions of a
      letter sent through the post office. Routers use that information to forward the
      packets along on their journeys through the various networks.
      Figure . An IP packet header
      Mohit
      5/8/2011 12:51:02 AM
      8
    • Methods of load balancing
      Hardware Load Balancing
      Hardware 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 Balancing
      Most 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 AM
      9
    • Reduce latency and maximize uptime
      Server 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 Performance
      Increase 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 scalability
      Load balancers allows new virtual and/or physical server to be added
      transparently, maximizing flexibility, and allowing server applications to scale
      without disruption
      • Maintain persistence
      Persistence is needed in certain server application that manage the client
      state on the server side
      5/8/2011 12:51:02 AM
      10
    • References:
      • Wikipedia .org
      • Google images
      • codeidol.com
      • informit.com
      5/8/2011 12:51:02 AM
      11