When the host finishes processing the request, it sends its response back to the load balancer, which in turn relays the response back to the external client. (A host may then invoke the services of other hosts to help process the request.) Upon receiving a request for a particular application, the load balancer forwards it to one of the hosts that handles the application. Such a load balancer is sometimes referred to as a “layer-4 switch” since it makes decisions based on the destination port number (layer 4) as well as destination IP address in the packet.
Inside the data center, the external requests are first directed to a load balancer whose job it is to distribute requests to the hosts, balancing the load across the hosts as a function of their current load.Ī large data center will often have several load balancers, each one devoted to a set of specific cloud applications. To support requests from external clients, each application is associated with a publicly visible IP address to which clients send their requests and from which they receive responses. Load BalancingĪ cloud data center, such as a Google or Microsoft data center, provides many applications concurrently, such as search, email, and video applications. Owing to its features, the layer 3 switches can single handedly manage the traffic controlling and routing in LANs utilizing bandwidth hungry devices.Some vendors foresee higher-layer switches that examine layer 5, 6, or 7 information to provide more control over prioritizing application traffic, but this might be just vendor hype. This configuration enables it to manage the VLAN routing at the local level and optimizes the work efficiency of router enabling it to perform long distance data transmission.
In such networks, each individual switch is configured with a main router. Layer 3 switches are used in several high density WANs comprising overloaded routers. They can support bandwidth-hungry end-user applications and resources. This flexibility makes them an ideal choice for the fast-growing enterprises, where high speed networks are implemented. When used in combination with layer 2 switches, these switches can accommodate any number of users, and help reduce the need for increasing bandwidth or adding extra layer 3 switches or making any additional investments. These switches are commonly used in the fast growing campuses, organizations, as well as data centers, where high density networking is involved.
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