Network Load Balancing Essay Example | Topics and Well Written Essays - 500 words

Network Load Balancing - Essay Example The high availability is achieved by early detection of host failures and re-distributing their workload to other cluster hosts. Thus, failure of one host does not affect the services. Users would still feel as if they are being served by the same server despite of the fault. The downtime is thus, eliminated. This is the default mode in which all the cluster servers are given the same MAC address (Cisco, 2009). Thus, each packet (addressed to this MAC address) reaches all the cluster servers. Even if one server is unavailable or cannot process the request due to workload, another server will reply to the data packet. One problem with unicast mode is that if all servers are assigned the same MAC address and are connected to the same switch, the switch will be unable to identify the destination (due to same address of all servers). It is not possible to have two ports on same switch with same MAC address. The unicast mode addresses this problem with MAC address masking. The MAC address of each server is masked with a bogus MAC. So when the switch relays a packet, the NLB array decodes the masked address and then transfers the packet to destination (Cisco, 2009).