Dell SmartFabric OS10 User Guide Release 10.5.3

Network load balancing

NLB enhances the reliability and scalability of server applications such as web servers, proxy servers, FTP servers, VPN, and so on.

Network load balancing (NLB) in Microsoft Windows servers allows you to manage two or more servers as a single virtual cluster.

NLB enables all hosts (servers) in the cluster to be addressed by the same set of IP addresses (Cluster IP). Interfaces through the SmartFabric OS10 switch where the cluster is connected become members of a single VLAN, called the NLB VLAN.

You can configure the NLB cluster to operate either in Unicast or Multicast modes. In Unicast mode, all the server NIC adapters have the same Unicast MAC address. In multicast mode, NLB converts the NLB virtual IP (VIP) address to an NLB Multicast MAC address. This MAC address has the following format: 03-BF-XX-XX-XX-XX.

NLB also ensures that the primary IP address of the cluster resolves to the NLB MAC address as a static ARP entry. Although the individual network adapters retain their original MAC addresses, the NLB traffic is addressed to the NLB MAC address.

SmartFabric OS10 provides configuration commands to create an NLB cluster VLAN by associating the NLB cluster IP and MAC to a VLAN.

You must provide lists of interfaces to which the NLB cluster hosts (servers) connect. If you do not configure an interface list, the traffic that is destined for the NLB cluster IP forwards to all member interfaces of the VLAN.