Chapter 45 NLB
XGS4600 Series User’s Guide
429
45.1.2 What You Need to Know
NLB
Network Load Balancing (NLB) is a feature developed by Microsoft. NLB enhances the performance
reliability for critical applications by sharing traffic with multiple servers in a cluster using TCP/IP protocol.
Each server of a cluster tackles a copy of a traffic. You can create a cluster by grouping up to 32 servers
together.
If a server in a cluster fails, traffic will be redistributed to the other operating servers. When the server is
back in service, it will join the cluster automatically and share the traffic.
Unicast Mode
NLB replaces the real MAC addresses of the servers in a cluster with a unicast MAC address. Each server
uses the same unicast MAC address, and a switch cannot map the unicast MAC address to a port. This
forces a switch to flood traffic meant for the cluster to all ports of the switch to make sure the traffic is
forwarded to the right destination.
The servers in a cluster cannot communicate with each other, because they use the same unicast MAC
address.
Multicast Mode
NLB assigns a multicast MAC address to the servers in a cluster. Therefore, each server has two MAC
addresses, the real MAC address and the multicast MAC address.
Create static ARP entries on a switch for the servers, so the switch will only forward traffic to the servers of
the cluster.
The servers in a cluster can communicate with each other, because they keep their real MAC address
and already have their own IP addresses.
45.2 MAC Forwarding
Use this screen to configure to which MAC addresses and ports the Switch should forward the incoming
NLB traffic.
Click Advanced Application > NLB in the navigation panel to display the screen as shown.
Note: The following screens cannot have duplicate settings as the Advanced Application >
NLB screen.
• Advanced Application > Static MAC Forwarding
• Advanced Application > Static Multicast Forwarding
• Advanced Application > Filtering
To Next Page
Loading...
