Configuring multicast ARP
Microsoft Network Load Balancing (NLB) is a load balancing technology for server clustering developed on Windows Server.
NLB supports load sharing and redundancy among servers within a cluster. To implement fast failover, NLB requires that the switch forwards network traffic to all servers or specified servers in the cluster, and each server filters out unexpected traffic. In a medium or small data center that uses the Windows Server operating system, the proper cooperation of the switch and NLB is very important. For more information about NLB, see the related documents of Windows Sever.
Microsoft NLB provides the following packet sending modes to make the switch forward network traffic to all servers or specified servers:
Unicast mode—NLB assigns each cluster member a common MAC address, which is the cluster MAC address, and changes the source MAC address of each sent packet. Thus, the switch cannot add the cluster MAC address to its MAC table. In addition, because the cluster MAC address is unknown to the switch, packets destined to it are forwarded on all the ports of the switch.
Multicast mode—NLB uses a multicast MAC address that is a virtual MAC address for network communication, for example 0300-5e11-1111.
Internet Group Management Protocol (IGMP) multicast mode—The switch sends packets only out of the ports that connect to the cluster members rather than all ports.
![[NOTE: ]](images/note.png) | NOTE: Multicast ARP is applicable to only multicast-mode NLB. | |
To configure multicast ARP:
Step | Command | Remarks |
|---|---|---|
1. Disable the ARP entry check function. | undo arp check enable | N/A |
2. Configure a static ARP entry. | arp static ip-address mac-address vlan-id interface-type interface-number [ vpn-instance vpn-instance-name ] | Optional. |
3. Configure a static multicast MAC address entry. | mac-address multicast mac-address interface interface-list vlan vlan-id | See IP Multicast Command Reference. |