Description

Network Load Balancing Services (NLBS) is a Microsoft implementation of clustering and load balancing that is intended to provide high availability and high reliability, as well as high scalability.

Symptoms

J-series or SRX platform is unable to learn the Microsoft Network Load Balancing virtual MAC address.

Solution

The Microsoft Network Load Balancing can be configured either for unicast or multicast mode. If the NLB is configured using multicast, while the cluster uses a unicast IP address, it will associate it with a multicast MAC address. Thus, any IP packets using the cluster IP address will be forwarded using this multicast MAC.

In the event where NLB is configured using multicast, the J-series or SRX device can be configured to receive this MAC address by hard-coding the interface paired with the NLB as follows:

set interfaces ge-0/0/1 unit 0 family inet address 1.1.1.1/24 arp 1.1.1.10 multicast-mac 01:00:5e:00:00:04
Where the parameters are as follows:
1.1.1.1 = the JSRX interface IP address
arp = the NLB address
multicast-mac = the virtual MAC address that belongs to the NLB