On the off chance that you're unable to put through to a Windows Server Network Load Balancing (NLB) Virtual IP address designed for Multicast Mode it is since of the way your Cisco switch interatomic with Microsoft NLB.

Symptoms

- Cannot ping Windows Server NLB Virtual IP address

- Cannot connect Windows Server NLB Virtual IP address

- NLB Multicast Mode not working

We would not go into the details of how NLB works, client requests are distributed across different servers. To configure NLB, you can use three modes:

- Multicast

- Unicast

- IGMP

Multicast Mode

When utilizing Multicast mode, the cluster individuals will react to ARPs utilizing their virtual IP address and a multicast MAC address. Without the right configuration on the switch you may not be able to associate to the Virtual IP address.

This will not work because within the ARP request packet is a unicast IP address and a multicast MAC address. Investigating it can be baffling but a Cisco switch will overlook this. Underneath is the arrangement to be done on the switch.

Cisco Switch Configuration

To resolve the issue, make a inactive ARP section for the Virtual IP Address to the NLB MAC address. At that point make a inactive MAC address section to the VLAN and interfacing utilized by the cluster.

In my case, my virtual IP address is 192.168.10.10 with MAC address of 03bf.0a65.05fa. That IP address is on VLAN 10 and the servers' interfacing are portion of a port-channel, both Port-Channel1 and Port-Channel2.

configuration is as follows:

arp 192.168.10.10 03bf.0a65.05fa

mac address-table static 03bf.0a65.05fa vlan 10 interface Port-Channel1 Port-Channel2

A few arrangement things to note.. not all Cisco switches will bolster a inactive passage of a MAC address to numerous interfacing. In my case I am employing a Cisco Catalyst 4500-X in VSS mode. The servers had two arrange interfacing designed into an EtherChannel.
https://mobileinfoworld.com/windows-server-nlb-virtual-ip-address-by-cisco-switch/