windows NLB troubleshoot

Scott Gao 291 Reputation points


I had stuck at NLB problem few days. I enable multicast NLB and can ping within member self. But I can not ping from client within same subnet (layer 2) network.

I am on a vmware esxi 7 host. All server and client on same host.

below link said I don't need have any settings on vmware if use multicast.

for physical switch support multicast, I know mainly have below 2 settings.

  1. setup multiport mac

mac-address multiport mac-address interface interface_number to interface_number vlan vlan-id

  1. setup arp static

arp static IP-address mac-address

however, my test did not pass a router. it should work without any settings.

would you please guide me how to troubleshoot?
Very appreciate for your help.


Windows Server
Windows Server
A family of Microsoft server operating systems that support enterprise-level management, data storage, applications, and communications.
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Accepted answer
  1. Limitless Technology 39,506 Reputation points

    Hi there,

    When using NLB in multicast or unicast mode, routers need to accept proxy ARP responses (IP-to-network address mappings that are received with a different network source address in the Ethernet frame).

    Make sure that your router has proxy ARP support turned on. You can also set a static ARP entry to keep proxy ARP support disabled in the router.

    In some cases internet control message protocol (ICMP) to the cluster is blocked by a router or firewall.Allow ICMP traffic through the router or firewall. Be aware that this may expose your system to additional security risk.

    --If the reply is helpful, please Upvote and Accept it as an answer--

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