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We're running a Microsoft NLB cluster in multicast mode as a loadbalancer. Using our old Cisco IOS switches we propagate access to the cluster to our branches using a static ARP entry in the core router:

arp 03bf.0a14.01e2 ARPA

But how does one solve this using non-IOS based Cisco hardware such as the SG300 series? Adding a static ARP entry results in an error message telling the user that the hardware address needs to be a valid unicast MAC address.

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We run MS NLB as well, and you only need the arp entry where the NLB host is locally, not on every other network device in your network. So whatever switch your NLB cluster is in, set the static arp there, and no where else. It will work just fine.

And you only need the mac address of the cluster IP. If you happen to have the cluster spread across two or more switches, then you would need that arp entry within each switch that the NLB is spread across.

Edit 1:

Check out this article:

Just make sure you're only adding the arp where the NLB is terminated. My suggetion would be to terminate the NLB into a more modern switch or set your NLB group to Unicast instead. Also, make sure you're running the "CatOS" commands and not the "IOS" commands. I think your switch is running the catOS. You'll see an example in the cisco link.

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Thanks for your response. But the problem is that I can't figure out how to add a multicast ARP entry and map it to an IP address using the specific Cisco SG300 family. – Fredrik Hedberg Jan 23 '12 at 7:14

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