Static ARP entries on NX-OS

Fryguy — Thu, 28 Oct 2010 13:55:10 +0000

Oh the joys of Microsoft Network Load Balancing (NLB). One of the wonderful ways that it is usually configured is using a Multicast MAC address utilizing a Unicast IP address. Needless to say, most network devices do not like that and thus have problems when devices outside the local LAN attempt to connect to the NLB address. In order to work around this problem you need to configure a static ARP entry on the gateway so that the devices know how to get to the server.
On IOS, this is not so hard as you configure the a static ARP entry (arp 10.1.1.99 0300.5e11.1111). That command there on the gateway will usually get things working. You may also need to define where that MAC address lives – and the command to do that would be mac-address-table static 0300.5e11.1111 vlan 200 interface fa2/3 fa2/4 This information was obtained from a Cisco document can be found here if you need more information – http://www.cisco.com/en/US/products/hw/switches/ps708/products_configuration_example09186a0080a07203.shtml
Now, on the NX-OS it is a little different as you need to configure the static ARP entry under the VLAN interface in order for it to work:
interface Vlan100
no shutdown
description [—-[ Standard VM VLAN ]—-]
no ip redirects
ip address 10.1.1.2/24
ip arp 10.1.1.99 0300.5e11.1111
N7K1# sh ip arp | inc 1111
10.1.1.99 – 0300.5e11.1111 Vlan100

Nlb - Tag - Fryguy's Blog

Static ARP entries on NX-OS