NLB Microsoft with Switch L3

Unanswered Question
Aug 27th, 2007
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My problem that have two vlans in switch L3, one with servers(vlan 2 ), and others with network users(vlan 1).

In vlan 2 i have servers and one cluster NLB of the Microsoft. Well, When I am in vlan 1, i want test ping

virtual ip of the cluster and don`t have returns, the individual servers of the cluster and others servers, test ping

and function normally. In local vlan 2, i test ping in virtual ip of the cluster and functional. My problem is

in other subnet. The cluster is function multicast option. Can be problem of the configuration in switch (IGMP,etc...)?


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Overall Rating: 5 (1 ratings)
blakewebb Thu, 09/06/2007 - 16:17
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You need to manually add an ARP entry to the L3 pointing at the virtualized MAC of the NLB. Because it is using a multicast MAC for the NLB the L3 device will not cache the Unicast IP associated with that MAC and therefore can't route any traffic properly.

Use the following example to add static ARP:


(where X.X.X.X is the NLB IP and XXXX.XXXX.XXXX is the NLB MAC

You may need to add a static CAM entry too to map the NLB MAC to the proper ports...see the following articles and you should be g2g. Let me know if this helps.


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