Microsoft NLB issue

[AllBlack]

Hello,

Had a first go at configuring NLB. I configured it in the same manner as my colleague had done

on physical boxes.

I configured it as multicast and everything looks ok within the NLB manager. Unlike with the physical servers,

I can only connect to cluster from the same subnet. I can't ping from a different subnet.

What gives? According to VMware it should not require any changes to the host.

I have tried placing VMs on one host and different hosts. The results remain the same,

only works from the same subnet.

cheers

[Texiwill]

Hello,

Moved to the Virtual Machine and Guest OS forum.

Check out http://www.vmware.com/files/pdf/implmenting_ms_network_load_balancing.pdf for assistance on this as well as http://www.vmware.com/files/pdf/technology/esx35_ip_multicast.pdf

Best regards,

Edward L. Haletky

VMware Communities User Moderator

====

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[happyhammer]

would suggest you create a seperate port group for NLB and set the notify switches setting to NO

[AllBlack]

I haven't had a chance to talk to one of our network engineers but another colleague told me

that when he did a setup on physical hardware that they had update the configuration of the switch

that network ports where connected too.

The VMs on the host are connected through the same network port (trunked) and we make use of several vlans.

I don't see creating another port grop as an issue.

How would updating the physical switch configuration affect the other VMs?

cheers

[kjb007 · Accepted solution]

The key issue here is that the MAC address of the muticast is not learned by the routers in question. This is why you can only ping locally within the smae VLAN. To fix this, you will need to create a static ARP entry on your router(s).

From page 2 of the NLB guide:

Some routers do not support the resolution of unicast IP addresses to multicast MAC addresses, and they discard the ARP reply. As a result, an administrator must add a static ARP entry in the router, mapping the cluster IP address to its MAC address.

-KjB

[happyhammer]

all black i was refering to creating a new port group for NLB in the vSwitch and set this port group to notify switches to NO(load balancing tab) and not at the physical switch level

[djciaro]

I have setup several environments which runs successfully with NL.

KB ref:

I find that the best setup is to configure a seperate VM port group for

the NLB in your virtual switch and disable "notify switches" assign

this to your adapters used for NLB in multicast mode.

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