2008 R2 RDP NLB setup
I have two 2008 R2 Remote Desktop servers. Both have dual NICs.
Server 1 - NIC 1: 10.33.1.110 NIC 2: 10.33.1.91
Server 2 - NIC 1: 10.33.1.111 NIC 2: 10.33.1.92
At this point I can ping all these addresses from another client. I can RDP into any of these addresses as well.
I add the NIC 2 IPs to an NLB cluster and assign the cluster 10.33.1.90.
The moment I do this, from any client I can no longer ping the NIC 2 addresses or the cluster address and RDP only works on NIC 1.
I can ping .90 .91 and .92 from Server 1 or Server 2 but not from any client.
What am I missing?
Server 1 - NIC 1: 10.33.1.110 NIC 2: 10.33.1.91
Server 2 - NIC 1: 10.33.1.111 NIC 2: 10.33.1.92
At this point I can ping all these addresses from another client. I can RDP into any of these addresses as well.
I add the NIC 2 IPs to an NLB cluster and assign the cluster 10.33.1.90.
The moment I do this, from any client I can no longer ping the NIC 2 addresses or the cluster address and RDP only works on NIC 1.
I can ping .90 .91 and .92 from Server 1 or Server 2 but not from any client.
What am I missing?
For that you need to understand difference between unicast and multicast NLB
In unicast actual network card MAC is getting overlapped with original MAC address
When you add two servers in unicast mode, both network cards MAC is replaced by virtual MAC
Technically you can't communicate within nodes having same MAC address
Thats why you need to use two network cards in case of unicast NLB
As opposed, in Multicast, virtual MAC is appended to original MAC address of members
So, you have two MAC addresses on network card. One is its own and another is virtual MAC
obviously two servers can communicate with eath other even if you have single network card
You can check ipconfig /all properties of unicast nlb servers and multicast nlb servers for proof
http://technet.microsoft.com/en-us/library/cc782694(v=ws.10).aspx
http://social.technet.microsoft.com/Forums/forefront/en-US/969f37a0-6838-4d1d-a56a-e35aa9a780f5/when-to-use-nlb-unicast-or-multicast?forum=Forefrontedgegeneral
http://ptgmedia.pearsoncmg.com/images/0789728494/webresources/A011203.html
Mahesh
In unicast actual network card MAC is getting overlapped with original MAC address
When you add two servers in unicast mode, both network cards MAC is replaced by virtual MAC
Technically you can't communicate within nodes having same MAC address
Thats why you need to use two network cards in case of unicast NLB
As opposed, in Multicast, virtual MAC is appended to original MAC address of members
So, you have two MAC addresses on network card. One is its own and another is virtual MAC
obviously two servers can communicate with eath other even if you have single network card
You can check ipconfig /all properties of unicast nlb servers and multicast nlb servers for proof
http://technet.microsoft.com/en-us/library/cc782694(v=ws.10).aspx
http://social.technet.microsoft.com/Forums/forefront/en-US/969f37a0-6838-4d1d-a56a-e35aa9a780f5/when-to-use-nlb-unicast-or-multicast?forum=Forefrontedgegeneral
http://ptgmedia.pearsoncmg.com/images/0789728494/webresources/A011203.html
Mahesh
ASKER
Your information is a little dated as 2008 R2 does not require two network cards any more to do unicast. That is also irrelevant since I am using two NICs.
Unfortunately, this doesn't address the question of why unicast does not work in this situation while multicast does. I'm starting to think it may be related to the fact that the servers are running in a Virtualbox environment (something I neglected to add).
Unfortunately, this doesn't address the question of why unicast does not work in this situation while multicast does. I'm starting to think it may be related to the fact that the servers are running in a Virtualbox environment (something I neglected to add).
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This issue was never actually resolved, although I believe the unicast problem is due to a failure in VirtualBox to handle things properly. I have left this open for quite some time hoping that I or someone else could shed more light on the issue, but at this point I think I will just close it and reward Mahesh for his efforts.
ASKER
Not a solution, but a lot of research and information.
Yes, you are absolutely right
Practically on physical servers having NLB you can't communicate between Unicast NLB members as there MAC address is same, but with NLB VIP external systems can communicate with them and then requests get routed to NLB members.
when virtualization is came to picture as weather you do unicast with one NIC, those are fake \ virtual network cards only and hyper-v \ VMware \ other virtualization software will manage to work with them somehow (because hypervisor host network adapter is intact) but its actually workaround and some times you might face issues.
In case of VMware virtual machines, they recommends multicast NLB with single NIC
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1556
http://social.technet.microsoft.com/Forums/exchange/en-US/d231d1e0-30f0-4a1e-8226-18a705b715c1/windows-nlb-vmware-e2k10-cas-array?forum=exchangesvravailabilityandisasterrecoverylegacy
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1006580
In case of Hyper-V, there is known issue exists with Unicast NLB
http://blogs.technet.com/b/networking/archive/2010/02/12/cannot-access-the-virtual-or-dedicated-ip-address-of-an-nlb-node-guest-running-in-unicast-mode-on-windows-server-2008-r2-hyper-v.aspx
The purpose of above articles, there may be bug having with Virtual Box as well
You can check with there support blog as i have not worked with Virtual Box
Mahesh
Practically on physical servers having NLB you can't communicate between Unicast NLB members as there MAC address is same, but with NLB VIP external systems can communicate with them and then requests get routed to NLB members.
when virtualization is came to picture as weather you do unicast with one NIC, those are fake \ virtual network cards only and hyper-v \ VMware \ other virtualization software will manage to work with them somehow (because hypervisor host network adapter is intact) but its actually workaround and some times you might face issues.
In case of VMware virtual machines, they recommends multicast NLB with single NIC
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1556
http://social.technet.microsoft.com/Forums/exchange/en-US/d231d1e0-30f0-4a1e-8226-18a705b715c1/windows-nlb-vmware-e2k10-cas-array?forum=exchangesvravailabilityandisasterrecoverylegacy
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1006580
In case of Hyper-V, there is known issue exists with Unicast NLB
http://blogs.technet.com/b/networking/archive/2010/02/12/cannot-access-the-virtual-or-dedicated-ip-address-of-an-nlb-node-guest-running-in-unicast-mode-on-windows-server-2008-r2-hyper-v.aspx
The purpose of above articles, there may be bug having with Virtual Box as well
You can check with there support blog as i have not worked with Virtual Box
Mahesh
ASKER