VMWare and multiple IP addresses

I am fairly new to VMWare so we hired a consultant to help configure our VM network and create a cluster of 3 hosts. We also invested in a SAN that has 4 10GB NIC's and a 10GB switch to connect to the VM Hosts. On one of the VM hosts we have an SQL 2012 server and it has 3 virtual NIC cards assigned to it each with their own IP on the same subnet.

I have been reading on the net that this is acceptable however when I ping the server it returns any one of the three addresses which I guess it is ok but when I look at the System logs I see errors stating "A duplicate name has been detected on the TCP network.  The IP address of the computer that sent the message is in the data. Use nbtstat -n in a command window to see which name is in the Conflict state." this doesn't seem right however if multiple IP addresses can be added and used on one machine then I would think this error can be ignored. Is that right and if not how do I correct this issue?
TimSr. System AdminAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Your issue is not really anything to do with VMware vSphere. Same issue would happen if you connected any computer with three nics to a network.

As an aside, if you only have a single 10GBe switch, this could be a single point of failure for your storage network, if it fails.

I am fairly new to VMWare so we hired a consultant to help configure our VM network and create a cluster of 3 hosts. We also invested in a SAN that has 4 10GB NIC's and a 10GB switch to connect to the VM Hosts. On one of the VM hosts we have an SQL 2012 server and it has 3 virtual NIC cards assigned to it each with their own IP on the same subnet.

why does the VM have three network interfaces ?

I have been reading on the net that this is acceptable however when I ping the server it returns any one of the three addresses which I guess it is ok but when I look at the System logs I see errors stating "A duplicate name has been detected on the TCP network.  The IP address of the computer that sent the message is in the data. Use nbtstat -n in a command window to see which name is in the Conflict state." this doesn't seem right however if multiple IP addresses can be added and used on one machine then I would think this error can be ignored. Is that right and if not how do I correct this issue?

The issue is probably DNS has three IP Addresses for the server, and it's issuing different IP Addresses Round Robin style to requests.

remove two IP Addresses.

as for duplicate name conflict, that is also to be expected because the same name is being broadcast on the same IP Network?

WHY do you have THREE IP Addresses on the same network ?

Disable NETBIOS on the other two network interfaces.

Did you Consultant setup this computer ?
1
Brian BEE Topic Advisor, Independant Technology ProfessionalCommented:
Virtual or physical, having three addresses on the same subnet could cause problems. Unless those three NIC cards are assigned to different networks in the VM settings, I don't see the point. In the end, all the data still goes over the same wires to the same switch.
0
TimSr. System AdminAuthor Commented:
The server has three NIC's because he said that would fix a potential bottleneck on the network. I disagreed with his logic however my boss said to go with his suggestions because he has more 'Experience'. I came from the school where you are supposed to go one name to one IP otherwise you will experience congestion and collisions.

Yes, the consultant setup this new server. With that said I have a ton of questions now. The SAN that is hosting the data for at least 8 VM's has 4 10GB NIC's all with different IP's assigned to it, will that cause a problem? Those IP's are all on the same subnet as well and this was done to provide more throughput.

It also sounds like my train of thought being 1 to 1 is correct but when we are talking SAN and Clustered Hosts\VM Machines I am not so sure on what best practices would be.  

It looks like I need to make a bunch of changes this weekend on the network but first want to make sure I cover all my bases.
0
Ultimate Tool Kit for Technology Solution Provider

Broken down into practical pointers and step-by-step instructions, the IT Service Excellence Tool Kit delivers expert advice for technology solution providers. Get your free copy now.

Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
The server has three NIC's because he said that would fix a potential bottleneck on the network. I disagreed with his logic however my boss said to go with his suggestions because he has more 'Experience'. I came from the school where you are supposed to go one name to one IP otherwise you will experience congestion and collisions.

what a lot of foo!!!! and to be honest with you, we see this every week, because the Consultant is paid a lot of cash, go with it because he's the Consultant! LOL!

I would give your BOSS, the SQL Best Practice guide below to read this Christmas and compare and contrast how your server has been setup, compared to this Best Practice!

(we came from a school of Question Everything, and Trust No One!)

I hope you are using and have instaled VMware Tools which is not optional, and use the VMXNET3 interface, this will give you a 10GBe interface in the VM.

and then it depends on how you have teaming configured on the host.

SQL bottlenecks are likely to be CPU and Disk I/O.

Have a read of this document, on how to architect a SQL server, and compare what you have... I think you'll be upset with your config..

Architecting Microsoft SQL Server on VMware vSphere® B E S T P R A C T I C E S G U I D E M A R C H 2 0 1 7

I really think it would be better if you bundled these questions on EE into different questions...

es, the consultant setup this new server. With that said I have a ton of questions now. The SAN that is hosting the data for at least 8 VM's has 4 10GB NIC's all with different IP's assigned to it, will that cause a problem? Those IP's are all on the same subnet as well and this was done to provide more throughput.

It also sounds like my train of thought being 1 to 1 is correct but when we are talking SAN and Clustered Hosts\VM Machines I am not so sure on what best practices would be.


To be honest with you, without understanding, the configuration, SAN type, networking, switch.... it's difficult to know...

By my first impressions of your "Consultant" that configures an SQL server with three network interfaces in a VM on VMware, and says

The server has three NIC's because he said that would fix a potential bottleneck on the network.

Well the next time you see him, you can tell him, he's just won an Award for the Best Consultant of the Year 2017! and for that he has won a sticky chicken!

We are going to use that quotation from now on next year in our VMware Training Academy on How NOT to configure a VM.
1

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Aaron TomoskySD-WAN SimplifiedCommented:
setting up sql with multiple disks can avoid I/O limitations even when virtualized. maybe the consultant got disks and NICs confused? :)
1
David Johnson, CD, MVPOwnerCommented:
That or teamed the NIC's
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Virtualization

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.