Does windows cluster Design requires 2 NIC Cards? Is it compulsory??

Question

Hi

Is it compulsory to have 2 NIC cards for windows Cluster 2016/2012/2109 for Production environment (each node will have 2 NIC cards)
I have been building this windows cluster few years, with 2 NIC cards.. as recommended by microsoft..

But recently we had a comment in our team, that windows clusters can build on single NIC cards on each node. I was surprised to support his case by others, and he pointed to the website

https://techcommunity.microsoft.com/t5/failover-clustering/no-such-thing-as-a-heartbeat-network/ba-p/388121

1. In the above blog also explains, the heartbeat packets are small UDP packets around 134 bytes in size so it’s not going to make any difference on the network load either
2. heartbeat or “cluster communication”, yes, but since Windows 2008 you don’t need a dedicated NIC for it according to that blog
3. having a dedicated NIC for heartbeat is not going to reduce the cluster load

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As I building a strong Case on this for 2 NIC cards are compulsory for prod

can you pls let me know your views and recommend websites, with url. Appreciate your help

Your suggestion and guidance extremely valuable.. Thanks

Answer 1

Hi,

As far as I am concerned, with one NIC on each node, the cluster can be setup, and in some degree, we can't say it is single point failure, since the cluster is already work as high availability.

Assume that the NIC on one Cluster node is failed, then the heartbeat to that node will be failed, and then that node will be removed from the Cluster membership, at that time, roles on that node will failover to other possible nodes. The roles in the Cluster will not affect.

However, if the (virtual) switch has issues, cause the hold cluster has a network connection issue, then, the cluster will be down.

Although one NIC on each node is supported to create the SQL cluster, it's highly recommended to add an additional network for the heartbeat, as described above, heartbeat packet is lightweight and important, for SQL services, if there's heavy network traffic, the heartbeat packets will lose, so it's recommended to create an additional heartbeat network to make the cluster more stable.

Thanks for your time!

If the reply could be of help, please help to accept it as an answer, thanks for your cooperation!
Thanks for your time!
Best Regards,
Anne

Answer 2

Im just trying to show case, how does this affect IT operations like managing apps,sql server cluster on windows cluster..with single NIC card per cluster node

Thanks

Answer 3

Hi,

I would like to check if the above reply could be of help? If yes, please help accept it as an answer, so that others meet a similar issue can find useful information quickly. If you have any other concerns or questions, please feel free to feedback.

Best Regards,
Anne