Demystifying Azure VMs bandwidth specification – F-series

As you may know Microsoft specifies the bandwidth of Azure VMs with low, moderate, high, very high and extremely high. As Yousef Khalidi, CVP Azure Networking, has written in his blog post in March, Microsoft will provide specific numbers to each Azure VM size in April.

When our world-wide deployment completes in April, we’ll update our VM Sizes table so you can see the expected networking throughput performance numbers for our virtual machines.

https://azure.microsoft.com/en-us/blog/networking-innovations-that-drive-the-cloud-disruption/

I have run some network performance tests on each F-series VM size to get the numbers for it. For my tests I have used the NTttcp utility by Microsoft.

-> https://gallery.technet.microsoft.com/NTttcp-Version-528-Now-f8b12769

My test setup was the following:

  • send-crp1 as the sender VM with the internal IP address 10.0.0.4
  • receive-crp1 as the receiver VM with the internal IP address 10.0.0.5

Both VMs were deployed as F1 to start the tests with and were running Windows Server 2016.

NTttcp option on sender VM:

ntttcp.exe -s -m 8,*,10.0.0.5 -l 128k -a 2 -t 15

NTttcp option on receiver VM:

ntttcp.exe -r -m 8,*,10.0.0.5 -rb 2M -a 16 -t 15

Before running the tests it is advisable to disable the Windows firewall on the systems.

NetworkPerformance1

Here are the results for all F-series VM sizes. So you get an idea what you can expect, when you are reading network bandwidth is high. But keep in mind that depending on the CPU cores the network bandwidth varies.

SizeCPU coresMemory: GiBNetwork bandwidthMeasured network bandwidth
F112Moderate750 Mbit/s
F224High1,5 Gbit/s
F448High3 Gbit/s
F8816High6 Gbit/s
F161632Extremely high12 Gbit/s

The most powerful VM size regarding network bandwidth without the use of RDMA is the D15_v2 with the accelerated networking option.

NetworkPerformance2

SizeCPU coresMemory: GiBNetwork bandwidthMeasured network bandwidth
D15_v220140Extremely high24 Gbit/s

I am looking forward to the specific numbers to get published in the Azure documentation as I mentioned and quoted it at the beginning of this blog post.

-> https://docs.microsoft.com/en-us/azure/virtual-machines/windows/sizes

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