Virtual Machine Expected Network Bandwidth Clarification

Question

Hello All,

I would like to get clarification on information listed on the FSv2 Virtual Machine series spec page.

The value for "Expected network bandwidth (Mbps)", does it reflect a maximum total bandwidth limit (in AND out) or is the value per direction?

As an example:

Standard_F64s_v2 - Expected network bandwidth is 28000 Mbps = 28 Gbps = 3.5GB/s
Standard_F72s_v2 - Expected network bandwidth is 30000 Mbps = 30 Gbps = 3.75GB/s

Given the transfer rates above (take the F64s_v2 for instance) and assuming that the file is read from memory (as opposed to a slower HDD or SSD drive), should it be possible to send data at 3.5 GB/s AND receive data at 3.5 GB/s simultaneously (for a total of 7.0 GB/s) or is the 3.5 GB/s shared between the sending and receiving?

What is the best way to determine if the VM is maxing out the bandwidth during a particular timeframe? On the VM's metrics page, the best indicator available is the "Network In Total" and "Network Out Total", which displays the amount of data transferred for a particular time slice (in this case, per minute)

So, if "Network In" is 1.5 GB and "Network Out" is 4.2 GB, the total data transferred is 5.7 GB for 60 secs (which means the rate is closer to 0.095 GB/s).

CPU during this time is not maxing out.

Looking for feedback.

Alex

Answer 1

@Alex W Apologies for the delay in response and all the inconvenience caused because of the issue.

The network bandwidth allocated to each virtual machine is metered on egress (outbound) traffic from the virtual machine. All network traffic leaving the virtual machine is counted toward the allocated limit, regardless of destination. For example, if a virtual machine has a 1,000 Mbps limit, that limit applies whether the outbound traffic is destined for another virtual machine in the same virtual network, or outside of Azure.

Ingress is not metered or limited directly. However, there are other factors, such as CPU and storage limits, which can impact a virtual machine’s ability to process incoming data.

Bandwidth allocated to a virtual machine is the sum of all outbound traffic across all network interfaces attached to a virtual machine. In other words, the allocated bandwidth is per virtual machine, regardless of how many network interfaces are attached to the virtual machine

In addition to bandwidth, the number of network connections present on a VM at any given time can affect its network performance.

You can find more info here.

This means sending and receiving might depend upon various factor in between and that doesn't necessarily mean that you will get same bandwidth simultaneously.

The mentioned bandwidth is the expected bandwidth which is sum of both incoming and outgoing traffic and is applicable as per your requirement.

Hope it helps!!!

Please "Accept as Answer" if it helped so it can help others in community looking for help on similar topics.