Testing Network Speed Between Azure China and Azure Global for B1s VM

Background

Some businesses choose to deploy their systems across both Azure China and Azure Global. For these systems to function effectively, it is crucial that their communication over the internet performs well. To assess the current state of the network between Azure China and Azure Global, I conducted a series of tests and would like to share the results.

Targeted:

• Azure Virtual Machines with the B1s size

Not Targeted:

• Azure Virtual Machines with accelerated networking (typically B12ms, B16ms, B20ms, or F-series)
• Azure ExpressRoute (primarily an option for large enterprises)

The goal of these tests is not to achieve the highest possible network speed or to promote Azure. This is why I intentionally avoided using high-end VM and network configurations. My aim is to provide a realistic representation of what individuals and small businesses in China typically experience.

Test Method

I use iPerf3 to perform the tests. The method is fully explained in my previous blog post "Test Network Speed Between Azure VMs Using iPerf". 

• VM configuration
  • System: Ubuntu Server 22.04 LTS
  • Size: B1s
  • Disk: Standard SSD
  • NSG: Allow TCP 5201 port
• Azure China Regions used
  • China East 2
  • China North 2
• Azure Global Regions used 
  • East Asia
  • Southeast Asia
  • Japan East
  • Japan West
  • Korea Central
  • West US
  • East US
  • Australia East
  • West Europe
• 3 test runs for each VMs from Azure China to Azure Global

Cloud init content

#cloud-config
runcmd:
  - apt update && apt upgrade -y
  - apt install iperf3 -y

Ubuntu Server is using the following TCP congestion control

edi@****:~$ sysctl net.ipv4.tcp_available_congestion_control
net.ipv4.tcp_available_congestion_control = reno cubic bbr
edi@****:~$ sysctl net.ipv4.tcp_congestion_control
net.ipv4.tcp_congestion_control = bbr

Keep in mind, these tests only represent results in Feb 2023. Microsoft could change the network configuration any time. So, these test results are only for your reference. Please do your own test whenever you need.

About Azure's Network Bandwidth Limit

You can find expected network bandwidth for varied sizes of VMs here. Most series have a table with networking specifications in the last column titled, Max NICs / Expected network performance (Mbps).

However, for B series VMs, including the B1s I used in these tests, does not have information about network bandwidth limit. According to information from Microsoft product team, B series does not provide a consistent level of network performance, this is why they don't publish network bandwidth limit information about it. This is also one of the reasons why I am writing this post.

Test Example

I am doing the same process for each DC location, to keep this post short and clean, I do not post every test run output here. You can find the information in the "Conclusion" section of this post.

Datacenter: China East 2 - East Asia

Note: Sensitive host name and IP address information is masked as `*`.

Test run #1

edi@****:~$ iperf3 -c *.*.*.* -p 5201 -t 10
Connecting to host *.*.*.*, port 5201
[  5] local 10.1.0.4 port 54568 connected to *.*.*.* port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  68.0 MBytes   571 Mbits/sec    0   6.04 MBytes
[  5]   1.00-2.00   sec  87.5 MBytes   734 Mbits/sec    0   6.04 MBytes
[  5]   2.00-3.00   sec  86.2 MBytes   723 Mbits/sec    0   6.04 MBytes
[  5]   3.00-4.00   sec  87.5 MBytes   734 Mbits/sec    0   6.04 MBytes
[  5]   4.00-5.00   sec  87.5 MBytes   734 Mbits/sec    0   6.04 MBytes
[  5]   5.00-6.00   sec  86.2 MBytes   723 Mbits/sec    0   6.04 MBytes
[  5]   6.00-7.00   sec  87.5 MBytes   734 Mbits/sec    0   6.04 MBytes
[  5]   7.00-8.00   sec  87.5 MBytes   734 Mbits/sec    0   6.04 MBytes
[  5]   8.00-9.00   sec  87.5 MBytes   734 Mbits/sec    0   6.04 MBytes
[  5]   9.00-10.00  sec  87.5 MBytes   734 Mbits/sec    0   6.04 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec   853 MBytes   716 Mbits/sec    0             sender
[  5]   0.00-10.06  sec   852 MBytes   711 Mbits/sec                  receiver

Test run #2

edi@****:~$ iperf3 -c *.*.*.* -p 5201 -t 10
Connecting to host *.*.*.*, port 5201
[  5] local 10.1.0.4 port 54568 connected to *.*.*.* port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  67.1 MBytes   563 Mbits/sec    0   6.01 MBytes
[  5]   1.00-2.00   sec  86.2 MBytes   723 Mbits/sec    0   6.01 MBytes
[  5]   2.00-3.00   sec  85.0 MBytes   713 Mbits/sec    0   6.01 MBytes
[  5]   3.00-4.00   sec  85.0 MBytes   713 Mbits/sec    0   6.01 MBytes
[  5]   4.00-5.00   sec  86.2 MBytes   724 Mbits/sec    0   6.01 MBytes
[  5]   5.00-6.00   sec  86.2 MBytes   723 Mbits/sec    0   6.01 MBytes
[  5]   6.00-7.00   sec  85.0 MBytes   713 Mbits/sec    0   6.01 MBytes
[  5]   7.00-8.00   sec  85.0 MBytes   713 Mbits/sec    0   6.01 MBytes
[  5]   8.00-9.00   sec  85.0 MBytes   713 Mbits/sec    0   6.01 MBytes
[  5]   9.00-10.00  sec  85.0 MBytes   713 Mbits/sec    0   6.01 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec   836 MBytes   701 Mbits/sec    0             sender
[  5]   0.00-10.04  sec   835 MBytes   698 Mbits/sec                  receiver

Test run #3

edi@****:~$ iperf3 -c *.*.*.* -p 5201 -t 10
Connecting to host *.*.*.*, port 5201
[  5] local 10.1.0.4 port 54568 connected to *.*.*.* port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  66.8 MBytes   560 Mbits/sec    0   6.06 MBytes
[  5]   1.00-2.00   sec  85.0 MBytes   713 Mbits/sec    0   6.06 MBytes
[  5]   2.00-3.00   sec  85.0 MBytes   713 Mbits/sec    0   6.06 MBytes
[  5]   3.00-4.00   sec  83.8 MBytes   703 Mbits/sec    0   6.06 MBytes
[  5]   4.00-5.00   sec  85.0 MBytes   713 Mbits/sec    0   6.06 MBytes
[  5]   5.00-6.00   sec  83.8 MBytes   703 Mbits/sec    0   6.06 MBytes
[  5]   6.00-7.00   sec  85.0 MBytes   713 Mbits/sec    0   6.06 MBytes
[  5]   7.00-8.00   sec  83.8 MBytes   703 Mbits/sec    0   6.06 MBytes
[  5]   8.00-9.00   sec  83.8 MBytes   703 Mbits/sec    0   6.06 MBytes
[  5]   9.00-10.00  sec  85.0 MBytes   713 Mbits/sec    0   6.06 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec   827 MBytes   694 Mbits/sec    0             sender
[  5]   0.00-10.04  sec   827 MBytes   690 Mbits/sec                  receiver

Average: 702 Mbps

Conclusion

1. As for 2/25/2023, the network speed for B1s VMs between a few datacenters in Azure China and Azure Global are listed below.
2. Azure does not provide an official bandwidth limit information for B1s, it seems to be 1Gbps.
3. The fastest connection is between China East 2 in Azure China and East Asia in Azure Global.