Hi!
We're experiencing issues with inbound network speed that's only about one-tenth of the outgoing speed, and this happens across all types of virtual machines.
We've run iperf3 tests with different Linux distros and firewall appliances, and the results are the same for all of them. Below is the test result from a performance test using an external 500 Mbps fiber connection in the same GCE zone where the virtual machines are running:
Changing the number of vCPUs doesn't seem to matter, nor does the interface type or network tier (whether standard or premium). MTU settings also have no impact.
Have we run into an unknown/hidden soft cap that's throttling inbound traffic?
Any insights on where the bottleneck might be and how to troubleshoot network issues on Google Cloud are all welcome!
Test Configuration:
- Machine type: e2-highcpu-4
- Network tier: premium
- Interface type: gVNIC
Test resuls:
# Inbound (GCP VM <= External test server)
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-1.00 sec 8.50 MBytes 8697 KBytes/sec 23 42.0 KBytes
[ 5] 1.00-2.00 sec 5.25 MBytes 5367 KBytes/sec 16 49.2 KBytes
[ 5] 2.00-3.00 sec 5.62 MBytes 5768 KBytes/sec 17 28.8 KBytes
[ 5] 3.00-4.00 sec 4.50 MBytes 4612 KBytes/sec 13 45.6 KBytes
[ 5] 4.00-5.00 sec 7.50 MBytes 7673 KBytes/sec 9 66.0 KBytes
[ 5] 5.00-6.00 sec 7.50 MBytes 7655 KBytes/sec 5 92.3 KBytes
[ 5] 6.00-7.00 sec 5.38 MBytes 5522 KBytes/sec 22 22.8 KBytes
[ 5] 7.00-8.00 sec 3.50 MBytes 3584 KBytes/sec 18 33.6 KBytes
[ 5] 8.00-9.00 sec 6.38 MBytes 6528 KBytes/sec 6 39.6 KBytes
[ 5] 9.00-10.00 sec 5.75 MBytes 5887 KBytes/sec 9 54.0 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 59.9 MBytes 6130 KBytes/sec 138 sender
[ 5] 0.00-10.04 sec 59.6 MBytes 6077 KBytes/sec receiver
# Outbound (GCP VM => External test server)
[ ID] Interval Transfer Bitrate
[ 5] 0.00-1.00 sec 55.2 MBytes 56518 KBytes/sec
[ 5] 1.00-2.00 sec 55.2 MBytes 56575 KBytes/sec
[ 5] 2.00-3.00 sec 55.5 MBytes 56889 KBytes/sec
[ 5] 3.00-4.00 sec 55.1 MBytes 56412 KBytes/sec
[ 5] 4.00-5.00 sec 55.6 MBytes 56876 KBytes/sec
[ 5] 5.00-6.00 sec 55.6 MBytes 57067 KBytes/sec
[ 5] 6.00-7.00 sec 55.6 MBytes 56969 KBytes/sec
[ 5] 7.00-8.00 sec 55.4 MBytes 56673 KBytes/sec
[ 5] 8.00-9.00 sec 55.5 MBytes 56856 KBytes/sec
[ 5] 9.00-10.00 sec 55.5 MBytes 56811 KBytes/sec
- - - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.04 sec 558 MBytes 56886 KBytes/sec 596 sender
[ 5] 0.00-10.00 sec 554 MBytes 56765 KBytes/sec receiver
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