Slow download from Europe via classic HTTP load balancer

[pmadr]

Hello,

I'm observing strange slowdown of downloaded content via GCE global HTTP load balancer (classic). Please do you have some recommendations?

Observations:

1. Download to machine located in USA - fast (approx. 30MB/s)
2. Download to machine located in Europe - slow (approx. 40KB/s)
3. I have tried to create a new balancer (not classic) and the download is fast from any location. So it seems to me as an issue with the classic balancer.

4. The download speed very differs according to time, e.g. morning run is always faster than afternoon.

5. The deeper analyze shows many (approx. 8000) TCP ZeroWindow packets ! It can mean the Google balancer machine is overloaded. Please Google, look at this issue.

If someone from Google team wants to inspect it, the project name is stage-1301.

[pmadr]

Note: today at 7 am UTC the download takes 9 seconds, now at 10 am UTC the download takes 123 seconds.

Can it have some relation between USA to Europe overall network traffic?