Question VPN IPsec Tunnel Packet loss on large download files

[lvk36]

Hi,

I'm trying to access a remote power monitoring sensor (Fluke 1775) using a VPN IPsec tunnel. with limited networking knowledge.

However I'm running into a problem: The data files I'm trying to download (~500mB) are unable to be downloaded. Packet sniffing during the transfer shows that a number of packets are either [TCP Previous segment not captured], [TCP Dup ACK],[TCP Fast Retransmission], [TCP previous segment not captured], [TCP out-of-order]. These happen right before the fluke downloading software stops receiving the rest of the data, and just hangs. Smaller files have no issue being downloaded. This is the hardware configuration in use:

Fluke 1775 (1000Base-T) -> (100/1000) Zyxel GS1900 Series Switch (100/1000) -> (10/100) D-Link DWM-312W (LTE Connection, 90% Signal Strength) -> IPSec VPN Tunnel -> Remote computer running Fluke Energy Analyse software to download data.

I have attempted to turn on Flow Control on the switch and router and have reduced the router MTU to 1024. Neither have had any effect.



Any help would be greatly appreciated!

 

[bill001g]

A vpn should not care how big the file is.

Have you tried to copy these files locally just to be sure it is not some application issue.

Is there any particular size it consistently works and then above that it consistently breaks. If it is random I would suspect you are getting data loss. The messages you are seeing are most times caused by packet loss but it can also be application related.

It is a complex configuration even if you have a real point to point vpn when you go though a vpn hosting company it adds a layer of complexity. I assume you are doing that because side with the LTE connection does not have a public IP.

Do you have any ability to let a ping run between the 2 sites that will pass through the vpn. It unfortunately might be load related and only show loss when you are transferring files.

The most common source of packet loss is going to be on the LTE network but you would need to find a way to test that.

In general it takes quite a bit of packet loss to terminate a tcp session. It is using the retransmissions to try to recover the lost data without dropping the session.