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Troubleshoot slow TCP Throughput in L2MPLS Link

Hi, We have a 155 mbps L2MPLS link from a service provider and distance is <100 kms with a steady latency of 5 ms. The service provider is using WAN Killer UDP traffic pump on both ends and 155 mbps is passing properly and declaring it as successful delivery. But when I am using any applications like FTP or Browser to transfer files between two locations (using TCP) the speed is stuck between 30-45 mbps max. Even after several (>15) simultaneous downloads the speed fluctuates between 90-105 mbps. The network diagram is attached - View I did some google search and found that window size could be a factor but not sure for such a low latency link it would be a problem. Is there any possible options from the service provider end (like increase buffer size) to get the resolution of the problem? We used to have a same link from different provider previously and I saw 140 up and 145 down FTP transfers between LAN to LAN PCs. Any help is really appreciated.

Troubleshoot slow TCP Throughput in L2MPLS Link

Hi, We have a 155 mbps L2MPLS link from a service provider and distance is <100 kms with a steady latency of 5 ms. The service provider is using WAN Killer UDP traffic pump on both ends and 155 mbps is passing properly and declaring it as successful delivery. But when I am using any applications like FTP or Browser to transfer files between two locations (using TCP) the speed is stuck between 30-45 mbps max. Even after several (>15) simultaneous downloads the speed fluctuates between 90-105 mbps. The network diagram is attached - View I did some google search and found that window size could be a factor but not sure for such a low latency link it would be a problem. Is there any possible options from the service provider end (like increase buffer size) to get the resolution of the problem? We used to have a same link from different provider previously and I saw 140 up and 145 down FTP transfers between LAN to LAN PCs. Any help is really appreciated.

PCAP Files (FTP RX & TX)

https://www.dropbox.com/sh/oe2yuowpnipvi4n/AAAL23gtry-jSGbXepJSSdb1a?dl=0