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One way throughput problem

asked 2024-09-21 19:30:31 +0000

quazi gravatar image

updated 2024-09-21 21:38:14 +0000

Chuckc gravatar image
Connectivity:
Host A ----- Switch ----- Router ----- Router ----- Switch ----- Host B
IP:
Host A: 10.10.10.1
Host B: 10.10.10.2

Host A and B are connected through Router and Switch over an EVPN VPWS tunnel. When transferring data from Host B to Host A, not getting throughput more than 20 Mbps in a single session. However, when transferring data in the opposite direction from Host A to Host B, getting 97 Mbps in a single session. There is no packet loss between Routers. Need help to troubleshoot one way throughput issue.

Capture for file transfer from Host B to Host A:
Host A: https://drive.google.com/file/d/1l1yr...
Host B: https://drive.google.com/file/d/1zBp-...

Capture for file transfer from Host A to Host B:
Host A: https://drive.google.com/file/d/1tlt3...
Host B: https://drive.google.com/file/d/1aBDv...

Thank You.

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Comments

Those capture files (B>-A files > 200MB; A->B files > 600 MB) are kinda big for analysis.
Can you describe the "transferring data" (protocol, application, type of data) to give some insight to how the files might be pared down.

"Upload_from_10.10.10.2-Capture_from_10.10.10.1.pcapng (241M) is too large for Google to scan for viruses. Would you still like to download this file?"

Chuckc gravatar imageChuckc ( 2024-09-21 21:43:57 +0000 )edit

Good day Chuckc.

File transferred over HTTP (TCP, Port 80) using HTTPFileServer.

For the file transfer from Host B > Host A, I noticed a very high number of tcp.analysis.flags on both sides, but at Host A it is higher (55%) than at Host B (27%). At Host A, TCP Out-of-Order is also relatively high.

However, tcp.analysis.flags for the file transfer session from Host A > Host B are 7% and 2%.

Suspecting Tx path issue from Host B > Host A. Need guidance to identify the actual point of failure and the root cause.

quazi gravatar imagequazi ( 2024-09-22 03:45:59 +0000 )edit

hi

If you plug in Host C in to the same switch where Host A is connected are you able to reproduce the problem? can you do the same test but this time connect Host C to the switch where Host B is connected.

Also can you use iperf for your thruput test and post the results?

net_tech gravatar imagenet_tech ( 2024-09-22 18:56:06 +0000 )edit

Upload_from_10.10.10.2-Capture_from_10.10.10.2.pcapng - 3 way handshake isn't captured

Looks like this is the HTTP server OP is using - > https://sourceforge.net/projects/hfs/...

net_tech gravatar imagenet_tech ( 2024-09-22 20:54:51 +0000 )edit

Hi @net_tech Trying to share the result of the suggested environment using Host C at both side and iperf.

Yes, HFS HTTTP file server used for throughput test.

quazi gravatar imagequazi ( 2024-09-23 08:44:30 +0000 )edit

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answered 2024-09-23 13:37:35 +0000

SYN-bit gravatar image

From a quick glance on the pcap files, I suspect the following:

  • There is quite a bit of packet reordering of the data packets from 10.10.10.2 (Host B) to 10.10.10.1 (Host A).
  • The reordered result in DUP-ACKs
  • Due to the amount of reordering, there are tripple DUP-ACKs, resulting in fast-retranmissions
  • The congestion window will be kept low when there are retransmissions, assuming there was packet-loss due to congestion

Are you able to capture on the WAN (EVPN) side of the routers?

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Asked: 2024-09-21 19:30:31 +0000

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Last updated: 1 hour ago