XMG1915-18EP SFP+ to 2.5 Gb clients bad speed

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nielsscheldeman
nielsscheldeman Posts: 40  Freshman Member
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edited May 2 in Switch

I bought for a client a XMG1915 setup, but I have so problems with the speed.

Situation:

Server SFP+ connected to XMG1915 SPF+ port 18
Client with 2.5 Gb/s connected to port 1 RJ45

Writing to the server goes at 280 MB/s
Downloading from the server goes at 120 MB/s

Added a 10Gb SFP+ NIC in that same client: downloading and uploading goes at 1.1 GB/s from and to the server, so fine now! Means also that client and server can handle the speed.

Also added an extra client at 2.5 Gb/s port 2 and I can up and download to both clients at full 280 MB/s(2.5 Gb/s)

Copy from the server to client 1 at 120 MB/s and add a copy to client 2 also gives client 2 also 120 MB/s, so that's in a way fine

So in conclusion: speed from sfp+ ports to rj45 goes inside the switch is bad, it goes at 1 Gb/s(but multiple clients can get 1 Gb/s simultaneously)… Is this setting? Is on latest firmware. Bug in firmware?

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  • Zyxel_Melen
    Zyxel_Melen Posts: 1,714  Zyxel Employee
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    edited May 7
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    Hi @nielsscheldeman,

    Server SFP+ connected to XMG1915 SPF+ port 18
    Client with 2.5 Gb/s connected to port 1 RJ45

    Writing to the server goes at 280 MB/s(2.5Gb/s)
    Downloading from the server goes at 120 MB/s

    I did a local lab that a 2.5G client and 10G SFP+ server connect to XMG1915 with latest firmware and run iperf test. Here's my results:

    image.png

    So, the XMG1915 or its firmware seems not have a transmission issue. Your issue is more likely a High-to-Low Link Transmission. Could you help to enable flow control on the server connecting port to check if the issue been solved? Kindly remind, the server also needs to enable it on its NIC setting. The flow control will help to improve the poor transmit speed by sending pause frame when the packet buffer reaches a threshold.

    Flow control configuration path:
    Menu > Port > Port Setup

    image.png

    Zyxel Melen

  • nielsscheldeman
    nielsscheldeman Posts: 40  Freshman Member
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    edited May 3
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    Ok, it goes better now, but not steady results. When I for example transfer a file of 12 GB now, it goes 280 MB/s, but after 80% it goes down to 75 MB/s. Restarting the test after few minutes still remains at 75 MB/s until I reboot the switch. Copper to Fiber upload always goes fine.

    I see now something else strange. I have a server connected to a Sourcelight RJ45 to SFP+ module(Port 17) and a computer directly on SFP+ (fs module) at port 18. Copying from the computer @ SFP+ goes at 280 MB/s, but after 10 seconds it drops. If I now simultenously start a copy from the server connected to Port 17(which only reaches 80 MB/s), the other copy speed immediately goes up to 190 MB/s so I can fill the full 2.5 Gb/s bandwith with 2 sources.

    As soon as I pause the copie from P17, the other copie also drops in speed.

    Disconnecting P17 or P18 gives no full speed on the other port continuously, so it's not that they are conflicting with eachother.

    Copying from the computer @ 2.5 Gb/s to both 10 Gb/s devices always goes full speed.

  • Zyxel_Melen
    Zyxel_Melen Posts: 1,714  Zyxel Employee
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    Hi @nielsscheldeman,

    Thanks for your feedback. May I know your test-building information? Like your PC & Server's OS, OS version, NIC card, NIC card driver version, etc.
    I would like to compare it with my test building. Also, please help to collect the tech support for me to check the configuration and port counter.

    I ran a 300-second full-speed test with iperf and saw no decrease in speed.

    XMG1915 iperf 300s.png

    My test-building is:
    2.5G PC: Win 11 23H2. Realtek 2.5G NIC card

    10G Server: Win 11 23H2. Zyxel XGN-100C

    Zyxel Melen

  • mparka
    mparka Posts: 10
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    I had the same issue but with XGS1210-12. My solution was to change 10G port to "Flow Control = enabled". It helped.

  • nielsscheldeman
    nielsscheldeman Posts: 40  Freshman Member
    First Anniversary 10 Comments Friend Collector
    edited May 16
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    Server = Intel X520 SFP+ / 2*Intel D3S4520 3.84 TB RAID1 on Adaptec 3101e-4I / Windows Server 2022 VM on Hyper-V Core

    Client1=Intel I225v / Samsung 980 1 TB

    Client2= Intel X520 SFP+ / Samsung 980 1 TB

    —

    Client1 upload to Server : 280 MB/s | Client1 download from server : 120 MB/s

    Client2 upload to Server: 1 GB/s | Client2 download from server: 1 GB/s

    So fiber to fiber goes fine, but as soon as I download from Fiber to copper it goes bad.

    Flow control enabled only on 10G server and also tried flow control enabled on all.

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