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Thread: Asymmetric speeds on 1Gb ethernet network - why?

  1. #1
    Join Date
    Apr 2014
    Beans
    8

    Question Asymmetric speeds on 1Gb ethernet network - why?

    I have an Ubuntu Linux machine and an iMac Pro. Ubuntu is 19.04 x64. Fast i5-7600K and 16GB of RAM, NVMe SSD etc. Both are connected with Cat 5e to an Ubiquiti switch. Why am I getting asymmetric results in iperf? I get the same with iperf3 and also if I change window size to bigger values:

    Code:
    ------------------------------------------------------------
    Server listening on TCP port 5001
    TCP window size: 1.00 MByte (WARNING: requested  512 KByte)
    ------------------------------------------------------------
    ------------------------------------------------------------
    Client connecting to 192.168.0.30, TCP port 5001
    TCP window size: 1.00 MByte (WARNING: requested  512 KByte)
    ------------------------------------------------------------
    [  5] local 192.168.0.10 port 58770 connected with 192.168.0.30 port 5001
    [ ID] Interval       Transfer     Bandwidth
    [  5]  0.0-10.0 sec   881 MBytes   739 Mbits/sec
    [  4] local 192.168.0.10 port 5001 connected with 192.168.0.30 port 60297
    [  4]  0.0-10.0 sec  1.09 GBytes   934 Mbits/sec
    There is a 200Mbps discrepancy. Why?

    When I do the same test between a MacBook Pro and the iMac Pro over wired I get symmetric speeds of 940Mbps.

    The ethernet adapter on Linux:

    Code:
    Settings for enp0s31f6:
            Supported ports: [ TP ]
            Supported link modes:   10baseT/Half 10baseT/Full
                                    100baseT/Half 100baseT/Full
                                    1000baseT/Full
            Supported pause frame use: No
            Supports auto-negotiation: Yes
            Supported FEC modes: Not reported
            Advertised link modes:  10baseT/Half 10baseT/Full
                                    100baseT/Half 100baseT/Full
                                    1000baseT/Full
            Advertised pause frame use: No
            Advertised auto-negotiation: Yes
            Advertised FEC modes: Not reported
            Speed: 1000Mb/s
            Duplex: Full
            Port: Twisted Pair
            PHYAD: 2
            Transceiver: internal
            Auto-negotiation: on
            MDI-X: on (auto)
            Supports Wake-on: pumbg
            Wake-on: g
            Current message level: 0x00000007 (7)
                                   drv probe link
            Link detected: yes
    Edit: UDP seems to work more symmetrical:

    Code:
    ------------------------------------------------------------
    Server listening on UDP port 5001
    Binding to local address 192.168.0.10
    Receiving 1470 byte datagrams
    UDP buffer size:  208 KByte (default)
    ------------------------------------------------------------
    ------------------------------------------------------------
    Client connecting to 192.168.0.30, UDP port 5001
    Binding to local address 192.168.0.10
    Sending 1470 byte datagrams, IPG target: 1.18 us (kalman adjust)
    UDP buffer size:  208 KByte (default)
    ------------------------------------------------------------
    [  4] local 192.168.0.10 port 42164 connected with 192.168.0.30 port 5001
    [ ID] Interval       Transfer     Bandwidth
    [  4]  0.0-10.0 sec  1.11 GBytes   952 Mbits/sec
    [  4] Sent 809725 datagrams
    [  4] Server Report:
    [  4]  0.0-10.0 sec  1.11 GBytes   952 Mbits/sec  64786.432 ms 2145864389/2146673923 (1e+02%)
    [  4] 0.00-10.00 sec  1 datagrams received out-of-order
    [  3] local 192.168.0.10 port 5001 connected with 192.168.0.30 port 53980
    [  3]  0.0-10.2 sec  1.11 GBytes   927 Mbits/sec  13.666 ms 2145476882/2146284995 (1e+02%)
    Last edited by Waldo_Nell; 1 Week Ago at 11:35 PM.

  2. #2
    Join Date
    Apr 2014
    Beans
    8

    Re: Asymmetric speeds on 1Gb ethernet network - why?

    I might have just solved it. I found this thread, tried disabling tso and gso offloading:

    Code:
    ethtool -K enp0s31f6 tso off gso off
    Did a test again:
    Code:
    ------------------------------------------------------------
    Server listening on TCP port 5001
    Binding to local address 192.168.0.10
    TCP window size:  250 KByte (WARNING: requested  125 KByte)
    ------------------------------------------------------------
    ------------------------------------------------------------
    Client connecting to 192.168.0.30, TCP port 5001
    Binding to local address 192.168.0.10
    TCP window size:  250 KByte (WARNING: requested  125 KByte)
    ------------------------------------------------------------
    [  5] local 192.168.0.10 port 36989 connected with 192.168.0.30 port 5001
    [ ID] Interval       Transfer     Bandwidth
    [  5]  0.0-10.0 sec  1.08 GBytes   931 Mbits/sec
    [  4] local 192.168.0.10 port 5001 connected with 192.168.0.30 port 53768
    [  4]  0.0-10.0 sec  1.08 GBytes   928 Mbits/sec

  3. #3
    Join Date
    Aug 2011
    Location
    Berlin, Germany
    Beans
    7,685
    Distro
    Ubuntu Mate 16.04 Xenial Xerus

    Re: Asymmetric speeds on 1Gb ethernet network - why?

    What hardware is it?
    Code:
    lspci -nnk | grep -iA2 net
    lsmod
    ifconfig -a

  4. #4
    Join Date
    Apr 2014
    Beans
    8

    Re: Asymmetric speeds on 1Gb ethernet network - why?

    Code:
    00:1f.6 Ethernet controller [0200]: Intel Corporation Ethernet Connection (2) I219-V [8086:15b8]
            Subsystem: ASRock Incorporation Ethernet Connection (2) I219-V [1849:15b8]
            Kernel driver in use: e1000e
            Kernel modules: e1000e
    Code:
    e1000e                245760  0
    Code:
    enp0s31f6: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 192.168.0.24  netmask 255.255.255.0  broadcast 192.168.0.255
            inet6 fe80::7285:c2ff:fe3a:ae18  prefixlen 64  scopeid 0x20<link>
            ether 70:85:c2:3a:a2:18  txqueuelen 1000  (Ethernet)
            RX packets 10542930  bytes 9915138005 (9.9 GB)
            RX errors 0  dropped 331  overruns 0  frame 0
            TX packets 13614376  bytes 19449638563 (19.4 GB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
            device interrupt 16  memory 0xdc200000-dc220000

  5. #5
    Join Date
    Aug 2011
    Location
    Berlin, Germany
    Beans
    7,685
    Distro
    Ubuntu Mate 16.04 Xenial Xerus

    Re: Asymmetric speeds on 1Gb ethernet network - why?

    Code:
    enp0s31f6: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 192.168.0.24  netmask 255.255.255.0  broadcast 192.168.0.255
            inet6 fe80::7285:c2ff:fe3a:ae18  prefixlen 64  scopeid 0x20<link>
            ether 70:85:c2:3a:a2:18  txqueuelen 1000  (Ethernet)
            RX packets 10542930  bytes 9915138005 (9.9 GB)
            RX errors 0  dropped 331  overruns 0  frame 0
            TX packets 13614376  bytes 19449638563 (19.4 GB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
            device interrupt 16  memory 0xdc200000-dc220000
    Check the mtu value of your ISP and the nameserver resolution

  6. #6
    Join Date
    Apr 2014
    Beans
    8

    Re: Asymmetric speeds on 1Gb ethernet network - why?

    What does my ISP have to do with this? My issue is with local LAN speed. I do not use Jumbo frames on the LAN. Nameserver has nothing to do with this as I am performing a speed test using IP addresses.

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