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snack

Member

From: Italy

Registered: 2009-01-13

Posts: 893

Slow ethernet via USB-C adapter

Hi, I have two USB-C adapters, both with an ethernet port. One is from Dell while the other from Startech; both seem to ship the same hardware, as lsusb reports for both:

$ lsusb
Bus 004 Device 003: ID 0bda:8153 Realtek Semiconductor Corp. RTL8153 Gigabit Ethernet Adapter

Also ethtool reports similar information. For the Dell:

Settings for eth0:
        Supported ports: [ TP MII ]
        Supported link modes:   10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
                                1000baseT/Half 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: Symmetric Receive-only
        Advertised auto-negotiation: Yes
        Advertised FEC modes: Not reported
        Link partner advertised link modes:  10baseT/Half 10baseT/Full 
                                             100baseT/Half 100baseT/Full 
        Link partner advertised pause frame use: Symmetric
        Link partner advertised auto-negotiation: Yes
        Link partner advertised FEC modes: Not reported
        Speed: 100Mb/s
        Duplex: Full
        Port: MII
        PHYAD: 32
        Transceiver: internal
        Auto-negotiation: on
        Current message level: 0x00007fff (32767)
                               drv probe link timer ifdown ifup rx_err tx_err tx_queued intr tx_done rx_status pktdata hw wol
        Link detected: yes

For the Startech:

Settings for eth0:
        Supported ports: [ TP MII ]
        Supported link modes:   10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
                                1000baseT/Half 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: Symmetric Receive-only
        Advertised auto-negotiation: Yes
        Advertised FEC modes: Not reported
        Link partner advertised link modes:  10baseT/Half 10baseT/Full 
                                             100baseT/Half 100baseT/Full 
        Link partner advertised pause frame use: Symmetric
        Link partner advertised auto-negotiation: Yes
        Link partner advertised FEC modes: Not reported
        Speed: 100Mb/s
        Duplex: Full
        Port: MII
        PHYAD: 32
        Transceiver: internal
        Auto-negotiation: on
        Current message level: 0x00007fff (32767)
                               drv probe link timer ifdown ifup rx_err tx_err tx_queued intr tx_done rx_status pktdata hw wol
        Link detected: yes

However, the effective speeds are much different. For example, this is what I get when refreshing the pacman database using the Dell:

$ sudo pacman -Syy
:: Synchronizing package databases...
 repo-ck                   41.8 KiB   174K/s 00:00 [############] 100%
 core                     135.0 KiB  2.20M/s 00:00 [############] 100%
 extra                   1692.9 KiB  5.51M/s 00:00 [############] 100%
 community                  4.8 MiB  4.74M/s 00:01 [############] 100

and this is with the Startech:

$ sudo pacman -Syy
:: Synchronizing package databases...
 repo-ck                   41.8 KiB   167K/s 00:00 [############] 100%
 core                     135.0 KiB  1038K/s 00:00 [############] 100%
 extra                   1692.9 KiB   996K/s 00:02 [############] 100%
 community                  4.8 MiB   995K/s 00:05 [############] 100%

I tried many times and the numbers are reproducible. I also tried to disconnect any other device (e.g. HDMI) from the adapter leaving only the ethernet cable plugged, but I got the same results. So at this point I'm a bit clueless, and I'd need some guidance to continue troubleshooting the problem. Thanks.

seth

Member

From: Won't reply 2 private help req

Registered: 2012-09-03

Posts: 76,116

Re: Slow ethernet via USB-C adapter

I'd look at the USB side of things (lsusb -t), this looks suspiciously capped at 1M/s, ie. USB 1.x style…

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snack

Member

From: Italy

Registered: 2009-01-13

Posts: 893

Re: Slow ethernet via USB-C adapter

@seth: thanks for the reply. My laptop has just one USB-C port, so I attach both adapters to the same port alternately. No daisy chains. So from the laptop hardware point of view there's no difference. Her is what lsusb -t reports for Dell:

/:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 10000M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/4p, 5000M
        |__ Port 4: Dev 3, If 0, Class=Vendor Specific Class, Driver=r8152, 5000M

and for Startech:

/:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 10000M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/4p, 5000M
        |__ Port 4: Dev 3, If 0, Class=Vendor Specific Class, Driver=r8152, 5000M

I extracted only the relevant portion of the output (that for Bus 04, Port 4, Device 3 since according to lsusb the etherent adapter is Bus 004 Device 003; I hope I made no mistake here since I dont understand USB numebring scheme very well). The output is identical for the two adapters, so I'd guess that there's nothing wrong under this aspect. Correct?

Mr.Elendig

#archlinux@freenode channel op

From: The intertubes

Registered: 2004-11-07

Posts: 4,097

Re: Slow ethernet via USB-C adapter

Can you test netperf/iperf etc? And test on the same usb port, and ethernet hooked up to the same port on the other end.

Last edited by Mr.Elendig (2019-01-24 11:21:16)

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snack

Member

From: Italy

Registered: 2009-01-13

Posts: 893

Re: Slow ethernet via USB-C adapter

@Mr.Elendig: I did a netperf test as you suggested (same USB port on the laptop, same ethernet cable, same endpoint on my switch). I used another PC on the internal network of my institute as server. Here are the results for Dell:

# netperf -H 172.16.250.247 -p 16604 -l 100
MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 172.16.250.247 () port 0 AF_INET : demo
Recv   Send    Send                          
Socket Socket  Message  Elapsed              
Size   Size    Size     Time     Throughput  
bytes  bytes   bytes    secs.    10^6bits/sec  

131072  16384  16384    100.10     93.95

and for Startech:

# netperf -H 172.16.250.247 -p 16604 -l 100
MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 172.16.250.247 () port 0 AF_INET : demo
Recv   Send    Send                          
Socket Socket  Message  Elapsed              
Size   Size    Size     Time     Throughput  
bytes  bytes   bytes    secs.    10^6bits/sec  

131072  16384  16384    100.16     93.92

Same result for both adapters at the expected rate of 100 MB/s. So I did the pacman -Syy test again and the Startech adapter resulted to be again much slower than the Dell. This makes me think that the problem might be in some router connecting to the external network, which for some reason slows down the traffic coming from the IP address of the Startech. I'll investigate this possibility with IT people and report back. Thanks for now.

progandy

Member

Registered: 2012-05-17

Posts: 5,318

Re: Slow ethernet via USB-C adapter

Same result for both adapters at the expected rate of 100 MB/s. So I did the pacman -Syy test again and the Startech adapter resulted to be again much slower than the Dell. This makes me think that the problem might be in some router connecting to the external network, which for some reason slows down the traffic coming from the IP address of the Startech. I'll investigate this possibility with IT people and report back. Thanks for now.

You could try to use a static IP and/or change the mac address to the one from the Dell. https://wiki.archlinux.org/index.php/MA … s_spoofing

Maybe there is some daily limit for outgoing traffic and you hit it with the Startech connection?

Last edited by progandy (2019-01-24 14:21:14)

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snack

Member

From: Italy

Registered: 2009-01-13

Posts: 893

Re: Slow ethernet via USB-C adapter

I changed the MAC address of the Startech adapter to the one of the Dell adapter, and now the Startech goes as fast as the Dell. According to IT people this could mean that a NAT is slowing down the Startech, but they don't know if it's due to NAT misconfiguration or some bad configuration from my side. Anyway I'll continue investigating with them, thanks to everybody for the support.