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Thread: Cable modem on USB, limited speed ?

  1. #1
    Join Date
    Jan 2010
    Beans
    15

    Question Cable modem on USB, limited speed ?

    Hello,

    At first sorry for my english, I hope you will understand me.

    I have a Ubuntu 11.04 box. There is a cable modem (motorola sbg900) plugged in via USB. My bandwidth should be 8mbit download and 0,7mbit upload. Some time ago everything worked just fine, but for last couple of weeks I couldnt download faster than 400-450kB/s. Today I took a closer look at this and it seems that USB connection is the problem. I tried connecting to the modem via RJ45, and max download speed was 8mbit (good). I went back to USB and nothing more than 400-450kB/s (so 4mbits).

    I have no idea whats wrong. I cant use RJ45 - I have to use USB connection to the cable modem.

    Please help..

    Code:
    $ uname -a
    Linux NAS 2.6.38-10-generic #46-Ubuntu SMP Tue Jun 28 15:05:41 UTC 2011 i686 i686 i386 GNU/Linux
    Code:
    $ sudo lsusb -v -s 004:004
    
    Bus 004 Device 004: ID 07b2:0900 Motorola BCS, Inc. SURFboard Gateway
    Device Descriptor:
      bLength                18
      bDescriptorType         1
      bcdUSB               1.10
      bDeviceClass            2 Communications
      bDeviceSubClass         0 
      bDeviceProtocol         0 
      bMaxPacketSize0        32
      idVendor           0x07b2 Motorola BCS, Inc.
      idProduct          0x0900 SURFboard Gateway
      bcdDevice            1.01
      iManufacturer           1 Motorola Corporation
      iProduct                2 USB Cable Modem
      iSerial                 3 XXXXXXXXXXXX
      bNumConfigurations      1
      Configuration Descriptor:
        bLength                 9
        bDescriptorType         2
        wTotalLength           80
        bNumInterfaces          2
        bConfigurationValue     1
        iConfiguration          4 USB Ethernet Configuration
        bmAttributes         0xc0
          Self Powered
        MaxPower              100mA
        ** UNRECOGNIZED:  05 24 00 10 01
        ** UNRECOGNIZED:  05 24 06 00 01
        ** UNRECOGNIZED:  0d 24 0f 03 00 00 00 00 ea 05 00 00 00
        Interface Descriptor:
          bLength                 9
          bDescriptorType         4
          bInterfaceNumber        0
          bAlternateSetting       0
          bNumEndpoints           1
          bInterfaceClass         2 Communications
          bInterfaceSubClass      6 Ethernet Networking
          bInterfaceProtocol      0 
          iInterface              5 Communication Interface Class
          Endpoint Descriptor:
            bLength                 7
            bDescriptorType         5
            bEndpointAddress     0x85  EP 5 IN
            bmAttributes            3
              Transfer Type            Interrupt
              Synch Type               None
              Usage Type               Data
            wMaxPacketSize     0x0008  1x 8 bytes
            bInterval              64
        Interface Descriptor:
          bLength                 9
          bDescriptorType         4
          bInterfaceNumber        1
          bAlternateSetting       0
          bNumEndpoints           0
          bInterfaceClass        10 CDC Data
          bInterfaceSubClass      0 Unused
          bInterfaceProtocol      0 
          iInterface              6 Data Interface Class
        Interface Descriptor:
          bLength                 9
          bDescriptorType         4
          bInterfaceNumber        1
          bAlternateSetting       1
          bNumEndpoints           2
          bInterfaceClass        10 CDC Data
          bInterfaceSubClass      0 Unused
          bInterfaceProtocol      0 
          iInterface              6 Data Interface Class
          Endpoint Descriptor:
            bLength                 7
            bDescriptorType         5
            bEndpointAddress     0x81  EP 1 IN
            bmAttributes            2
              Transfer Type            Bulk
              Synch Type               None
              Usage Type               Data
            wMaxPacketSize     0x0040  1x 64 bytes
            bInterval               0
          Endpoint Descriptor:
            bLength                 7
            bDescriptorType         5
            bEndpointAddress     0x02  EP 2 OUT
            bmAttributes            2
              Transfer Type            Bulk
              Synch Type               None
              Usage Type               Data
            wMaxPacketSize     0x0040  1x 64 bytes
            bInterval               0
    Device Status:     0x0001
      Self Powered

  2. #2
    Join Date
    Feb 2008
    Beans
    5,078
    Distro
    Xubuntu 16.04 Xenial Xerus

    Re: Cable modem on USB, limited speed ?

    That's the speed of USB 2.0. If you want faster, use RJ45.

  3. #3
    Join Date
    Jan 2010
    Beans
    15

    Re: Cable modem on USB, limited speed ?

    Quote Originally Posted by gordintoronto View Post
    That's the speed of USB 2.0. If you want faster, use RJ45.
    According to Wikipedia USB 2.0 has maximum bandwidth of 480 Mbit/s (60 MB/s). I have 450kB/s (so about 4Mbit/s).

  4. #4
    Join Date
    Jan 2010
    Beans
    15

    Re: Cable modem on USB, limited speed ?

    Here is output from "hwinfo" for USB port where cable modem is plugged in:
    Code:
      usb device: name = 4-1:1.0
        path = /devices/pci0000:00/0000:00:06.0/usb4/4-1/4-1:1.0
        modalias = "usb:v07B2p0900d0101dc02dsc00dp00ic02isc06ip00"
        bInterfaceNumber = 0
        bInterfaceClass = 2
        bInterfaceSubClass = 6
        bInterfaceProtocol = 0
        if: 4-1:1.0 @ /devices/pci0000:00/0000:00:06.0/usb4/4-1
        bDeviceClass = 2
        bDeviceSubClass = 0
        bDeviceProtocol = 0
        idVendor = 0x07b2
        idProduct = 0x0900
        manufacturer = "Motorola Corporation"
        product = "USB Cable Modem"
        serial = "00XXXXXXXXXXX"
        bcdDevice = 0101
        speed = "12"
    I assume that "speed = 12" means, that USB (1.1) is working in "Full Speed" (12 Mbit/s). That could be true: Motorola SBG900 supports only USB 1.1. Other USB devices connected with this computer have "speed = 480" (USB 2.0 Hi-speed). So it seems that the problem is somewhere else... Does anyone have any ideas ? ;(

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