首先抱歉我的英語，我希望你能理解我。
我有一個 Ubuntu 11.04 盒子。有一個透過 USB 插入的電纜數據機 (motorola sbg900)。我的頻寬應該是 8Mbps 下載和 0.7Mbps 上傳。前一段時間一切都運作得很好，但在過去的幾周里我的下載速度無法超過 400-450kB/s。今天仔細查看了一下，發現是USB連線的問題。我嘗試透過 RJ45 連接到調製解調器，最大下載速度為 8Mbps（良好）。我回到 USB，速度不超過 400-450kB/s（即 4mbits）。
我不知道出了什麼問題。我無法使用 RJ45 - 我必須使用 USB 連接到電纜數據機。
請幫忙..
$ 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
$ 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