Frequently Asked Questions

Here you will find answers to typical questions we've had from prospective and current customers. If you still have questions about what Belcarra is and does, please contact us at info@belcarra.com .
 [See also http://usblan.belcarra.com/p/faq.html]

Q - What is meant by driver signing?

A:".... 64-bit versions of Windows Vista and later versions of Windows specifies that a kernel-mode driver must be signed for the driver to load...."  [link to Microsoft Driver Signing policy].

Windows Update demo driver screen shot
Driver signing is a digital signature verifying the software publisher.  If you have ever tried installing a driver or almost any software in a recent version of Windows, you likely have seen a dialog box popup with the name of the company or person that published it.

ALL distributed Belcarra driver kits, development (beta) and production builds, are digitally signed. For description and more information on Belcarra's comprehensive testing and software certification program follow this link 

Q - What is the difference between a USB Host and USB Device?

A. Universal Serial Bus (USB) is not like an Ethernet connection. In an Ethernet network all end-points are the same and can both initiate and receive connection requests.

In a USB system, only the host can initiate a connection. The Devices are in fact slaves to the Host as master - only speaking when spoken to, and unable to "listen in" to conversations happening with other Devices on the link at other times.

A single USB Host may be connected to up to 127 Devices via a cascade of USB hubs up to 6 levels deep. The only time that a USB Device actually "demands" a host notice it is when it first connects to a hub, when a process called "enumeration" happens and the host assigns the Device an ID number for the period it remains connected. The Host also notes when Devices are disconnected from the link. USB Devices may be connected/disconnected at any time without requiring the systems be rebooted or otherwise notified - this is "Hot Swapping" - although some programmatic uses of the devices may object or cause errors if a device is disconnected in the middle of for example a file transfer without notification.
Devices cannot interrupt each other but instead must wait for the host to finish other conversations and poll to see if the Device has traffic available.
The nature of this division betwen Host and Device is recognized in the typical cable - the host "A" end being wider than it is high compared to the more nearly square shape of the device "B" end.
The extension to the original USB specification called USB On-the-go (USBOTG) allows for a host to become a device and vice versa, but at any given time there is only one host on the link, and in a situation where the host and device swap roles, there can only be one device on the link. The initial role of host/device is determined by which end of the cable is plugged into which unit. Thereafter the switching, if allowed, is done under program control. The typical USBOTG smart device has a socket which will accept either end of the USBOTG cable. An example of this use might be 2 PDAs connecting to each other to share data, as opposed to a PDA (usually a Device) connecting to a desktop PC (usually a Host)

Q - Should we request Belcarra's built-in DHCP for our driver?

A . The built-in DHCP server is suitable for PAN (personal area network) devices. This applies to all peripherals EXCEPT infrastructure devices, i.e. peripherals explicitly designed to provide access to a remote network, such as a satellite connection. Such networks will have their own management machinery and will not want Belcarra's built-in DHCP server.
  • PAN device (most cases): enable built-in DHCP server 
  • Infrastructure device (network access device): disable built-in DHCP server
Q - How does this relate to protocol selection?

A. Belcarra's supports ALL common networking protocols including: CDC-ECM, CDC-EEM, CDC-NCM, and RNDIS.

Belcarra by default enables the built-in DHCP service for the CDC-EEM and BLAN protocols, but not for the CDC-NCM and CDC-ECM protocols. However, upon request, the DHCP can be enabled for any protocol.
For more information, please refer to Networking Over USB Protocol Comparisons