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 firstname.lastname@example.org .
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.
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
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