Manual

Network Device for the eCos TCP/IP Stack

Name

Network Device — USB-ethernet support for the eCos TCP/IP Stack

Description

If the USB peripheral involves running the eCos TCP/IP stack and that stack needs to use USB-ethernet as a

transport layer (or as one of the transports), then the USB-ethernet package can provide a suitable network device

driver. It is still necessary for higher-level code to perform appropriate initialization by calling usbs_eth_init,

but after that it will be the TCP/IP stack rather than application code that transmits or receives ethernet frames.

Not all peripherals involving the USB-ethernet package will require a TCP/IP stack. Hence the provision of the

network device is controlled by a conﬁguration option CYGPKG_USBS_ETHDRV. By default this will be enabled if

the TCP/IP package CYGPKG_NET is loaded, and disabled otherwise.

There are a number of other conﬁguration options related to the network device. CYG-

FUN_USBS_ETHDRV_STATISTICS determines whether or not the package will maintain statistics, mainly intended

for SNMP: by default this will be enabled if the SNMP support package CYGPKG_SNMPAGENT is loaded, and

disabled otherwise. The name of the ethernet device is controlled by CYGDATA_USBS_ETHDRV_NAME, and has a

default value of either eth0 or eth1 depending on whether or not there is another network device driver present

in the conﬁguration.

Usually eCos network device drivers default to using DHCP for obtaining necessary information such as IP ad-

dresses. This is not appropriate for USB-ethernet devices. On the host-side the USB-ethernet network device will

not exist until the USB peripheral has been plugged in and communication has been established. Therefore any

DHCP daemon on the host would not be listening on that network device at the point that eCos requests its IP

and other information. A related issue is that the use of DHCP would imply the presence of a DHCP daemon on

every affected host machine, as opposed to a single daemon (plus backups) for the network as a whole. For these

reasons the USB-ethernet package precludes the use of DHCP as a way of setting the IP address, instead requiring

alternatives such as manual conﬁguration.

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