Network Connections
This section describes the process of establishing a basic network connection with the board. Once a network connection is established, the system may be accessed through the servers on the board, including SSH, HTTP, FTP, and Telnet.
 Local Area Network
To make a connection to a local area network (LAN), simply connect a standard Ethernet patch cable to the primary Ethernet port on the board. This may be done before or after power has been applied, as the system is set up to allow hot-plugging of the network interface and should automatically re-configure the network settings when a link is detected.
EMAC OE Linux devices are set to attempt a DHCP network configuration by default. If a DHCP server is available on the network that the system is connected to, it will contact the server to secure an IP address lease. If an address has been obtained by DHCP, there are several ways of determining what address has been leased. The easiest way to access this information is to connect to the board through another method (i.e. serial terminal or graphical interface) and run the
ifconfig command to determine the address that has been obtained on the
eth0 interface. Alternatively, network tools such as packet sniffers can be used to determine what IP address has been leased. The local network administration can determine and provide this information as well by querying the DHCP server tables. The listing below illustrates usage of the
ifconfig command to determine the IP address.
eth0 Link encap:Ethernet HWaddr 00:50:C2:E6:60:F4
inet addr:10.0.2.100 Bcast:10.0.255.255 Mask:255.255.0.0
inet6 addr: fe80::5054:ff:feb1:f83e/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1825 errors:0 dropped:0 overruns:0 frame:0
TX packets:553 errors:0 dropped:0 overruns:0 carrier:0
RX bytes:139124 (135.8 KiB) TX bytes:50603 (49.4 KiB)
Interrupt:25 Base address:0xc000
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
If the board fails to obtain a lease from a DHCP server, it will fall back to a static networking configuration. The default settings are detailed in Table 2 below.
|Table 2: Default Static IP Settings|
 Direct Connection
If a LAN connection is not available or desirable, you may make a direct connection to the board. Use an Ethernet crossover cable to connect directly between the workstation and the target board. Apply power to the board once the physical connections have been made.
|Note that most newer networking devices include support for Auto MDI/MDIX, which allows them to detect if the network cable requires a crossover and automatically matches the correct configuration. Auto MDI/MDIX only needs to be supported on one end of the link for this to work. If you are certain that your workstation or target board supports Auto MDI/MDIX, a standard Ethernet patch cable may be used for a direct connection rather than a crossover cable.|
If a direct connection has been made to the board and a DHCP server is not running on the workstation, DHCP will fail and the system will fall back to the default IP settings in Table 2 above. The network interface on the workstation will then need to be configured to use the same subnetwork mask and broadcast address as the target board with a different IP address that falls in the same subnetwork. See Table 3 below for suggested static network settings if the board is still configured with the default static fall back settings. If the configuration has been changed, adjust these values to match the new settings.
|Table 3: Static Network Settings for Direct Connection|
|Default Gateway||Blank or 10.0.2.41|
To verify that the connection is working properly, use the
ping utility to test that the board responds at the address 10.0.2.41 (assuming default network configuration). The listing below shows an example of a successful
ping (Ctrl-c was pressed after five packets).
PING 10.0.2.41 (10.0.2.41) 56(84) bytes of data.
64 bytes from 10.0.2.41: icmp_req=1 ttl=64 time=0.447 ms
64 bytes from 10.0.2.41: icmp_req=2 ttl=64 time=0.213 ms
64 bytes from 10.0.2.41: icmp_req=3 ttl=64 time=0.308 ms
64 bytes from 10.0.2.41: icmp_req=4 ttl=64 time=0.318 ms
64 bytes from 10.0.2.41: icmp_req=5 ttl=64 time=0.251 ms
--- 10.0.2.41 ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 3996ms
rtt min/avg/max/mdev = 0.213/0.307/0.447/0.081 ms
 Next Steps
After you have established a connection with your device running EMAC OE Linux, you will need to log into the system.