Raspberry Pi A, Руководство пользователя, Страница: 86 / 314

P A R T I
C O N N E C T I N G T H E B O A R D
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❍
Bcast— The broadcast address for the network to which the Pi is connected. Any traffic
sent to this address will be received by every device on the network.
❍
Mask—
The network mask , which controls the maximum size of the network to which
the Pi is connected. For most home users, this will read 255.255.255.0.
❍
MTU— The maximum transmission unit size, which is how big a single packet of data
can be before the system needs to split it into multiple packets.
❍
RX
—This section provides feedback on the received network traffic, including the
number of errors and dropped packets recorded. If you start to see errors appearing in
this section, there’s something wrong with the network.
❍
TX—
This provides the same information as the RX section, but for transmitted pack-
ets. Again, any errors recorded here indicate a problem with the network.
❍
collisions— If two systems on the network try to talk at the same time, you get a colli-
sion which requires them to retransmit their packets. Small numbers of collisions
aren’t a problem, but a large number here indicates a network issue.
❍
txqueuelen— The length of the transmission queue , which will usually be set to 1000
and rarely needs changing.
❍
RX bytes, TX bytes—
A summary of the amount of traffic the network interface has
passed.
If you’re having problems with the network on the Pi, you should first try to disable and then
re-enable the network interface. The easiest way to do this is with two tools called
ifup
and
ifdown
.
If the network is up, but not working correctly—for example, if
ifconfig
doesn’t list any-
thing in the
inet addr
section—start by disabling the network port. From the terminal,
type the following command:
sudo ifdown eth0
Once the network is disabled, make sure that the cable is inserted tightly at both ends, and
that whatever network device the Pi is connected to (hub, switch or router) is powered on
and working. Then bring the interface back up again with the following command:
sudo ifup eth0