[Testing] Actions: OLPC QA Call with Sri Lanka's Professional Volunteers
wmb at laptop.org
Tue Mar 9 11:33:45 EST 2010
Mikus Grinbergs wrote:
>> 7. Holt will SHIP 12 USB-to-Ethernet dongles from Boston to Sri Lanka.
> I have extensive experience at using Ethernet. Please don't hesitate to
> ask me if you have questions.
> In the meantime, some things to keep in mind:
> * The XOs expect a name server to be available on that Ethernet (to
> give out dynamic IPv4 addresses). The Ethernet ought to also have an
> NTP server on it.
Nomenclature problem: Dynamic IPv4 addresses are given out by a DHCP
a name server. Name servers (also known as "DNS servers") translate
textual names like
"dev.laptop.org" into numeric IP addresses; they have nothing at all to
do with the assignment
of dynamic IPv4 addresses.
The symptom of a DHCP server problem is that machine cannot obtain an IP
itself - attempts to "bring up" the network interface will pause for a
long time and
eventually time out. The symptom of a name server problem is that the
the interface has already been brought up successfully, does not
recognize the names
of machines on the outside Internet - you get messages like "unknown
host" from commands
In some networks, the DHCP server program and the name server program
be running on the same machine - a computer or a router box. But that
is not at all
necessary; they could be running on different machines in wildly
The DHCP server must be local - on the same Ethernet to as Mikus puts it
- so your
machine can reach it by broadcasting, but the name server may be halfway
around the world.
> [I myself have not yet tried running the Ethernet with IPv6 addresses.]
> * When you first install any XO (or first-boot any new build on that
> XO), do it without having the dongle plugged in at the XO. You can plug
> the Ethernet connection in once you see any Sugar screen.
> What this does is assign the Ethernet device *after* the radio device
> has been assigned. It turns out Ethernet control does not work well if
> 'eth0' had been assigned to the Ethernet device. [ You can check that
> Ethernet is on 'eth1' in /etc/udev/rules.d/70-persistent-net.rules ]
> It helps if you keep the SAME Ethernet dongle with each individual XO.
> Each time you use a different dongle, Network Manager assigns a
> different interface name -- that can quickly get confusing.
> * The Network Manager could randomly step in and assign a zeroconf IP
> address to a working Ethernet interface (thereby taking the previously
> existing connection down).
> I actually wrote a tiny batch script that I invoke manually. It issues
> the 'ifconfig' and 'route' commands to re-establish Ethernet connection.
> * If you boot and Ethernet is not working, issue 'ifconfig' and look
> for the (usually 'eth1') interface assigned to the Ethernet. Network
> Manager is what assigns that interface - so it needs to be running. A
> good way to "kick" the Ethernet connection into life (when the XO is
> running but the Ethernet isn't) is to unplug the Ethernet cable from the
> dongle, wait five or more seconds, then plug the cable back in again.
> * Attempts to assign a static IPv4 Ethernet address to an XO
> may/may_not work. Tread carefully.
> * Treat the Ethernet icon in Frame more as an indicator than as a
> control over the Ethernet connection itself. Instead: to start
> Ethernet, plug in the cable; to stop Ethernet, pull out the cable.
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