OLPC does end run around IP addresses

[C. Scott Ananian]

On Sat, Jan 9, 2010 at 1:35 AM, Mikus Grinbergs <mikus at bga.com> wrote:
> I don't have wireless - my XOs are on ethernet (using interface eth1).
> Currently I am running without a DNS server - meaning that I need to
> issue explicit commands at each XO to set its eth1 IP address.
>
> Just now I've been testing with a deliberately non-customized XO-1 -- I
> have NOT issued any commands to it to set its IP address.  It is running
> build 802B1, and has by default set IP addresses of 169.254... for its
> eth0 and msh0 interfaces (its ethernet eth1 interface has only a default
> IPv6 address).  Netstat at that XO shows only the 169.254 routes.
>
> The other XOs on the ethernet have IPv4 IP addresses only on eth1, in
> the 192.168.1.. range.  They have no IPv4 addresses for their radios.
> Netstat at those XOs shows only the 168.192.1 route.
>
>
> What I find interesting is that Neighborhood View at every XO shows
> *all* other XOs (plus their names) physically attached to the ethernet.
>  'olpc-xos' shows the non-customized XO with its eth0 (radio) IP
> address;  the other XOs are shown with their eth1 (ethernet) IP addresses.
>
> My conclusion:  The XOs are recognizing each other over the ethernet,
> despite having "non-pingable" IP address identities activated.

The 169.x.x.x subnet is reserved for link-local addresses, which is
what these are.  They are pingable from the local link.  It's all
standards-compliant and kosher, be not afraid.
   http://en.wikipedia.org/wiki/Link-local_address
 --scott

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