[OLPC Networking] tcp/ip assumptions

[Oliver Mattos]

There's two issues here:

1.  The services that are running on the XO should be listed somewhere on
the wiki, especially all services that accept incoming network connections
or make connections.

2.  The XO makes connection requests to services that may not exist.  This
may not be a problem in some cases, since the overhead of a failed
connection attempt is very low, and in the case of things like an NTP
request an "occasional" connection still keeps the clock accurate enough for
our purposes.

On Jan 29, 2008 1:56 AM, Mikus Grinbergs <mikus at bga.com> wrote:

> I have a G1G1, which communicates via a local LAN to a "relay"
> system, which communicates to the internet.  The server facilities
> (*just* for the XO - not needed by the "regular" systems on my LAN)
> I've now set up in the "relay" station are minimal (e.g., for DNS).
>  The result is that many XO requests are not fulfilled by my
> "relay" system (for instance, a separate dialog may be needed -
> between the "relay" system and a *real* server out on the internet).
>
> I was looking at a trace of the packets on my local LAN.  In the
> case of DNS, the XO issues three "Type 28" requests (which my
> minimal "relay" station does not support), before issuing a "Type
> 01", to which it eventually does get an answer.  In the case of NTP,
> the XO issues "scattershot" requests to all server addresses it was
> able to extract [but receives no responses, because it tries to
> contact them directly, rather than going through the 'proxy'
> function in my "relay" system].
>
>
> My conclusion:  The tcp/ip function in the XO makes a number of
> assumptions as to the type (and timeliness) of the external SERVICES
> it expects to have been provided.  I would have been happier if I
> had known about these beforehand, rather than having to discover
> what does or does_not work in the environment I currently have.
> [Might some setups in a target country be as minimal as mine?]
>
> mikus
>
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