Apple airport base station DHCP / DNS problems.

[Chris]

hi everyone,

im using an apple airport base station (v4.0.8), connected to a cable
modem, in its capacity as a router to share internet traffic on my
home network.

the setup is as follows, the airport is connected to the cable modem
via the WAN port, and connected to a hub/switch via the LAN port. a
mac laptop is connected via a wireless airport card, and two pc's are
connected via the switch. the airport is setup to connect via ethernet
using DHCP. it is also set to distribute ip addresses and share a
single ip address (via DHCP and NAT).

this was configured about a week ago and has been running fine without
any problems during that time, but in the process of finalising the
setup i ran into a strange problem.

seeing as the airport had been used to connect to the internet via a
modem in its previous life, i decided to create a new configuration
(using the pc version of the airport admin tool, and specifying the
internet/ethernet setup and network setup mentioned above) to clear
out all the old dial up settings and update the airport with only the
necessary internet / ethernet, network settings (now i realise this
was an unnecessary step, but it seemed like a good idea at the time).

but when i created, imported, and updated the airport with the new
configuration, i noticed that the ethernet connection to the cable
modem no longer appeared to be retrieving DNS settings from my ISP,
and that the airport stopped functioning as a DHCP server. in testing
the new configuration i noted that the internet still seemed to be
working, but all the computers on the internal network were no longer
being assigned ip addresses.

i then imported and restored the previous settings, and everything
returned to normal. i then double checked the new and old
configurations, and aside from the details entered in the modem
sections, they appeared to be exactly the same.

my main question here is, does anyone have any idea what happened
during this process, why these problems occurred, and if i missed
something here that would explain these problems.

my main concern is that i have no idea what caused this problem or
what is going on here at all, im completely in the dark on this one,
as it just seems to make no sense to me at all. and that being the
case i figure that even though the airport seems to be working at the
moment, its quite possible that its faulty, or perhaps not set up
correctly, and that this could cause problems later on down the track.

is it possible that the pc config tool could be responsible for the
problems, i.e. it isn't written as well as its mac equivalent, and
didn't quite implement the updates correctly. or is it possible i
missed an area of configuration that i assumed wasn't important, but
actually is ?

any ideas, suggestions, or answers anyone can give me here would be
greatly appreciated.

thanks,

chris

[Christian]

Chris <chrisr@go.to> wrote:

> im using an apple airport base station (v4.0.8), connected to a cable
> modem, in its capacity as a router to share internet traffic on my
> home network.
> ...
> is it possible that the pc config tool could be responsible for the
> problems, i.e. it isn't written as well as its mac equivalent, and
> didn't quite implement the updates correctly. or is it possible i
> missed an area of configuration that i assumed wasn't important, but
> actually is ?

I don't think so. However it seems you messed up the settings a bit.

1) the cable modem should get the IP address dynamically from the
provider, just as the old dial up modem did.

2) the airport base just gets the official IP address "forwarded" from
the cable modem

3) the airport base needs to "translate" the single IP address to the
local addresses (which it distributes via DHCP). These local addresses
need to be in the private ranges as defined by the "internet
authorities" - 192.168.x.x, 172.16.x.x, or 10.1.x.x.

I don't know if this info helps, but it is always a good thing to know
what should go on.

Christian.

--
Christian F. Buser, Hohle Gasse 6, CH-5507 Mellingen (Switzerland)
Hilfe für Strassenkinder in Ghana: <http://www.chance-for-children.org>

[Chris]

[email]christian030801@rumantsch.ch[/email] (Christian) wrote in message news:<1fzlscx.1ddhx721mvrts0N@christian.rumantsch. ch>...

> Chris <chrisr@go.to> wrote:
>

> > im using an apple airport base station (v4.0.8), connected to a cable
> > modem, in its capacity as a router to share internet traffic on my
> > home network.
> > ...
> > is it possible that the pc config tool could be responsible for the
> > problems, i.e. it isn't written as well as its mac equivalent, and
> > didn't quite implement the updates correctly. or is it possible i
> > missed an area of configuration that i assumed wasn't important, but
> > actually is ?

>
> I don't think so. However it seems you messed up the settings a bit.
>
> 1) the cable modem should get the IP address dynamically from the
> provider, just as the old dial up modem did.
>
> 2) the airport base just gets the official IP address "forwarded" from
> the cable modem
>
> 3) the airport base needs to "translate" the single IP address to the
> local addresses (which it distributes via DHCP). These local addresses
> need to be in the private ranges as defined by the "internet
> authorities" - 192.168.x.x, 172.16.x.x, or 10.1.x.x.
>
> I don't know if this info helps, but it is always a good thing to know
> what should go on.
>
> Christian.

hi christian,

from what i can tell, the cable modem just acts as an interface
between the cable and the network card / port. when i plug it into the
airport, and set the airport to connect via ethernet, its the airport
thats assigned the "real world" ip address, or so it seems. in either
case im reasonably certain the config (connect via ethernet) would be
the same. in addition the airport does assign the local ip addresses
via DHCP (10.0.1.2 - 10.0.1.4, with the airport itself being 10.0.1.1)
and it does route traffic between the "real world" ip and these local
ip's.

the problem im having is that when i import and update the new config
(which is seemingly identical to the old config) the airport stops
assigning local ip addresses (even though its configured to do so) and
appears to cease picking up the DNS server details via DHCP (even
though the DNS still appears to work). its like the process of
updating the airport itself causes a problem. but then again im no
expert.

chris