Problems configuring /etc/network/interfaces

[Charles Bray <charles@oshoville.com>]

Hi,

I'm fairly new to Linux and just switched from SuSE to Debian
2.2.19pre17 a few days ago.  I have a Dell Inspiron 7000 notebook.  I've
tried very hard to solve this problem on my own, but the solution
continues to escape me.

Right now, my /etc/network/interfaces file includes the following lines
(excluding comments):

auto lo
iface lo inet loopback

My understanding is that the "auto lo" line is supposed to activate the
loopback interface at boot time.  But evidently it doesn't.  After I
boot and log in as root, if I ping the localhost at 127.0.0.1, I get the
error message:

neighbor table overflow

At this point, the routing table (route -n command) doesn't list the
loopback interface, and I must manually activate and add it with the
lines:

ifconfig lo 127.0.0.1
route add 127.0.0.1 lo

After doing this, I no longer receive the overflow error and can ping
the localhost.

Strangely (to me), if I comment out the "auto lo" line in
/etc/network/interfaces and reboot, I can then successfully ping the
loopback address, indicating that the interface has been automatically
activated.  (So "auto lo" is evidently shutting it down.  I wish I could
find more thorough instructions for configuring
/etc/network/interfaces.)  Although the interface has been activated
automatically, I still have to add it to the routing table using the
above route command.  But, of course, I don't want to have to add the
route manually every time I reboot.

All of the above was learned while I was trying to figure out my
original problem, which is this:

After successfully connecting to my ISP via serial modem (and after
manually adding the loopback interface), the routing table is as
follows:

Destination      Gateway     Genmask      Flags Metric  Ref Use Iface
286.115.220.139  0.0.0.0  255.255.255.255   UH     0     0   0   ppp0
127.0.0.1        0.0.0.0  255.255.255.255   UH     0     0   0   lo
192.168.1.0      0.0.0.0  255.255.255.0     U      0     0   0   eth0
0.0.0.0      192.168.1.1  0.0.0.0           UG     0     0   0   eth0

I can ping 286.115.220.139 as well as my machine's local network IP
address at 192.168.1.1, but I can't ping my ISP's DNS servers or
anywhere else on the internet.

So, for several days I've basically been trying to figure out how to
connect to the internet.  I only have a bare minimum installation and
desperately need to add more functionality via apt-get downloads.  I
tried to follow the installation instructions exactly, but now I'm stuck
and feeling helpless.

Sincere thanks for any suggestions,
Charles