[NTLUG:Discuss] ADSL Configuration Questions

[Richard Cobbe]

Dan Carlson wrote on 2-24-2000:

> I am in the process of getting an ADSL line from GTE with DirectLink as the
> ISP.  I have received the hardware package from GTE and the configuration
> info email from DirectLink.  GTE is not scheduled to turn service on until
> 3/9.

They *are* slow, aren't they?  I had similar problems last September.

>From what I understand, this is largely GTE's fault; I must say that
DirectLink had almost inhuman patience with me.  I called to pester them
about this roughly daily until GTE finally scheduled a time.

I'm reminded of a line spoken by, I believe, Lily Tomlin, in the movie
_9 To 5_:

"We don't care.  We don't have to.  We're the phone company."

> I am trying to understand as much of the configuration process as I can in
> advance so that I can get up and running as quickly as possible once GTE
> turns service on.
> 
> I run Linux on the internet server / gateway for my home network.  While I
> am not an expert, I am reasonably experienced at configuring Linux networks,
> interfaces, routing, etc.  If I were an expert, I wouldn't have to ask these
> questions! :)

Actually, I think you'll be surprised and impressed how easy the process
is.  It took me all of about 10 minutes, although I've got a simpler
network setup.

<SNIP DETAILS>

There's really not much configuration you have to do.  On the router that
does masquerading, you'll need to set your default route to use the gateway
address that DirectLink supplies, over the 10baseT network.  I'm not sure,
but I suspect that the DSL modem doesn't have an IP address.  I ought to
find something that allows me to snoop ARP queries and investigate that,
though.

The only other annoying thing is that on this gateway, the 10baseT
adapter's IP address will change to the one assigned by DirectLink, so
you'll have to adjust the gateway for other machines on this subnet and
whatever firewalling/masquerading scripts.  However, since it's a static
IP, this is a one-time thing.  Other than that, you're pretty much set.

You can plug the DSL modem straight into a 10BaseT hub, although see below
regarding cabling issues.

Couple of of notes regarding the GTE install:

1) Save time: have the phone jacks in your place easily accessible before
   the GTE tech gets there.  We had to move a heavily laden bookshelf so he
   could get into the phone jack and adjust the wiring.  I don't remember
   entirely what the situation was, but he actually needed to access all 3
   phone jacks in my apartment.  I seem to recall that he mentioned that
   this was an unusual circumstance.

2) You will likely need to get some additional cabling.  The DSL modem
   comes with a very short phone cord and a very short Ethernet crossover
   cable.  Any phone cord will do, so you can stop by Radio Shack or
   whatever.  If you're going to hook the DSL modem into a hub, you'll
   almost definitely need a straight-through cable rather than a
   crossover.

Oh, yeah, and finding a place to put the modem is annoying.  It's roughly
6" by 8" by 2".  Although it has mounts on the back for you to hang it on
the wall, the large cables and such coming out the back (well, the top when
you hang it) make that look really ugly.

> Separate question: Is there any protocol running above IP over the ADSL
> link, such as PPP?

No.  Or, well, not unless it's completely transparent to the PC.  Barring
IP addresses and NIC device drivers, my network setup at home is exactly
the same as my network setup at work, where I hook into a corporate LAN
that has a T1 (or something) out to the Net.

> Any insight that can be offered into these questions will be appreciated.

Well, I went through this process a few months back, although with a
simpler network setup: I've only got the one PC.  Still, if you have any
more questions, I'll be glad to answer them.

Good luck, and enjoy the bandwidth!

Richard