Re: direct ISDN connection

[George Karaolides <george@karaolides.com>]

On Tue, 5 Feb 2002, Vegh Karoly wrote:

> I'd like to set up an ISDN connection, in case the net-connection would be
> unreachable.
> I mean direct, because the two computers are far away from eachother, and
> we really need a fallback connection.
> I would like to be able to dial in to the other ISDN computer, but found
> only HOWTOs explaining how to set up connection with ISPs.
>
> What do i need for this, how to set up a dial in ISDN server?
> Documentation URLs are also welcome, or which HOWTO shall I read?
>

Hi,

You have two choices:

1. Raw IP over ISDN (rawip).  It looks very much like an ethernet
interface.

2. Synchronous PPP over ISDN (syncppp).  You usually use this to connect
to your ISP over ISDN, so most HOWTO's only cover setting up the "calling"
side of this.  You can also set up the "answering" side.

Which one you choose depends on your needs.  If you are to network two
computers which are both under your control, then I suggest you use rawip
for the folllowing reasons:

- Simpler configuration.

- Faster connection without the PPP authentication overhead.  In fact, the
computers will "feel" almost as if they're on the same LAN.

- Ample security is provided by the isdnctrl "phone-in" and "secure"
features; you only need allow incoming connections from the one phone
number on the other side.

- Easier and more efficient channel bundling (slave channels).  The slave
channels for rawip only dial out when the data rate on the master channel
exceeds a presettable level for a presettable time interval.  For syncppp,
they are always up unless you use the ibod software to control them, and
this provides much less control.

IMHO you only need to set up syncppp dial-in if you're to allow users to
connect with user-based authentication from sites not under your control.

Here we use rawip for WAN connections (three sites) and syncppp for the
connection to our ISP.  If you like, I can tar up my scripts and send them
to you.  You can use them to set up any number of rawip and syncppp
interfaces.  They may look a bit complex, but they're quite flexible.

Best regards,

|      George Karaolides       8, Costakis Pantelides St.,         |
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