Using DCC and DUN at the same time

by Johannes Helmig [Published on 15 Aug. 2001 / Last Updated on 15 Aug. 2001]

Direct Cable Connection (DCC) and Dialup-Networking (DUN) are closely
related, and are partially usingthe same software modules (PPPMAC.VXD).
When Microsoft limited the Windows95 Dialup-Networking to a single connection, they at the same time made it impossible to use DCC and DUN at the same time:

BUT on later versions (including Windows 95 Dial-up Networking v. 1.2,
Windows 98, Windows ME) the Dial-up networking can run simultaneously with a
Direct Cable connection.

Once Windows95 has established
a Direct Cable Connection
(either acting as Host or as Client),
it is not possible to dialout via
the Modem to establish another
connection, and it even tells us
properly the reason ("that there is
already a
in use")
DCC connecting as Client:
Dialup Networking is limited to
a single simultaneous connection
And if we first connect via the
modem, and then set up the system
as DCC Host, it seems to be ok,
but it does NOT accept any
incoming DCC connection
(and does not give any error message)
When connecting first via the Modem
and then trying to establish a
connection via DCC(as DCC Client),it does NOT connect
(although the DCC host is properly
configured and waiting for a connection).

The story is different on later version of Dialup-Networking:

with DUN 1.2 Upgrade installed:
as delivered
as delivered
for the Implementation of
Virtual Private Networks (VPN),
it is required to have 2 connections
(first an Internet connection,
second the VPN connection

For this reason, Windows95 with
DUN 1.2 upgrade
and Windows98
can be configured with 2 Dialup-
Networking adapters, allowing now
to have 2 connections at the same time.
I have use NetBEUI as protocol
in this example:

you can act as DCC host and still
are able to dial out
Or being already a DCC Client,
you can establish a second Client
connection using Dialup-Networking
Or being already connected as
a Dialup-Networking Client,
then start up DCC to act as a host
and accept incoming DCC connections.

And while being connected as Client
via Dialup-Networking (using FIND/
Computer to locate resources), make
a second connection as DCC Client,
using View Host to view the resources

Use DCC to share a Dialup-Networking Internet Connection

You like to use DCC to connect 2 computers, to share 1 modem for an Internet connection via Dialup-Networking ?

Although Microsoft has include in Windows98SE / ME and in Windows 2000 the
Internet Connection Sharing (ICS), it will not work when using a DCC connection between
the 2 systems ( the Microsoft ICS is designed for use with networking via LAN).

Using a Non-Microsoft Internet Connection Sharing solution (like: WinRouteLite) and with
some basic knowledge on TCP/IP , you can share the Internet connection using DCC.

See Also

The Author — Johannes Helmig

Dr.Johannes Helmig is working as Director, Technical Knowledge Management in the Belgium office of Gerber Technology where he is involved in Customer Service and internal training, with special interest in Networking.


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