TCP/IP in Mixed Ethernet and USB networks

www.helmig.comParts of these pages on USB Networking are a cooperation with
Parallel Technologies, the creator/ inventor/ developer
of the DirectParallel® technology licensed to Microsoft
for the Direct Cable Connection (DCC) feature in
Windows 95/98/2000/ME/XP ( supplier of the fast
DirectParallel® cable and of USB connection cables).

You can connect your USB
network of Windows98 or ME,
Windows 2000 and WindowsXP
systems to an Ethernet network,
resulting to a mixed network with
Ethernet and USB network adapters
For Windows XP, there is an
easier, better solution :
Windows XP Network Bridge

The simple setup using the “Bridge Protocol” (on Windows9x/2000) or using a
Network Bridge” (Windows XP only) will enable all systems to share data :

This is the configuration of this network:

The system “C500” has now to act as a router between the different network segments.
The installation of the “Bridge Protocol” allows the communication via NetBEUI.
For a communication via TCP/IP, an advanced setup is now required.
Before continuing, please make sure that you have sufficient knowledge of TCP/IP configurations.
1) Both Windows98/ME and Windows2000 support the Automatic IP-generation, which would
result in this example on the Router (the Windows 2000 system “C500”) to the following
IP-addresses assigned ( report generated by “ipconfig“):

The Automatic IP-generation has assign both IP-addresses of the SAME subnet 169.254.x.x,
but for routing, the IP-addresses need to be on different subnets.

It is now required to configure TCP/IP manually.
I used for my setup the IP-values below:

using the subnet: 192.168.1.x for the Ethernet LAN and 192.168.2.x for the USB LAN:
The “router” system, Ethernet LAN adapter, TCP/IP-properties:
– IP-address:
– Subnet mask:

The “router” system, USB LAN adapter, TCP/IP-properties:
– IP-address:
– Subnet mask:

On the Systems on the
Ethernet LAN
(in this example: NT4WSP120)
(subnet: 192.168.1.x),
I need to define the
Ethernet adapter in the
(at to be
the “Default Gateway“.
On the Systems on the
(subnet: 192.168.2.x),
I need to define the
USB-adapter in the
(at to be
the “Default Gateway

After making the change, test the communication using the TCP/IP PING :

make sure, that from the
Router-system you can
ping” (and get “Reply from..”)
all systems on both
the Ethernet LAN Segment
and the USB-LAN segment.
make sure, that from the systems
on the Ethernet Segment, that you
can “ping” the router-system and
the systems on the USB-LAN.
make sure that from the systems
on the USB Segment, that you
can “ping” the router-system and
the systems on the Ethernet segment.
If you do not get a reply
(“Request timed out“), make
sure that the “Default Gateway
address is properly defined.

And you need to enable on the Router-system the “IP-forwarding”:
Windows 2000

A note on some special configurations:
if one of the systems has a modem and connects to the Internet:

That connection will reset the “Default Gateway” to become the modem, so any connection
to systems on the other network segment will be lost (and systems on the other network segment
will loose the connection with this system).
To avoid that, use the “ROUTE” -command instead of defining the “Default Gateway
(as shown in : TCP/IP and WAN ).

Another possible configuration

If you are using a USB-network to connect your notebook in the office to an PC
connected to the office network and you like to access from your notebook a server
on the Ethernet LAN or a system via the WAN, then you will need the cooperation of
the Network Administrator (lucky, if you are it yourself ! ), because he will need:
– assign to you a subnet to be used for your USB-network (in the example: 192.168.10.x)
– add to the local servers a ROUTE-command, so that the servers know to use the
desktop-system with both the Ethernet and USB adapter (in this example: as
a router to communicate with the notebook.
– if you like to use the WAN, also the systems in the headquarter need to be
configured for the subnet of your USB-LAN segment.

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