How to Share a Cable MODEM
With Windows 98 Second Edition - Preliminary Work
Last updated: 10/11/00
PRELIMINARY WORK. This article builds on two previous
articles written for the Digest and assumes the reader will have reviewed
them and, if need be, will refer to them.
It also assumes:
1. You have an operating Windows 95/98 LAN. Don't
worry about the protocol for now; just be sure it works.
2. You have a PC with Windows 98 SE installed and
it is interfaced to operational external cable MODEM. This PC
will have two Network Interface Cards (NICs) or adapters installed. One
(NIC1 in the diagram above) is for is for the local area network and
the other (NIC2) is for the external CM. (If anyone can figure-out
how to do this with one adapter, I'd appreciate an E-Mail.) The network
equipment in ICS Gateway computer I configured consisted of:
This PC is attached to two networks: the LAN and the Internet
(that cloud depicted above actually lowers (like fog) to include the ICS
gateway PC when the PC is connected to the Internet; i.e., it becomes a host
computer on the Internet like any other computer on the Internet). These
two networks cannot "talk" to each other directly. Again,
ICS becomes a gateway between.
will not work with an Internal, one-way CM, which must rely on a separate
dial-up MODEM and dial-up adapter software for upstream traffic. That
is, ICS cannot "talk" to more than on entity on the Internet
side of the gateway.
An external CM (with an integral dial-up MODEM on a one-way
cable) is connected to a PC with a network card. In this case, ICS
works because it "talks" to a single Internet entity, the network
adapter. The network adapter is actually assigned an Internet IP address
by the ISP's DHCP server acting through the CM. During installation,
ICS assigns a static IP address (192.168.0.1) to the network adapter on the
LAN and after installation the ICS DHCP component assigns/leases additional
IP addresses to client computers on the LAN (192.168.0.2, 192.168.0.3, etc.). One
NIC is on the Internet, the other is on the LAN, and ICS is the go between.
IP addresses 192.168.0.XXX are block of 256 class
C network numbers which the Internet Assigned Numbers Authority (IANA)
reserved for private internets per RFC 1918 (Address Allocation for Private
Internets) they used with 255.255.255.0 subnet mask (more Greek, huh?). These
addresses may not be used directly on the Internet.
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