When using one host as the Internet gateway, you will need 2 network
devices. One would be an Ethernet network card for you intranet. The
other can be an Ethernet card going to a DLS/cable modem or a modem to
dial-out. You will using the ICS host as a gateway. That requires two
network interfaces.
Of course, when using a host as an Internet gateway, it must be left
powered up all the time so all the other hosts on your intranet can make
a connect through your ICS host. If the ICS host is powered down,
hangs, or some other problem occurs that interferes with either network
interface then everyone on the intranet has lost Internet access. A
DSL/cable router is a much better solution. It consumes far less power
than an entire computer left running, it is more reliable than using
Windows, and they often come with a built-in switch so you don't need a
separate one. You might want to get a small UPS to use for the router
or use the UPS you have for your computer, but if you don't use any
UPSes on your computers then there's no point in just keeping the router
up by itself.
The DSL/cable router probably has NAT (network address translation)
unless you get an old one. This lets the router look like a computer
because it gets assigned the IP address from your ISP's server (just
like your own computer would). Some ISPs still will not allow home
networking and you must buy another IP allocation from them. If you
have 5 home PCs then you have to pay extra to get 4 more DHCP-assigned
IPs from them. Otherwise, only one host at a time could use the ISP
since that's the only IP address that has been currently assigned by
their DHCP server to accept for connections on your account with them.
The NAT router gets one DHCP-assigned IP address from them so all the
ISP ever sees is just the one "computer" on your account. The NAT
router then becomes your DHCP server from which you get IP assignments
to your intranet hosts. If you have more hosts on your network than
there are ports available on the router, you can use the switch
downstream of one of the ports to give you more ports to connect hosts
(basically you build a tree of switches). Although NAT routers will
usually allow its DHCP server to allocate 100 IP addresses or more, most
of those sold for home-use will only handle the traffic for about 15
hosts after which the processor within the NAT router cannot keep up
with the speed necessary to switch amongst all the concurrent
connections through it for local and outbound connections.
Regardless of using a DSL/cable router or just using a hub or switch to
the DSL/cable modem, a switch is still much better than a hub. A hub
present a single signal backplane which will result in more contentions
between hosts. A switch dedicates a signal path to each connection and
results in less contention. That's why switches cost more than hubs.
Switches have a processor. Hubs don't. See
http://snurl.com/hub_vs_switch for some info regarding hubs versus
switches.
If you use one of your computers as a gateway with 2 network interfaces
and ICS then you have that host connected to the DSL/cable modem (for a
NIC) or a telephone line (for modem dial-up) and your intranet is on the
other network interface in that ICS host. If you only have 2 computers,
there's no need for a switch; just connect the NIC in the downstream
host to the NIC in your ICS host. If you have 3 or more hosts then you
would connect the switch to the intranet NIC on your ICS host and attach
your intranet hosts to the switch. If you instead get a NAT router, it
connects to your DSL/cable modem and probably has 4 or more ports to
which you connect your intranet hosts. If you have more hosts than the
number of downstream or intranet ports on the NAT router then use the
switch.
I don't know what is implied by the "Auto switching" in the product's
name of "Auto switching Ethernet switch". Sounds redundant to me. A
switch is always automatic. A switch is always switching (well, I
suppose, not if only one host is attached on its downstream side).
Either it is a switching hub (aka switch) or it is a passive or
repeating hub (repeating hubs, also called active hubs, regenerate the
signal by cleaning it up and boosting it so they require power).