old-www/HOWTO/Cable-Modem/prerequisites.html

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NAME="PREREQUISITES"
></A
>2. Prerequisites</H1
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="NETWORKING"
></A
>2.1. Networking and Ethernet Support</H2
><P
>Most, if not all, cable modems are easily configured for use with Linux.
Most cable modems have two possible interfaces for connection to your computer:
Ethernet or USB. If your version of Linux is like most, there is very little you will need to do to to get your cable modem
working with an Ethernet interface as long as you have support for networking and the driver for your specific networking hardware installed.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="NIC"
></A
>2.2. Ethernet Support</H2
><P
>An open Ethernet interface is the most likely means that a cable provider will use or recommend when
setting up your cable internet service. Your ISP may even deliver and/or install a new NIC card to access the modem if you have no open Ethernet cards available.The cable connects to the modem, which then connects to your NIC using ordinary 10BaseT/100BaseT Ethernet cable. If you are uncertain about any of the above, and your modem and/or NIC are not already physically installed for you, read the <A
HREF="http://www.tldp.org/HOWTO/Ethernet-HOWTO.html"
TARGET="_top"
>Ethernet HOWTO</A
> and your
cable modem's instruction manual before proceeding any further.</P
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><P
>Do not try to install an NIC by yourself unless you are already familiar with the process or are assisted by someone who is.</P
></TD
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><P
>For software support, most base installs of Linux distributions come enabled for TCP/IP networking and common Ethernet
hardware drivers 'out of the box,' so if you are using a preconfigured
kernel from a boxed or downloaded version of a Linux distribution you can probably skip to <A
HREF="prerequisites.html#MODEM"
>Section 2.4</A
>. If you don't know what a kernel is and/or are curious about it, see
the <A
HREF="http://www.tldp.org/HOWTO/Kernel-HOWTO.html"
TARGET="_top"
>Kernel HOWTO</A
>
for more information.</P
><P
>The (Linux kernel) networking support requirements for use of a cable modem include the following, and which you will need to select
using whatever kernel configuration front-end application (whether <B
CLASS="COMMAND"
>make config</B
>, <B
CLASS="COMMAND"
>make menuconfig</B
> or <B
CLASS="COMMAND"
>make
xconfig</B
>) prior to compiling a custom kernel. For 2.4.x and earlier kernels under the heading 'Networking options' you will require 'TCP/IP Networking' along with 'Network Device Support,' go to 'Ethernet (10 or 100Mbit) Support' and enable your specific NIC driver. If you use the 2.6.x series, the heading 'Drivers' has a sub-heading 'Networking Support,' where you should enable 'Network Device Support' and 'Ethernet Connection Support/Ethernet (10 or 100Mbit), as well as your specific NIC hardware driver.</P
><P
>If you are interested in how to configure the USB interface go to <A
HREF="prerequisites.html#USBCONFIG"
>Section 2.3</A
>; otherwise you can go to <A
HREF="prerequisites.html#MODEM"
>Section 2.4</A
>.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="USBCONFIG"
></A
>2.3. USB Interface Support</H2
><P
>There seems to be no reliable data regarding testing bandwidth or performance of an Ethernet connection vs. the USB port of cable modems. In theory they should be equivalent, though some believe there is poorer performance (at least in Linux) using USB. Unless you have no way to use an Ethernet interface, have no ability to add a cheap NIC, or are just plain determined, there is probably no advantage to using USB. If so, you will need the following, in addition to Networking support outlined above: 1) USB Subsystem support 2) your host controller driver (UHCI, OHCI or EHCI) and one of the following:</P
><P
>Kernel Version 2.4.x</P
><P
></P
><UL
><LI
><P
> CDC Ethernet Support</P
></LI
></UL
><P
>For kernel 2.6.x you will need </P
><P
></P
><UL
><LI
><P
> Multi-purpose USB Networking Framework (CONFIG_USB_USBNET) with</P
></LI
><LI
><P
>CDC Ethernet support (CONFIG_USB_CDCETHER)</P
></LI
></UL
><P
>See <A
HREF="configuration.html#USB"
>Section 3.3</A
> for instructions on how to load modules when time to test the modem.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="MODEM"
></A
>2.4. The Modem Device</H2
><P
> First, plug in and turn on
the cable modem. Connect your Ethernet card to the modem with 10BaseT/100BaseT cable
into the non-USB interface if this was not already done for you. Be sure the modem
isn't on standby mode or turned off; this should be obvious looking at the LEDs. The
standby button is on the top of the device on most models. Note that your cable internet
provider should be able to tell remotely whether your modem is connected and functioning
properly, which is helpful to differentiate hardware from configuration problems on
your end. They will also need the MAC (Media Access Control) hardware address of your
modem to allow the device access to their network. If at any time you substitute one
modem for another you will need to inform them so the MAC address can be updated and
your access to the cable network restored. </P
><P
> Your modem will be assigned
an IP address once connected for the first time that may remain the same or may change
periodically depending on the IP address turnover of your ISP's DHCP server and how
long you remain offline if you disconnect. </P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="DHCP"
></A
>2.5. The DHCP Client</H2
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="DHCP-DEB"
></A
>2.5.1. Installation on a Debian System</H3
><P
> Debian requires you have a DHCP
client package installed and running. As of this writing there are two user-space
programs for this. In Woody (stable), there is the dhcp-client package, automatically
installed as a part of the base packages as <TT
CLASS="FILENAME"
>/sbin/dhclient</TT
>. For
Sarge (testing) and up, this has been replaced by the dhcpcd package. The latter
has its configuration files under <TT
CLASS="FILENAME"
>/etc/dhcpc</TT
>, but nothing really
needs to be modified if you have only one Ethernet card you will be using for the cable
internet service. The dhcpcd daemon is easily installed for those using testing branch
as root with <B
CLASS="COMMAND"
>apt-get install dhcpcd </B
>. </P
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="DHCP-RPM"
></A
>2.5.2. Installing on .rpm- or .tgz-Based Systems</H3
><P
> For .rpm- or .tgz-based distributions, I offer the following
link that walks you through the setup of a DHCP client, in the <A
HREF="http://www.tldp.org/HOWTO/mini/DHCP/x74.html"
TARGET="_top"
>DHCP mini-HOWTO</A
>. </P
><P
> Just run <B
CLASS="COMMAND"
> /sbin/dhclient </B
> or whichever client you use to
get a dynamic IP address. </P
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