Connecting
a workstation to the network
Each
network topology is associated with a network technology or protocol. Ethernet
networking is the most common on a bus topology, and Token Ring is the most
common on a ring structure.
The
network technology in use is important because when you connect a PC to the
network for the first time, you need to know the network identity requirements
for a new workstation.
Addressing
the network
The
three addressing elements used on a network that you should know are
l MAC (media access control) address: Every
NIC or network adapter is assigned a unique-tothe-world ID (called the MAC
address) by its manufacturer when it is made. This address is burned into its
firmware and cannot be changed. The MAC address is the basis for all network addressing
and all other address types are cross-referenced to it. A MAC address is a
48-bit address that is expressed as 12 hexadecimal digits (4 bits to a hex
digit). WINIPCFG command display showing the MAC address (Adapter address) of a
NIC, which in this case is 44-45-53-54-00-00.
Tip
To display this box on a Windows PC, enter WINIPCFG in the Start
Run box.
l Remember IP (Internet protocol) address: Many
internal and all external networks use IP addresses to identify nodes on both
LANs and WANs. An IP address for a network workstation combines the address of
the network and the node into a 32-bit address that is expressed in four 8- bit
octets (which means sets of eight). Figure 22-3 shows
the results of the IPCONFIG command that displays the IP addressing information
for a workstation. To run this command, open a command prompt and enter
IPCONFIG on the command line.
The
IPCONFIG command is used to display the IP address configuration of a PC.
IPCONFIG
displays the IP address assigned to the workstation (in this case,
192.168.1.100), its subnet mask (which is used to determine which part of the
network the workstation is located), and the default gateway of the node.
l Network names: The most common form of a
network name is the share name assigned to a workstation and is used to
identify it to other network users who want to share its resources over the
LAN. The most common network name used on a Windows network is the NetBIOS (Network
Basis Input/Output System) name, which is a unique 15-character name that is periodically
broadcasted over the network so that the Network Neighbor-hood function can catalog
them. The NetBIOS name is the one that shows up on the Windows Network Neighborhood.
Addressing
protocols and services
Many
protocols and services can be used on a network to aid in the correlation and
translation of one address form to another.
The ones
you need to know for the A+ exam are the following:
l DHCP (Dynamic Host Configuration Protocol): This
is a protocol used to automatically configure a network workstation with its IP
address data. Each time the workstation is logged on to the network, the DHCP
server software, running on a network server or router, assigns or renews the
IP configuration of the workstation. Typically, the address assigned is from
blocks of IP addresses that have been set aside for use by internal networks.
Depending on the network operating system, IPCONFIG or WINIPCFG can be used to
view, renew, or release DHCP data.
l DNS (Domain Name System): DNS is used to resolve
(translate) Internet names to their IP address equivalents. For example, when
you request www.hungryminds.com from your browser's location
line, a nearby DNS server (typically at your ISP), converts it to an IP
address, such as 12.168.1.100, which is then used to request the data across
the Internet.
l WINS (Windows Internet Naming Service): WINS
is Microsoft's network name resolution software that converts NetBIOS names to
IP addresses. Windows machines are assigned NetBIOS names (see "Addressing
the network" earlier in this section), which are converted into IP addresses
for use on a network using TCP/IP (Transmission Control Protocol/ Internet
Protocol), the foundation protocol suite of the Internet. The use of a WINS
server allows nodes on one LAN segment to find nodes on other LAN segments by
name.
Connecting
to an Ethernet network
When
a new workstation is added to an Ethernet network, it identifies itself using
its MAC address and computer name to the rest of the network. Those devices
that need to hold this addressing information, such as a switch or bridge,
store it in their MAC address tables. When requests come in for a particular IP
address, the MAC address of the node is looked up and the message is sent to
that workstation.
Before
you bury me in e-mails, please understand that this is highly simplified, but
represents the essence of what happens.
Connecting
to a Token Ring network
When
you add a new node to a Token Ring network, it must establish first that its
address is unique. The workstation sends out test frames with its ID address
and the system responds with its own test frames sent to that address. If no
other node responds (oops), the new ID address is accepted and established for the
new ring node. If there is duplication (it can happen), jumpers or DIP switches
on the NIC can be used to alter the address.
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