Routers and TCP/IP Networking
is a multiport connectivity device that directs nodes on a network.
Basically, when a router receives an incoming packet, it reads the packet’s
network address and subnet mask
and determines to which network the packet
should be delivered.
A router’s strength lies in its intelligence. Not only can routers keep track of the
locations of certain nodes on the network, but they can also determine the
shortest path between two node
They can do the following:
Connect dissimilar networks.
Interpret Layer 3 addressing and other information (such as quality of
Determine the best path for data to follow from point A to point B.
Reroute traffic if a primary path is
down but another path is available.
is a technique in which a network administrator programs
a router to use specific paths between node.
Static routing does not take into account for occasional network
connections, or device moves.
Moving a device of part of the network causes the network
administrator to reprogram the router.
automatically calculates the best path between two
nodes and accumulates this information in a routing table.
If congestion of failures affect the network, a router using
dynamic routing can detect the problems and reroute data
through a different path.
When a router is added to a network, the routing table is updated.
refers to the most efficient
route from one node on a
network to another. Some routers determine best path by fewest number
of hops. Others use complex mathematical algorithms.
For a PC to access the Internet, it must have the TCP/IP protocol loaded (p. 378).
/IP is so popular that even non
Internet accessible Internets are using it (p.
In Windows 98/ME, you configure TCP/IP though
Windows 200/XP, you configure TCP/IP in
My Network Places
a command that ena
bles one machine to check whether it can
communicate with another machine (p. 384).
a tool in Windows 9X/ME that displays the TCP/IP settings and
information (p. 384).
a tool in Windows NT/2000/XP that displays the TCP/IP settings and
information (p. 384).
a tool that shows the route data takes to reach its destination (p. 385).
Private Network Addresses
There is a standard reserved block of addresses for use in private networks.
These are networks that will never be conne
cted directly to any other public
The private networking standard is shown below:
Routers on the Internet are designed not
to “route” private network addresses. If
a router encounters a data packet destined for a private network, it simply drops
it. This is the reason why private network addresses are also called “non
In short, the basic purpose of priva
te networks is to allow companies to establish
LANs without the cost or bother of acquiring public IP addresses.
A computer that wants to send data to another machine outside its local area
network cannot know all the IP addresses on th
e Internet (p. 382).
Instead, all IP addresses know the name of one computer, to which they pass all
the data they need to send outside the LAN (p. 383).
This machine is called the default gateway, and it is usually the local router (p.