Transcript Chapter 1 - Introduction to Networking Concept

Introduction to
Networking Concepts
Lesson 1
TCP/IP Protocol Suite
• Network protocols provide the logical “language”
for communication over the network.
• The most common networking protocol in use
today is Transmission Control Protocol/Internet
Protocol (TCP/IP).
IP Addressing
• For any computer or host to communicate on a TCP/IP
network, it must be configured with a valid IP address.
• Each IP address consists of two components:
– network address — This portion of the IP address is shared
by all TCP/IP hosts on a particular network or subnet.
– host address — This comprises the portion of the IP address
that is unique to a particular computer or host.
• Both combined form a unique IP address across an entire
TCP/IP network.
IP Addressing
• In addition to the IP address, each TCP/IP host must be
configured with the following:
– subnet mask — Used to identify which network the TCP/IP
host resides on by defining where the network address
stops and the host address begins.
– default gateway — Allows a host to communicate with
devices that reside on a remote network or location.
• You don’t need a default gateway if it is does not need to
communicate outside of the host’s own subnet.
IPv4 Addressing
IPv4 Addressing
• The most commonly used version used today.
• Based on 32-bits (four bytes, or octets).
• 232 (4,294,967,296) possible addresses.
• Some of the possible addresses are reserved
• IPv4 addresses are commonly represented using what is
called dotted-decimal notation, in which the decimal value of
each byte is shown, using periods to separate the bytes:
10.27.3.1
192.1.120.84
192.5.18.102
 00001010. 00011011. 00000011. 00000001
 11000000. 00000001. 01111000. 01010100
 11000000. 00000101. 00010010. 01100110
Classful Addressing
• The field for the network number was a different
length for different classes of network, and the
remaining bits were used for the host number.
• Each network class had a different maximum
number of nodes.
• The first one to four bits identified the network
class, and the remaining bits comprised the
network and host address fields.
Classful Addressing
Class A Networks
• Had the most significant bit as “0” and used the
remainder of the first octet for the network
number.
• There were 126 Class A networks, with a
maximum of 16,777,214 hosts in each.
• Note that the number of valid networks and hosts
available is always 2N – 2
(where N is the number of bits used and the 2
adjusts for the special function of the first and last
address in each network).
Class B Network
• Class B networks had the two most significant bits
as “10,” with the remainder of the first two octets,
or fourteen bits, representing the network
number.
• There were 16,384 Class B networks, with a
maximum of 65,534 hosts in each.
Class C Networks
• Class C networks had the three most significant
bits as “110,” with the remainder of the first three
octets as the network number and the last octet
as the host number.
• There were 2,097,152 Class C networks, each with
a maximum of 254 host addresses.
Classful Addressing Examples
• 15.234.48.34
– Default subnet mask is 255.0.0.0
– Network address is 15.0.0.0
– Host address is 0.234.48.34
• 203.23.47.234
– Default subnet mask is 255.255.255.0
– Network address is 203.23.47.0
– Host address is 0.0.0.234
Class D and Class E Networks
• Network addresses with the four most significant
bits “1110” (Class D, multicast).
– Multicast addressing is used to deliver to multiple host
simultaneously using the most efficient strategy to
deliver the messages over each link of the network
only once, creating copies only when the links to the
multiple destinations split.
• “1111” (Class E, reserved) were also defined.
Classless Inter-Domain Routing (CIDR)
• When classful network addresses started became scarce,
public Internet Service Providers (ISPs) started to allocate
many small networks to their customers.
• Breaks the network address space into CIDR blocks
• The number of masked bits is specified with the CIDR
notation.
• Example:
– 10.0.0.0/8 would describe 8 bits masked and 24 bits for
host numbering.
Classless Addressing Examples
• 15.234.48.34/24
– Subnet mask is 255.255.255.0
– Network address is 15.234.48.0
– Host address is 0.0.0.34
• 203.23.47.234/16
– Subnet mask is 255.255.0.0
– Network address is 203.23.0.0
– Host address is 0.0.47.234
Subnetting
• Logical partitioning of an organization’s network
address range into smaller blocks.
Subnetting Example
• Network Address (Enteprise/corporation): 16.52.0.0/16
– Default Subnet mask is 255.255.0.0
• Site 1 has network address of:
16.52.1.0
– With subnetting, the subnet mask becomes 255.255.255.0
• Site 2 has network address of:
16.52.2.0
– With subnetting, the subnet mask becomes 255.255.255.0
Private Addresses
• For convenience, several network address blocks
were reserved for private networks.
• Defined as non-routable outside of the private
network.
Network Address Translation (NAT)
• Hosts using private network addresses can
communicate with public networks only by using
network address translation (NAT),
• Enables routing by mapping their private network
address to a different, routable network address.
Loopback Address
• Specifies itself at address 127.0.0.1
IPv6 Addressing
• Near exhaustion of the 4-billion-plus IP addresses
available through IPv4.
• While the use of private IP networks and NAT
have alleviated the problem somewhat, a longterm solution is still required.
• IPv6, the next generation of the TCP/IP protocol,
was developed to provide a significantly larger
address space for current and future
implementations of TCP/IP networks.
IPv6 Addressing
• IPv6 uses 128 bits, or 16 bytes, for addressing.
– Providing 2128 (about 340 billion) unique addresses.
• Uses eight groups of four hexadecimal digits,
separated by colons.
• IPv6 includes a few other enhancements for
performance and security.
– IPSec.
IPv6 Addressing
• IPv6 addresses are 128 bits in length and expressed in
hexadecimal notation. For example,
– 2001:0db8:85a3:08d3:1319:8a2e:0370:7334
• If an IPv6 address contains a series of sequential zeroes,
the address can be shortened to use a single zero in each
group, or else the entire grouping can be represented
using a double colon (::).
– 2001:0000:0000:0000:0000:0000:0000:7334
– 2001:0:0:0:0:0:0:7334
– 2001::7334
IPv6 Addressing
• IPv6 networks can be expressed using CIDR
notation such as 2001:0db8:1234::/48 to
represent the 2001:0db8:1234 network
configured with a 48-bit subnet mask.
Domain Name System (DNS)
• Domain Name System (DNS) used for name
resolution.
• It translates from Host name to IP addresses.
• HOSTS files also translate from Host name to IP
addresses.
• Prevents you from remembering addresses.
– Instead, remember meaningful logical names.
Domain Name System (DNS)
Traditional Top-Level Domain Names
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.com – Commercial
.edu – Education
.gov – Agencies of U.S. federal government
.net – Computers of network providers and ISPs
.org – nongovernmental and nonprofit
organizations
Fully Qualified Domain Name (FQDN)
• Describes the exact relationship between a host
and its DNS domain.
• Example:
computer1.sales.adatum.com
– Host name is computer1
– In the sales domain, which is in the adatum secondlevel domain, which is in the .com top-level domain,
which is under the “.” root domain.
Dynamic Host Configuration Protocol
(DHCP)
• Simplifies the problem of static IP address by
automating the assigning, tracking, and
reassigning of IP addresses.
• Also to provide other important settings such as
the default gateway, subnet mask, DNS, and so
on.
DHCP Relay Agent
• DHCP relies heavily on broadcast messages.
• Broadcast messages are generally limited to the subnet in
which they originate and are not forwarded to other
subnets.
• A DHCP relay agent is either a host or an IP router that
listens for DHCP (and BOOTP) client messages being
broadcast on a subnet and then forwards those DHCP
messages to a DHCP server on a remote subnet. The
DHCP server sends DHCP response messages back.
Dynamic Host Configuration Protocol
(DHCP)
Remote Access
• A Windows Server 2008 computer can act as a
remote access server, which can allow remote
network clients to access resources on a network
as though they were physically connected to the
LAN.
• The Windows Server 2008 remote access server
can provide remote access using either dial-up
connections via a modem or else through a
Virtual Private Network (VPN) connection over the
Internet or another public network.
Routing
• The process of transferring data across a network from
one LAN to another, provides the basis for TCP/IP
communications on the Internet and nearly all other
corporate networks.
• By configuring two network interface cards (NICs) within
a Windows Server 2008 server, the server can provide a
means of transmitting data from one network to another.
• For larger networks, the processing demands of network
routing are typically handled by dedicated hardwarebased routers.
Network Access Protection (NAP)
• One of the principal challenges in corporate networks is
the ability to secure networks against unwarranted
access.
• Network administrators also need to protect the network
against “inside threats,” laptop computers that are
physically brought inside the corporate network or that
gain access to the company network through remote
access technologies such as Virtual Private Networks
(VPNs.)
• Windows Server 2008 provides the Network Access
Protection platform, which provides a policy enforcement
mechanism to control access to a 2008 network.
Summary
• Network protocols create a logical language that
allows computers to communicate.
• The most commonly used network protocol on
modern networks is the Transmission Control
Protocol/Internet Protocol (TCP/IP) protocol suite.
• There are currently two implementations of
TCP/IP: TCP/IP version 4, or IPv4, and TCP/IP
version 6, or IPv6.
Summary
• Each host on a TCP/IP network needs to be
configured with a unique IP address.
• TCP/IP networks use the Domain Name System
(DNS) to map human-readable machine names to
IP addresses and vice versa, such as mapping the
www.cpandl.com host name to the 10.10.1.104 IP
address.
Summary
• Network administrators can use the Dynamic Host
Configuration Protocol (DHCP) to automatically
assign IP addresses to multiple client computers.
• The Routing and Remote Access service provides
the ability to use a Windows Server 2008
computer as a router, which passes network
traffic from one TCP/IP network to another, as
well as remote access capabilities using either
dial-up or VPN technology.
Summary
• To allow administrators to enforce network
security policies, such as mandatory anti-virus or
firewall configurations, Windows Server 2008 has
introduced the Network Access Protection (NAP)
enforcement platform.
• Network addressing is fundamental to successful
communication between systems.
Summary
• DNS provides name resolution to allow
meaningful names to be used to refer to network
addresses.
• DHCP is a simple, standard protocol that makes
TCP/IP network configuration much easier for the
administrator by dynamically assigning IP
addresses and providing additional configuration
information to DHCP clients automatically.
Summary
• Clients may be configured to use APIPA or an
alternate static IP address configuration if DHCP is
unavailable.