Upload
oscar-perry
View
224
Download
0
Embed Size (px)
Citation preview
14-1© 2001 by Prentice Hall
Local Area Networks, 3rd EditionDavid A. Stamper
Part 5: Connecting to Other Systems
and Networks
Chapter 15
Internet Technology
14-2© 2001 by Prentice Hall
Chapter Preview
• Describe the TCP/IP protocol• Discuss Internet addressing• Describe several protocols used on
the Internet• Define a subnet and describe how
they are used• List several components of the TCP/IP
protocol suite
In this chapter you will study:
14-3© 2001 by Prentice Hall
Internet Addresses
• Internet addresses are represented in a variety of formats; however, all the formats are ultimately resolved to a 32-bit number known as an IP address.
• A 128-bit address is part of a new version of the IP protocol.
• On the Internet, all network addresses must be unique. Within a network, all subnet addresses must be unique, and within a subnet all node addresses must be unique.
• Currently there are four address classes, A through D; Class E is defined but reserved for future use.
14-4© 2001 by Prentice Hall
Internet Address Class Summary
A
B
C
D
27 = 128
214 = 16,000
221 = 2 million
224 = 16 million
216 = 64,000
28 = 256
Address begins with a 0 bit
Address begins with bits 10
Address begins with bits 110
Address begins with bits 1110
Class Subnets Nodes Comments
14-5© 2001 by Prentice Hall
Subnet Addresses
• An Internet address is composed of three basic parts: the class type identifier, the network address, and the node addresses. An installation that was fortunate to have a Class A address space has the potential for approximately 16 million node addresses. It is unlikely that the company would want all these nodes associated with a single network address. Consequently, it is possible for a company to divide the node address range into two parts, a subnet address and a node address within the subnet.
• This is accomplished by placing a subnet mask over the local or node address part of the IP address.
14-6© 2001 by Prentice Hall
Internet Node Addresses
• Static Addressing– Static addressing means that a node is assigned a permanent IP address. This
is common for nodes that are continuously operating on the Internet or network using TCP/IP.
• Dynamic Addressing– In dynamic addressing, a node is assigned an Internet address when one is
needed. With dynamic addressing, a node will be given any address that is not currently in use. The most common mechanism for dynamically assigning Internet addresses is the dynamic host configuration protocol (DHCP).
• Internet Addressing on LANs– If a LAN node also has an IP address, an IP message can be delivered only if
the IP address is first translated into MAC address. The protocol that performs this function is called the address resolution protocol (ARP).
14-7© 2001 by Prentice Hall
IP Routing
• Devices called routers are responsible for internetwork message forwarding. Each router is connected to two (or more) networks (some routers have more than two ports), and each router port has an address on the attached subnet.
• Each router maintains a router table.• Internet Naming Conventions
– For most Internet users, the four-octet address representation, called a dotted decimal, is too cumbersome. Therefore, most users substitute a naming convention called a uniform resource locator (URL). A URL uses names and abbreviations that are easier to use and remember than the dotted decimal representation.
– Domain names are a hierarchical word-oriented representation of an Internet address.
14-8© 2001 by Prentice Hall
Root Level Domain Names
Commercial enterpriseeducation, for example, a universityU.S. governmentU.S. militarynetwork servicenonprofit organizationAustriaAustraliaBelgiumCanadaDenmarkSpainFinlandFranceItaly JapanUnited States
Comedugovmilnetorgataubecadeesfifritjpus
14-9© 2001 by Prentice Hall
Domain Name Hierarchy
AF AU CA CN DE FR JP...US...ZW
COM EDU GOV MIL NET ORG
CountriesMost General
Organizational
ABC Acme BGH….XYZ
grumpy doc sneezy… bashful
Companies
Hosts
14-10© 2001 by Prentice Hall
Some URL Protocols
hypertext transfer protocol
file transfer protocol
file access
Send mail to a recipient.
Access a newsgroup or new article.
Use the Gopher text-oriented access.
Use utility to access information about a user.
http
ftp
file
mailto
news
Gopher
finger
14-11© 2001 by Prentice Hall
IP Routing Algorithm
• Source node obtains the destination node’s IP address.• IP protocol builds the IP header and affixes it to the packet• Send packet to router.• Determine the network address of the destination node.• If the network address is this network, use local delivery
method and skip remaining steps.• Router consults routing table for network address.• Router sends message out on port addressed to next router• Receiving router decrements time-to-live field.• If time-to-live field is 0, packet is discarded.• Return to step 3.
14-12© 2001 by Prentice Hall
Internet Tools
• Finger– Finger is a utility that allows a user to gather information about other network users. For
security reasons, some systems do not allow the use of this utility.
• Tracert– Tracert allows a user to trace the round trip between the user’s node and another node
on the network.
• Ping– Ping allows a user to determine if a given system is active on the network. Some
versions of Ping also give performance information like number of hops to the system and speed of the links if the system is available.
• Talk and Internet Relay Chat (IRC)– Talk is a UNIX utility that allows on user to communicate interactively with another user.
Through the talk utility, characters typed at one station are immediately displayed on the other participant’s monitor.
14-13© 2001 by Prentice Hall
Key Upgrades in IPv6
• Expanded Address Space– Currently, the length of Internet addresses is 32 bits. This gives an address space of
approximately 4 billion; however, the actual number of addresses available is less than that because some addresses are reserved and because some address ina class may not be used. IPv6 increases the size of the address field to 128 bits; this will allow an address space from 0 to 3x1038.
• Quality of Service– To accommodate time-sensitive transmissions like audio and video, IPv6 will institute service
categories to prioritize the flow of data. Transmissions declared as real-time will be provided with improved performance.
• IP Header Changes– Changes will be necessary to provide for the larger address space and quality of service.
• Security and Privacy– IPv6 will allow extensions to the header to provide security capabilities. The extensions will
allow a variety of authentication algorithms and allow detection or elimination of known techniques for one node to impersonate another node for sending or receiving packets.
14-14© 2001 by Prentice Hall
Ipv6 Header Format
Version
Priority
Flow control
Payload length
Next header
Hop limit
Source address
Destination address
Contains protocol version 6 for Ipv6
Message priority
Quality-of-service identifier
Size in octets of packet following the header
Type of header extension, if any
Number of hops allowed before datagram is discarded
Sender’s IP address
Recipient’s IP address
4
4
24
16
8
8
128
128
Field Size in Bits Comments
14-15© 2001 by Prentice Hall
A Generic Firewall
Protected Systems
The Internet
GenericFirewall
LAN
14-16© 2001 by Prentice Hall
A Gateway Firewall
The Internet Private Network
GatewayFirewall
14-17© 2001 by Prentice Hall
A Screened Subnet Firewall
The Internet Private Network
Screened Subnet(Private)
Traffic AllowedTraffic Allowed
Traffic Not Allowed
14-18© 2001 by Prentice Hall
Information Superhighway Uses
• A business might use the information superhighway to conduct a conference among employees in different locations.
• A software company might use the information superhighway to distribute software directly to customers.
• A publishing company might distribute books or magazines directly to readers or perhaps to a local outlet for on-demand printing.
• Movies and games may be available on demand.• Education classes at all levels may be available and allow
people to learn new skills at their home or office.• Electronic mail and video images may be exchanged.
Interactive use of such technologies may give rise to online discussion groups and conferencing.
14-19© 2001 by Prentice Hall
Potential Information Superhighway Implementation
Large Business
Local DistributionPoint
Homes orSmall Businesses
Coaxial Cableor Twisted-Pair Wires
Fiber OpticCable
BackboneNetwork
Fiber OpticCable