chapter 1-3 the ethernet lan. ethernet the networking protocol used in most modern computer networks...

Chapter 1-3Chapter 1-3

The Ethernet LANThe Ethernet LAN

EthernetEthernet

The networking protocol used in The networking protocol used in most modern computer networks is most modern computer networks is Ethernet.Ethernet.

Ethernet is aEthernet is a CSMA/CD CSMA/CD LAN protocol. LAN protocol.

CSCS – Carrier Sense – Carrier Sense

MA MA – Multiple Access– Multiple Access

CDCD – Collision Detection – Collision Detection

Ethernet PacketEthernet Packet

The information in an Ethernet The information in an Ethernet network is exchanged in a packet network is exchanged in a packet form.form.

The packet provides grouping of the The packet provides grouping of the information for transmission.information for transmission.

The Ethernet PacketThe Ethernet Packet

Preamble – an alternating pattern of 1’s and 0’s used for synchronization


Start Frame Delimiter – a binary 8-bit sequence of 1 0 1 0 1 0 1 1 that indicates the start of the frame


Destination MAC Address and Source MAC Address – Each computer has an Ethernet network interface card (NIC) or network adapter that has a unique media access control (MAC) address associated with it.

The MAC address is 6 bytes (12 hex characters) in length.


Length / Type - an indication of the number of bytes in the data field if this value is less than 1500.

If this number is greater than 1500, it indicates the type of data format, for example IP or IPX.


This is the data being transferred from the source to the destination and destination to the source.


A field used to bring the total number of bytes up to the minimum of 46 if the data field is less than 46 bytes.


A 4-byte CRC (cyclic redundancy check) value used for error detection. The CRC is performed on the characters from the destination MAC address through the Pad fields. If an error is detected, the system retransmits the data.

A Network Interface CardA Network Interface Card

The MAC addressThe MAC address

How is the destination and source addresses How is the destination and source addresses for the data determined within a LAN? for the data determined within a LAN?

Networked devices, such as computers and Networked devices, such as computers and network printers each have an electronic network printers each have an electronic hardware interface to the LAN called a hardware interface to the LAN called a Network Interface Card (NIC)Network Interface Card (NIC) or or integrated network port. The NIC contains a integrated network port. The NIC contains a unique network address called the unique network address called the MAC MAC addressaddress. .

FIGURE 1-10 FIGURE 1-10 An example of a small office LAN star topology.An example of a small office LAN star topology.

Jeffrey S. BeasleyJeffrey S. BeasleyNetworking, 1eNetworking, 1e

Copyright ©2004 by Pearson Education, Copyright ©2004 by Pearson Education, Inc.Inc.

Upper Saddle River, New Jersey 07458Upper Saddle River, New Jersey 07458All rights reserved.All rights reserved.


The MAC address is 6 bytes (48 bits) in The MAC address is 6 bytes (48 bits) in length. length.

The address is displayed in 12 hexadecimal The address is displayed in 12 hexadecimal codes. The first 6 hexadecimal codes are codes. The first 6 hexadecimal codes are used to indicate the vendor of the network used to indicate the vendor of the network interface, also called the interface, also called the Organizationally Organizationally Unique Identifier (OUI)Unique Identifier (OUI)

the last 6 hexadecimal values are unique the last 6 hexadecimal values are unique numbers assigned by the vendor. numbers assigned by the vendor.

IEEE is the worldwide source of registered IEEE is the worldwide source of registered OUIs. OUIs.


Table 1-3 A Sample of MAC Addresses Table 1-3 A Sample of MAC Addresses

Company ID / Vendor Company ID / Vendor Manufacturer Manufacturer

Serial #Serial #

00-AA-00-B6-7A-5700-AA-00-B6-7A-57 Intel Corporation (00-AA-00)Intel Corporation (00-AA-00)

00-50-73-6C-32-1100-50-73-6C-32-11 Cisco Systems, Inc. (00-50-73)Cisco Systems, Inc. (00-50-73)

00-0A-27-B7-3E-F800-0A-27-B7-3E-F8 Apple Computer Inc. (00-0A-Apple Computer Inc. (00-0A-27)27)

the MAC addressthe MAC address

The MAC address, also called the The MAC address, also called the Ethernet, physical, hardware or Ethernet, physical, hardware or adapter addressadapter address

The MAC address can be obtained The MAC address can be obtained from computers operating under from computers operating under Microsoft Windows by typing the Microsoft Windows by typing the ipconfig /allipconfig /all command while in the command while in the command mode. command mode.

FIGURE 1-7 FIGURE 1-7 The Run window used to enter the command prompt in Windows XP.The Run window used to enter the command prompt in Windows XP.

Jeffrey S. BeasleyJeffrey S. BeasleyNetworking, 1eNetworking, 1e

Copyright ©2004 by Pearson Education, Copyright ©2004 by Pearson Education, Inc.Inc.

Upper Saddle River, New Jersey 07458Upper Saddle River, New Jersey 07458All rights reserved.All rights reserved.

The MAC address is listed under the Ethernet adapter Local Area Connection: heading. The Media State - Media disconnected text indicates that there is not an active Ethernet device connected to the computer. The Description lists the manufacturer and model of the network interface and the Physical Address of 00-10-A4-13-99-2E is the actual MAC address for the computer.

ipconfig /all demonstrationipconfig /all demonstration

• Click on Start – Run and enter the

command cmd

• Enter ipconfig /all to display the MAC address

IP AddressingIP Addressing

The MAC address provides the physical The MAC address provides the physical address for the network interface card, but address for the network interface card, but provides no information as to its network provides no information as to its network location or even on what LAN, or in which location or even on what LAN, or in which building, city, or even the country in which building, city, or even the country in which the network resides? the network resides?

IP addressing provides a solution to IP addressing provides a solution to worldwide addressing. worldwide addressing.

IPv4 AddressingIPv4 Addressing

The The IP addressIP address is a unique 32 bit address is a unique 32 bit address that identifies on which network the that identifies on which network the computer is located. The address is computer is located. The address is divided into four 8-bit parts. The format divided into four 8-bit parts. The format for the IP address isfor the IP address is

A . B . C. D.A . B . C. D.

where the A.B.C.D. values are written as where the A.B.C.D. values are written as the decimal equivalent of the 8-bit binary the decimal equivalent of the 8-bit binary value. The range for each of the decimal value. The range for each of the decimal values is 0 to 255. values is 0 to 255.

IPv4 AddressesIPv4 Addresses

IP addresses are issued based upon IP addresses are issued based upon the class of the network. Examples the class of the network. Examples of the classes of IP networks are of the classes of IP networks are provided in Table 1-4 of the text. provided in Table 1-4 of the text.

ClassClass DescriptionDescription Example IP Numbers Example IP Numbers

Class AClass A Governments, very large networksGovernments, very large networks 44.* .*.*44.* .*.*Class BClass B Midsize companies, universities, etc.Midsize companies, universities, etc. 128.123.".*128.123.".*Class CClass C Small networksSmall networks 192.168.1.*192.168.1.*

IPv4 AddressingIPv4 Addressing

Table 1-5Table 1-5 The Address Range for each Class The Address Range for each Class of of Network Network

Class A Class A 0.0.0.0 0.0.0.0 to 126.255.255.255to 126.255.255.255

Class BClass B 128.0.0.0 to 128.0.0.0 to 191.255.255.255191.255.255.255

Class CClass C 192.0.0.0 to 192.0.0.0 to 223.255.255.255223.255.255.255

IPv4 AddressingIPv4 Addressing network numbenetwork numberr is the portion of the IP address that is the portion of the IP address that

defines which network the IP packet is originating from or defines which network the IP packet is originating from or being delivered to. being delivered to.

The * entries for each class represent the The * entries for each class represent the host numberhost number. . The host number is the portion of the IP address that The host number is the portion of the IP address that defines the address of the networking device connected defines the address of the networking device connected to the network. The host number is also called the to the network. The host number is also called the host host addressaddress. .

10.10.20.20010.10.20.200172.16.25.191172.16.25.191

192.168.12.5192.168.12.5

IPv4 AddressingIPv4 Addressing The network number provides sufficient information for The network number provides sufficient information for

routing the data to the appropriate destination network. routing the data to the appropriate destination network.

The destination network then uses the remaining The destination network then uses the remaining information (the * portion) to direct the packet to the information (the * portion) to direct the packet to the destination computer or host. destination computer or host.

The * portion of the address is typically assigned by the The * portion of the address is typically assigned by the local network system administrator or is dynamically local network system administrator or is dynamically assigned when users need access outside their local assigned when users need access outside their local networks.networks.

10.10.20.20010.10.20.200 172.16.25.191172.16.25.191

192.168.12.5192.168.12.5

IPv4 Addressing - ISPIPv4 Addressing - ISP your your Internet Service Provider (ISP)Internet Service Provider (ISP)

dynamically assigns an IP address to your dynamically assigns an IP address to your computer when you log on to the Internet. computer when you log on to the Internet.

Remember, you can check the IP address Remember, you can check the IP address assigned to your computer by your ISP assigned to your computer by your ISP using the using the ipconfig ipconfig command in the command in the command prompt.command prompt.

10.10.20.20010.10.20.200 172.16.25.191172.16.25.191

192.168.12.5192.168.12.5

IPv4 Private AddressesIPv4 Private Addresses

Table 1-6 Private IP AddressesTable 1-6 Private IP Addresses

10.0.0.0 - 10.255.255.25510.0.0.0 - 10.255.255.255

172.16.0.0 - 172.31.255.255172.16.0.0 - 172.31.255.255

192.168.0.0 - 192.168.0.0 - 192.168.255.255192.168.255.255

Private IP AddressesPrivate IP Addresses

Private addresses are IP addresses set Private addresses are IP addresses set aside for use in private aside for use in private intranetsintranets. .

An intranet is an internal network that An intranet is an internal network that provides file and resource sharing. provides file and resource sharing.

Private addresses are not valid addresses Private addresses are not valid addresses for Internet use because they have been for Internet use because they have been reserved but can be used within a private reserved but can be used within a private LAN to create an LAN to create an IP networkIP network. .

IP NetworkIP Network An IP network is one that uses IP addressing for An IP network is one that uses IP addressing for

identifying devices connected to the network and is identifying devices connected to the network and is also the addressing scheme used in also the addressing scheme used in TCP/IPTCP/IP networks. networks.

TCP/IP stands for Transmission Control TCP/IP stands for Transmission Control Protocol/Internet Protocol and is the protocol suite Protocol/Internet Protocol and is the protocol suite used for internetworks such as the Internet. used for internetworks such as the Internet.

The topic of IP addressing will be examined in The topic of IP addressing will be examined in greater detail throughout the text. For Chapter 1 greater detail throughout the text. For Chapter 1 the objective is to use the IP addresses for the objective is to use the IP addresses for configuring the address of the computers for configuring the address of the computers for operation in a TCP/IP network. operation in a TCP/IP network.

Section 1-3 Key TermsSection 1-3 Key Terms

CSMA/CDCSMA/CD PacketPacket Network Interface CardNetwork Interface Card MAC AddressMAC Address Organizationally Unique Identifier Organizationally Unique Identifier

(OUI)(OUI) Ethernet, Physical, Hardware, or Ethernet, Physical, Hardware, or

Adapter AddressAdapter Address


ipconfig /allipconfig /all IANA – Internet Assigned Numbers IANA – Internet Assigned Numbers

Authority Authority IP addressIP address Network NumberNetwork Number Host NumberHost Number Host AddressHost Address


ISPISP Private AddressPrivate Address IntranetIntranet IP NetworkIP Network TCP/IPTCP/IP

chapter 1-3 the ethernet lan. ethernet the networking protocol used in most modern computer networks...

Documents

ethernet lan slide

ethernet packet preamble

network interface card

ethernet packet length

unique network address

source mac

frame slide

packet form