CCNA 1 Module 9

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CCNA 1 Module 9

• TCP/IP Protocol Suite and IP Addressing

"You don't get paid for the hour. You get paid
for the value you bring to the hour. "Don't wish
it were easier, wish you were better. - Jim
Rohn
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CCNA 1 Module 9 Objectives

• After completing this chapter you should be able
  to
• - Describe the TCP/IP model components
• - Describe the order of the four TCP/IP layers
  and how they relate to each other
• - Outline the responsibilities of each of the
  four TCP/IP layers, their components, services
  and functions
• - Compare and Contrast the TCP/IP and OSI models
• - Describe the format and significance of the
  each component of an IP network such as IP
  Addressing, Address Classes, private IP
  addressing, and IP subnetting
• - Calculate valid IP subnetwork addresses and
  mask values
• - Compare and Contrast IPv4 to IPv6
• - Describe how and why an administrator would
  want to use a static IP assignment
• - Describe how ARP, RARP and Proxy ARP work

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CCNA Pass

• Engineering Journal pages 83-92
• Concept Questions
• Focus Questions
• Exam Review Questions
• Lab Companion pages 165 178

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History and Future of TCP/IP

• DoD goal create a network to survive any attack
• TCP/IP model is the logical address standard
• IPv4 standardized in September 1981
• IPv4 addresses are 32 bits long, written in
  dotted decimal, and separated by periods
• IPv6 addresses are 128 bits long, written in
  hexadecimal, and separated by colons
• 1992 standardization of a new generation of IP,
  called IPng, supported by the Internet
  Engineering Task Force (IETF)
• IPng is now known as IPv6

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Application Layer

• Application layer handles high-level protocols,
  issues of representation, encoding, and dialog
  control
• Combines all application related issues into one
  layer
• Ensures data is properly packaged before being
  passed on
• TCP/IP protocols support file transfer, e-mail,
  and remote login, includes
• File Transfer Protocol (FTP)
• Trivial File Transfer Protocol (TFTP)
• Network File System (NFS)
• Simple Mail Transfer Protocol (SMTP)
• Terminal emulation (Telnet)
• Simple Network Management Protocol (SNMP)
• Domain Name System (DNS)

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TCP/IP Applications
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Transport Layer

• Provides a logical connection between source and
  destination host
• Transport Layer protocols segment and reassemble
  data sent by applications, into the same data
  stream, between end points
• Provides end-to-end control and reliability as
  data travels through the cloud, accomplished
  through
• sequence numbers, acknowledgments and sliding
  windows

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TCP/IP Transport Layer
I just sent 10
I just received 10 Now I need 11
This shows sequence numbers and acknowledgements.
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TCP/IP Transport Layer
Sliding Windows
I just sent 11, 12 and 13
I just received 12 Now I need 13
This indicates that packet 13 either did not
arrive, or arrived with errors, and needs
retransmission.
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TCP/IP Transport Layer
Sliding Windows
I just sent 13 and 14
I just received 14 Now I need 15
The sliding window has worked as the last packet
sent has arrived.
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TCP/IP Transport Layer

• Only Transport layer protocols are TCP UDP
• Transmission Control Protocol (TCP)
• Connection-oriented protocol
• End-to-end operation
• Flow control sliding windows
• Reliability sequence numbers and
  acknowledgments
• User Datagram Protocol (UDP)
• Connectionless
• Unreliable (no acknowledgments or error checking)
• Used when time is more critical than reliability

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Transport Layer Protocols
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TCP/IP Internet Layer

• Two purposes determine the best path and
  packet-switching
• No error checking or correction
• Protocols
• Internet Protocol (IP) - connectionless,
  best-effort delivery routing of packets
  determines best path to destination
• Internet Control Message Protocol (ICMP)
  control and messaging
• Address Resolution Protocol (ARP) Maps unknown
  MAC address to a known IP address
• Reverse Address Resolution Protocol (RARP) Maps
  unknown IP address to a known MAC address

Internet
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Internet Layer Protocols
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Network Access Layer

• The network access layer is also called the
  host-to-network layer.
• The network access layer is the layer that is
  concerned with all of the issues that an IP
  packet requires to actually make a physical link
  to the network media.
• It includes the LAN and WAN technology details,
  and all the details contained in the OSI physical
  and data-link layers.
• The network access layer defines the procedures
  for interfacing with the network hardware and
  accessing the transmission medium.
• Because of an intricate interplay of hardware,
  software, and transmission-medium specifications,
  there are many protocols operating at this layer.
  
• Network access layer functions include mapping IP
  addresses to physical hardware addresses and
  encapsulation of IP packets into frames.
• Based upon the hardware type and the network
  interface, the network access layer will define
  the connection with the physical network media.

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Network Access Protocols
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TCP/IP Network Access Layer

• Enables IP packet to make a physical link to
  network media
• Maps IP addresses to MAC addresses
• Encapsulates IP packets into frames
• Drivers for software applications, modem cards,
  and other devices operate at the network access
  layer
• Serial Line Internet Protocol (SLIP) and
  Point-to-Point Protocol (PPP) provide network
  access
• ARP and RARP also work at this layer

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Comparing TCP/IP and OSI
OSI Model
TCP/IP Model
Application
Application
Application Layers
Presentation
Session
Transport
Transport
Data Flow Layers
Network
Internet
Data Link
Network Access
Physical
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Comparing TCP/IP and OSI

• Similarities
• Both have layers
• Both have application layers, though include
  different services
• Both have comparable transport and network layers
  
• Both use packet-switched instead of
  circuit-switched technology

• Differences
• TCP/IP combines OSI application, presentation,
  and session layers into its application layer
• TCP/IP combines the OSI data link and physical
  layers into its network access layer
• TCP/IP appears simpler with fewer layers
• TCP/IP transport layer uses UDP (not reliable)
  delivery of packets. The transport layer in the
  OSI model is always reliable

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Internet Architecture

• The Internet is based on the principle of network
  layer interconnection
• Independent of both lower and upper layers
• This functionality allows for different Layer 1
  and 2 LAN technologies (media protocols LAN
  design, etc.)
• Allows for a diversity of applications at Layers
  5, 6, and 7

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Internet Architecture

• Therefore a network with one set of Layer 1 and 2
  LAN media, design etc. and its own upper layer
  Applications can communicate with a very
  different LAN
• This capability means that the Internet is
  scalable now with over 90,000 core routers and
  300 million users, and growing!!!

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IP Addressing
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IP Addressing

• Each computer (computer interface) in a TCP/IP
  network must have two addresses
• An IP (logical, layer 3) address, a combination
  of the network address and the host address
  creating a unique address for each device on a
  network. This logical address is needed to
  deliver the packet to the correct network
• A unique MAC (physical, layer 2) address. Once
  the data (packet) has arrived at the network,
  this local address is needed to deliver it to the
  destination device

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IP Addressing

• An IP address is a 32-bit binary stream of ones
  and zeros
• It is commonly represented in dotted decimal
  format, as it is easier to understand and less
  prone to error

11000000.10101000.00000001.00001000 192.168.1.8
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Decimal and Binary Conversion

• Review the binary to decimal and the decimal to
  binary conversions in 9.2.2

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Address Classes

• Routers use an IP address of the destination
  network to deliver a packet to the correct
  network.
• Every IP address has two parts
• The first part identifies the network where the
  device is connected and the second part
  identifies the device
• There are four octets, each ranging from 0-255,
  representing 256 possible addresses

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Address Classes

• An IP address is always divided up into a network
  field and a host field

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Address Classes

• IP addresses are hierarchical, meaning an address
  can be referenced back to a particular group
  address

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Address Classes

• There are five address classes
• Class A for very large networks
• Class B for medium networks
• Class C for small networks
• Class D for multicast groups no need for
  network and host parts
• Class E for research purposes

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Address Classes
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Address Classes
Learn these tables!
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Address Classes
Class A

• One network octet and three host octets
• The first bit of a Class A address is 0
• The lowest number that can be represented is
  00000000, decimal 0
• The highest number that can be represented is
  01111111, decimal 127
• Usable 1st octet addresses 1 126
• (0 and 127 are reserved addresses)

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Address Classes
Class B

• Two network octets and two host octets.
• The first two bits of a Class B address are 10.
• The lowest number represented is 10000000,
  decimal 128
• The highest number represented is 10111111,
  decimal 191
• Usable 1st octet addresses 128 191

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Address Classes
Class C

• Three network octets and one host octet.
• The first three bits of a Class C address are 110
• The lowest number that can be represented is
  11000000, decimal 192
• The highest number possible is 11011111, decimal
  223
• Usable 1st octet addresses 192 223

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Address Classes
Class D

• Created to enable multicasting. A destination
  address is a group of addresses
• The first four bits of a Class D address must be
  1110
• The first octet range for Class D addresses is
  11100000 to 11101111, or 224 to 239

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Address Classes
Class E

• Reserved for IETF research
• Not used on the Internet
• The first four bits of a Class E address are
  always 1111
• The first octet range for Class E addresses is
  11110000 to 11111111, or 240 to 255

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Address Class Prefixes and Address Ranges
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What is the Address Class?

• 176.186.14.112 176 10110000
• 197.76.210.100 197 11000101
• 129.118.32.189 129 10000001
• 113.26.172.106 113 01110001
• 201.200.100.90 201 11001001
• 47.145.148.211 47 00101111

B
C
B
A
C
A
What do you notice about each of the Class
addresses? What is common with the Class A
addresses? What is common with the Class B
addresses? What is common with the Class C
addresses?
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Address Classes

• Critical table
• Copy it into your journal
• Commit to memory!!!

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Reserved IP Addresses

• Two addresses on any network cannot be used by
  hosts
• Network address Used to identify the network
  itself
• Broadcast address Used for broadcasting packets
  to all the devices on a network
• The HOST bits of a network address are all 0s
• The HOST bits of a broadcast address are all 1s

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Reserved addresses
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Reserved addresses

• IP Address 10.18.127.100
• Subnet Mask
• Network address
• Broadcast address

255.0.0.0
10.0.0.0
10.255.255.255
The first question to ask is, What class is this
address?
Class A
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Reserved addresses

• IP Address 131.234.12.66
• Subnet Mask
• Network address
• Broadcast address

255.255.0.0
131.234.0.0
131.234.255.255
What class is this address?
Class B
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Reserved addresses

• IP Address 199.218.4.56
• Subnet Mask
• Network address
• Broadcast address

255.255.255.0
199.218.4.0
199.218.4.255
What class is this address?
Class C
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Reserved addresses

• IP Address 210.189.137.100
• Subnet Mask 255.255.255.240
• Network address
• Broadcast address

210.189.137.96
210.189.137.111
What class is this address?
Class C
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Reserved addresses

• IP Address 180.43.120.39
• Subnet Mask 255.255.255.192
• Network address
• Broadcast address

180.43.120.0
180.43.120.63
What class is this address?
Class B
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Public and Private IP Addresses

• No two devices on the Internet can have the same
  IP address
• Ensuring this does not happen is handled by the
  Internet Assigned Numbers Authority (IANA)
• With the growth of the Internet, available
  Internet addresses have nearly run out
• To help deal with this problem, RFC 1918 sets
  aside three blocks of IP addresses for private,
  internal use

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Public and Private Addresses

• One Class A, a range of Class B addresses, and a
  range of Class C addresses are not routed on the
  Internet.
• 10.0.0.0 10.255.255.255
• 172.16.0.0 172.31.255.255
• 192.168.0.0 192.168.255.255
• A router uses Network Address Translation (NAT)
  to translate private addresses to public
  addresses

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• Subnets
• Breaking up
• Classful
• Networks

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Subnets

• Subnetting a network means to use the subnet mask
  to divide a up a network into smaller, segments,
  or subnets.
• Subnetting has prevented the wasting of usable
  host addresses.
• To create a subnet address, some bits from the
  host field are borrowed, and designated as subnet
  bits.

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Subnets

• The minimum number of bits that can be borrowed
  is two.
• The maximum is two less than the available number
  of host bits.

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IPv4 vs IPv6

• Class A and Class B addresses make up three
  quarters of the four billion possible addresses.
  These are virtually used up.
• Class C addresses only allow 254 hosts, too small
  for many organisations.
• In 1992 the Internet Engineering Task Force
  (IETF) began work on IP version 6.

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IPv4 vs IPv6
IPv4 addresses are 32 bits long. IPv6 addresses
are 128 bits long. IPv6 addresses are assigned to
interfaces, not nodes. IPv6 addresses are
written in hexadecimal, and separated by colons
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Obtaining an IP Address

• IP addresses are assigned statically or
  dynamically
• Static addressing is manually done by a system
  administrator
• Best on small, infrequently changing networks
• Good record-keeping is essential
• Servers, printers and routers should be given
  static addresses
• Static addressing is NOT scalable

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RARP IP Addressing

• Reverse Address Resolution Protocol (RARP)
  associates a known MAC addresses with an IP
  addresses
• IP source addresses are needed for the address
  field in all IP packets
• RARP used in diskless workstations
• A RARP server must be present
• RARP requests are broadcast onto the LAN and are
  responded to by the RARP server, usually a router

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BOOTP IP Addressing

• Operates in a client-server environment
• BOOTP was not designed for dynamic address
  assignment
• The administrator must maintain the BOOTP
  database with profiles for each host
• BOOTP is used when a device starts up
• BOOTP uses UDP to carry messages
• BOOTP sends a broadcast IP packet
• A BOOTP server receives the broadcast and then
  sends back a broadcast

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BOOTP Data Storage
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DHCP IP Addressing

• DHCP has replaced BOOTP.
• DHCP allows a host to obtain an IP address
  dynamically without needing an individual profile
  for each device.
• All that is needed is a defined range of IP
  addresses on a DHCP server.
• Information sent includes the subnet mask and the
  leased address.
• Users can be mobile and keep the same address.
• DHCP offers a one to many ratio of IP addresses,
  and that an address is available to anyone who
  connects to the network.

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Address resolution

• A LAN datagram must contain both a destination
  MAC address and a destination IP address
• These addresses must be correct and match the
  destination MAC and IP addresses of the host
  device.
• If it does not match, the datagram will be
  discarded by the destination host.

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ARP Address Resolution Protocol

• ARP tables store MAC and IP addresses of other
  LAN devices.
• Maintained automatically
• Stored in RAM

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ARP Address Resolution Protocol

• Two ways to gather MAC addresses
• Monitor traffic and record the addresses
• Broadcast an ARP request
• An ARP request is used if a device needs an IP
  and MAC address pair.
• The broadcast is sent
• If the device exists and is on line, it will
  reply.
• If the device does not exist or is turned off,
  there is no response to the ARP request. In this
  situation, the source device reports an error.

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Proxy ARP

• A router sends an ARP response with the MAC
  address of the interface on which the request was
  received, to the requesting host.
• This is done for addresses not in local subnet.

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ARP Table Entry
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Default Gateway

• The IP address of the closest router interface is
  stored in the network configuration of the host
• Source host compares the destination IP address
  and its own IP address to determine if the two IP
  addresses are located on the same segment
• If receiving host is not on the same segment, the
  source host sends the data using the actual IP
  address of the destination and the MAC address of
  the router
• Either Proxy ARP or the Default Gateway must be
  configured, or no traffic can leave the LAN

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Summary

• At this time you should be able to
• - Describe the TCP/IP model components
• - Describe the order of the four TCP/IP layers
  and how they relate to each other
• - Outline the responsibilities of each of the
  four TCP/IP layers, their components, services
  and functions
• - Compare and Contrast the TCP/IP and OSI models
• - Describe the format and significance of the
  each component of an IP network such as IP
  Addressing, Address Classes, private IP
  addressing, and IP subnetting
• - Calculate valid IP subnetwork addresses and
  mask values
• - Compare and Contrast IPv4 to IPv6
• - Describe how and why an administrator would
  want to use a static IP assignment
• - Describe how ARP, RARP and Proxy ARP work

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Questions