CCNA 1

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CCNA 1

• Module 9 TCP/IP Protocol Suite and IP Addressing

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TCP/IP History and Future

• Created by US DoD as a model able to withstand
  intense military attack and not fail.
• Data transmission was possible to any destination
  on the network under any circumstances.

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TCP/IP History and Future

• Standardized in 1981
• The TCP/IP model is now the standard on which the
  Internet is based.
• There are similarities and differences between
  the TCP/IP model and the nine layer OSI model.

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TCP/IP Application Layer

• Ensures that the data is properly packaged before
  being passed on.
• Handles high-level protocols, representation,
  encoding, and dialog control.
• Simple Network Management Protocol (SNMP)
  allows network managers to manage configurations,
  statistics, performance, and security.
• Domain Name System (DNS) used to translate
  domain names into IP addresses.

Application
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TCP/IP Application Layer

• Has protocols to support file transfer, e-mail,
  and remote login
• File Transfer
• Trivial File Transfer Protocol (TFTP)
  unreliable, connectionless User Datagram Protocol
  (UDP) service used to transfer configuration
  files, Cisco IOS images, and to transfer files in
  a LAN.
• File Transfer Protocol (FTP) reliable,
  connection-oriented service that uses TCP to
  transfer files between systems
• Network File System (NFS) allows file access to
  a remote storage device such as a hard disk

Application
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TCP/IP Application Layer

• E-mail
• Simple Mail Transfer Protocol (SMTP)
  administers the transmission of plain text e-mail
  over computer networks.
• Remote access
• Telnet remotely access a computer, enabling a
  user to log into an Internet host and execute
  commands. A Telnet client is called a local host.
  A Telnet server is called a remote host.

Application
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TCP/IP Transport Layer

• Provides a logical connection between a source
  host and a 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.

Transport
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TCP/IP Transport Layer
I just sent 10
I just received 10 Now I need 11
Transport
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
Transport
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
Transport
The sliding window has worked as the last packet
sent has arrived.
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TCP/IP Transport Layer

• The only Transport layer protocols are TCP and
  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)

Transport
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TCP/IP Internet Layer

• Two purposes are determining 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) - determines
  the MAC address, for a known IP address.
• Reverse Address Resolution Protocol (RARP) -
  determines the IP address for a known MAC
  address.

Internet
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TCP/IP Network Access Layer

• Allows an IP packet to make a physical link to
  the 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.

Network Access
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Comparing TCP/IP and OSI
TCP/IP Model
OSI Model
Application
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Application Layers
Application
6
Presentation
Session
5
Transport
4
Transport
3
Internet
Network
Data Flow Layers
2
Data Link
Network Access
Physical
1
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Comparing TCP/IP and OSI

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

• Differences
• TCP/IP combines the 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 as it has fewer layers.
• The 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.
• This means that it is independent of the lower
  layers and the upper layers.
• This functionality allows for different Layer 1
  and 2 LAN technologies (media protocols LAN
  design, etc.)
• It also allows for a diversity of applications at
  Layers 5, 6, and 7.

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Internet Architecture

• This means that one 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, is a
  combination of the network address and the host
  address creating a unique address for each device
  on a network. This 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 address is needed to deliver it to the
  destination device.

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IP Addressing

• An IP address is a 32-bit sequence 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

• A router uses the 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
  portion and a host portion.

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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 that can be represented is
  10000000, decimal 128.
• The highest number that can be 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 that can be represented 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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What is the Address Class?

• 1. 176.186.14.112 176 10110000
• 2. 197.76.210.100 197 11000101
• 3. 129.118.32.189 129 10000001
• 4. 113.26.172.106 113 01110001
• 5. 201.200.100.90 201 11001001
• 6. 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

• This is a very important table.
• Copy it into your journal.
• MEMORISE IT!

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Reserved 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 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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Public and Private Addresses
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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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IPv4 vs IPv6
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Obtaining an IP Address
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Obtaining an IP Address

• IP addresses can be 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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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 datagram on a LAN 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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Default Gateway

• The IP address of the router interface is stored
  in the network configuration of the host.
• The 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 the 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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• Do lab 9.2.7
• Do lab 9.3.7 at home

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Good luck on the exam..