1. Chapter 4 Network Addressing
Copyright © Wiley
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
expanded by Jozef Goetz, 2014

2. OBJECTIVES About physical addressing. About logical addressing.
About IPv4 and its limitations.
How to convert binary (or other number systems) to decimal and decimal to binary (or other number systems) .
What subnetting is and how it works.
How to determine subnets.
About IPv6 and its advantages.
How physical and logical addressing work together to move packets around a network.
What NAT (Network Address Translation) is and how it works.
About public versus private addressing.
How SNAT and PAT are necessary for NAT to work.
About static IP addressing.
About dynamic addressing.
How DHCP works.
What unicast, broadcast, and multicast are and when they are used.

3. Physical Addressing
Physical address is the physical binary address every network device is given by its manufacturer; hard coded
Also known as the device’s MAC - Media Access Control address
Physical address of a network device is 48 bits long
Made up of 1s and 0s
Physical address generally expressed in hexadecimal format

4. Physical Addressing Hexadecimal Binary: 91-FC-5D-D9-A3-B0
First 24 bits is Organizationally Unique Identifier – represents the company
Last 24 bits is host portion - each manufacturer gives unique portions of their physical address – can generate up to 16,777,216 devices

5. EUI-60 and EUI-64 Variations on conventional MAC address
60-bit Extended Unique Identifier (EUI-60)
The host extension is 36-bits long rather than 24-bits long
64-bit Extended Unique Identifier (EUI-64)
The host extension is 40 bits long, allowing for more host addresses per OUI
91-FC-5D-D9-A3-B0-|AD-CD
IPv6 can use EUI-64 to create a unique interface identifier

6. MAC Addressing
Refers to the function of the physical address, while the term “physical address” more often refers to the actual thing
MAC address = physical address
Function: A computer or network device uses the MAC address to move data frames from one computer or network device to an adjacent computer or network device
Hop: Each time a computer or network device hands off data frame to the next computer or network device down the line

7. Spoofing MAC Addresses p.84
To trick other computers on a network into thinking a computer's MAC address is one physical address when it is actually a different physical address
Hackers use MAC spoofing to gain access to a network

8. Logical Addressing
Every computer on a network needs a unique logical address
Used to ensure data packet follows best path to destination computer

9. Internet Protocol Version 4 (IPv4)
IPv4 logical address is 32 bits long
4 groups of 8 bits called octets
Expressed in 8-bit decimal format
expressed in 8-bit decimal format as
4 billion addresses in IPv4 address space, but have all been used

10. Subnetting
Breaking up an IP address range into smaller pieces so a given range of IP addresses can be used in more than one network
IP address has a network portion and a host portion
Network: First three octets
Host: Last octet

11. Subnet Masks Subnet mask is a series of 1s and 0s
Computer uses subnet mask to determine which part of the IP address is the network ID versus which part is the host
Subnet mask is all 1s (network) followed by all 0s (host)
For subnet mask , binary equivalent is

12. Logical AND Truth Table
ANDing
Computer uses a logical AND truth table to compare the full IP address of the computer to the subnet mask

13. ANDing Example
Computer uses a logical AND truth table to compare the full IP address of the computer to the subnet mask
<=mask
Result of ANDing with the subnet mask

14. Classful IP Addressing
Class A, B, C, D, and E
A, B, and C used by general population
Classful IP addressing
The classful method of determining what portion of an IP address is network ID and what portion of an IP address denotes hosts

15. where # is written in decimal from 0 -255
IP Addresses
IP address formats.
The addresses used in with the IP protocol are our standard IP addresses of the form #.#.#.#
where # is written in decimal from
• The IP address is not actually the address of the machine, but the address of the network interface.
• If a computer had two connections to two networks, it would also have two IP addresses.

16. IP Address Classes and Some Defining Characteristics

17. The Three Bears Problem
We can only have 128 Class A networks (/8) with 16 million hosts each – too big.
We can have 16,384 Class B networks (/16) with 65 k hosts each –too large for most organization
this scheme forces medium sized nets to choose class B addresses, which wasted space
b/c more than 50% of all class B network have < 50 hosts
We can have 2 million Class C networks (/24) with 256 hosts each – much too small
10 bits would give 1022 hosts; it would give ½ million networks vs 16 k class B network
Pr: each router in the world should have ½ million entries per network
There are too many people under-utilizing Class B networks, resulting in a shortage in IP addresses. ADSL users add to the world problem of running out of IP addresses.

18. Special IP Addresses
loopback: send to the local network without knowing its #

19. IP Ranges Set Aside for Various Uses

20. Classless IP Addressing
Host and network portions of an IP address is calculated based on the subnet mask
The class of an IP address not considered
Example: IP address
If subnet mask = , then 192 is network and the rest host
If subnet mask = , then network portion is and host portion is

21. Classless Inter-Domain Routing (CIDR)
Standard (shorthand) notation that indicates network ID and host ID of an IP address
Format is similar to /n
/n indicates how many of the total 32 bits of the IP address’ binary form are to be used for the network IP portion
i.e., tells what the subnet mask is
/n can be any number between 1 and 32, but 2 through 30 are used in practice

22. CIDR Examples 192.130.227.27/8 indicates the subnet mask is 255.0.0.0

23. Binary Conversion—Base 10 Example
The number 14,609,182 placed into a base 10 number system table
14,609,182 can be expressed as:
Please refer to my L_04_Ex_of_number_conversion.ppt

24. Binary Conversion—Base 2 Example
Binary value in base 2 number system out to 8 bits
Add decimal values that have a 1 under them: = 227

25. Converting Decimal to Binary
Convert 130 to binary
Which number in second row of table is the largest number that we can subtract from 130 without exceeding 130? Answer: 128
Place a 1 in row 3 under “128” in the table

26. Converting Decimal to Binary Example
130 – 128 = 2
The largest number in the table that can be successfully subtracted from 2 is 2, so place a 1 in row 3 under the “2”

27. Converting Decimal to Binary Example
2 - 2 = 0
There is no 0 place in the table, so we are finished
Put a 0 in all row 3 positions that do not contain 1s
Binary equivalent of 130 is

28. Determine Subnet Mask Using CIDR
Ex: CIDR notation is /12
Use the value 8 to determine the subnet mask in each octet
12 – 8 = 4
First octet has eight 1s, second octet uses the remaining four 1s
An octet with eight 1s is 255, so first octet of the subnet mask is 255

29. Determine Subnet Mask Using CIDR
With 4 in the /n portion of the CIDR notation, the first four places in the second octet of the subnet mask starting with the leftmost place are all 1s
Binary =
Enter into table, value converts to 240

30. Determine Subnet Mask Using CIDR
The value 240 should be in the second octet of the subnet mask
Since 4 is smaller than 8, there are no 1s in the last two octets and so they will equal 0
The subnet mask that results from the CIDR notation /12 is therefore

31. Determine Sub-network Ranges Using CIDR
CIDR notation can determine sub-network ranges
Sub-network is where a specific network IP address is divided into smaller networks to make more efficient use of the available IP addresses.

32. Values in Subnetting Class C Subnets
4rd col. X 3rd col = 256
based on 1st col.
Last octet of Class C
Always 2nd + 3rd column = 256
Last col. : 2 hosts are
not available for 3rd to 7th rows
5th : 2 networks are
not available for some rows

33. Value Changes by Increments of 64 in the Last Octet of 207. 253. 187
Problem: The company bought from ICANNA class C IP address /26 and
need 3 (sub)networks with a min of 25 IP addresses in each one (but has only one IP).
The network ID = and the mask is for class C. So, the solution is to break up the network range through into smaller networks.
Step 1: 26 / 8 = 3 octets reminder 2 bits left ( i.e. 4 combinations for sub-networks) over 3 octets. So 2 bits should have 1s in lowest octet. Then Value Changes by Increments of 64 = So the last part of the mask is = 192 (see the previous table => subnet network increment for the subnet mask = 192). The corresponding subnet mask is

34. Absolute Network Ranges Using CIDR 207.253.187.0/26
Step 2: Usable Network Ranges from all usable networks, using CIDR /26
R1: the 1st and last IP addresses in any given range of networks cannot be used for a host value and
R2: the 1st one and the last one is not usable for Network 2 and 3 (for the network/segment ID and for broadcasting purpose)

35. Values in Subnetting Class C Subnets
Step 3: We need 3 usable networks: the 4th row gives us => so we need to go every 32 increments,

36. The 207.253.187.0/27 Network Solution for the company:
By subnetting the /27 (not /26) network the company has 6 usable networks with each network containing 30 usable IP addresses . This meets the company requirements.
So the last part of the mask is = 224. The corresponding subnet mask is and unusable ID for the last octet starts from We can see the last octet will correspond exactly to the host ID. .

37. Internet Protocol Version 6 (IPv6)
L_04-p.II
Uses 128-bit IP addresses (instead of 32 bit => 4 billions IP addresses)
addresses expressed in hexadecimal numbers
32 hex digits
first 16 hexadecimal digits are network ID, last 16 hexadecimal digits are host ID.
Each one is broken into 4 sets of hex digits separated by the colon.
Example:
13D4:FA97:0000:1258:AD8B:1009:34D6:1800
No subnetting needed

38. Binary to Hexadecimal Conversion
Replace every four 1s and 0s with the equivalent hexadecimal value

39. IPv6 Address Double Colon Technique
Not all eight 16-bit groups in IPv6 address need to be shown
If IPv6 address has a group of 16 bits equal to all 0s, that 16-bit section can be skipped
13D4:0000:0000:0000:0000:1009:34D6:1800
can be written as
13D4::1009:34D6:1800

40. Extended Unique ID =>EUI-64
Host can automatically assign itself a unique 64-bit interface identifier
Two steps:
Divide MAC address (48 bit) 91-FC-5D-D9-A3-B0
between the Organizationally Unique Identifier (OUI) and the host portion of the MAC address
Add hexadecimal value FFFE between two portions of the MAC address:
91-FC-5D- FFFE-D9-A3-B0
So a 64-bit MAC is called a EUI-64
Defined in IEEE Guidelines for EIU-64 Registration Authority and RFC 2373

41. EUI-64 (Continued)
Invert 7th bit of MAC address so it is opposite of what it was previously
This bit is called the universal/local flag
Normally set to 0; to invert, change to 1
91-FC-5D- FFFE-D9-A3-B0 converted to
91-FC-5D- FFFE-D9-A3-F0
Result is a Modified EUI-64 address
Can be used by IPv6 as a unique interface identifier on a device connected to a network
Defined in IEEE Guidelines for EIU-64 Registration Authority and RFC 2373

42. How Physical and Logical Addressing Work Together
This portion of lesson shows how logical addresses and physical addresses work together to ensure that data finds destination across a large network
For illustration purposes, assume represented network uses Ethernet for both its LAN and WAN portions

43. Simplified Form of an internetwork
Switches =>
Routers =>
WAN connection
WAN connection
Switches =>
Network diagram symbols:
• Circular symbols with two arrows pointing outward and two arrows pointing inward represent standard routers.
• Rectangular symbols with two arrows pointing in one direction and two arrows pointing in the opposite direction represent standard switches.
• Small computers represent network workstations.
• Lightning bolts represent the WAN connection between each router.
• Solid lines between each computer and switch as well as each switch and router represent standard Ethernet connections.
Solid lines between each computer and switch as well as each switch and
router represent standard Ethernet connections.

44. Internetwork with Letters Representing MAC Addresses
Routers =>
have 4 cards/interfaces
Switches don’t have a unique MAC address.
For the purpose of illustration, just assume
that the each port takes on the MAC address of the computer that is attached to it.

45. Internetwork Segments
Large network needs to be broken down into smaller components
Avoids overwhelming network capacity
Each component is called a segment
Also called
collision domains or
broadcast domains

46. Different Segments or Collision Domains of the Internetwork
The network interfaces within a given segment must have unique MAC addresses

47. Segments Need Unique Logical Addresses
Each network segment requires a unique network or logical address, represented by an IP address
WAN connection
considered as a segment

48. unique host #s within the segment
Internetwork Segments with Unique Logical Addresses Assigned to Each Device
Each network interface (on a router) within each segment also requires a unique network or logical address
Network address for each device within a segment must contain the network address of the entire segment as well as a unique identifier for each interface
Each network segment is given a logical address that ends in a 0 in the last section of the address. In this diagram, that is the logical address for that entire segment. The portion of the logical address that is not the number 0 in our diagram is called the network address.
unique host #s within the segment

49. Source Computer and Its Intended Destination in Internetwork
Source computer on one end of the internetwork and its intended destination on the other
IPs are used across segments and are kept in the frames

50. Resetting Source and Destination Physical Addresses at Each Hop
Source computer knows the physical address of the router that is part of its segment.
Logical addresses are unchanged, but the destination physical address is changed to that of the route
The source computer doesn’t know the MAC address of the destination computer but knows the router’s MAC

51. Second Hop A to J
Logical addresses stay the same but the source physical address changes to A and destination physical addresses changes to J
The router receives the data frame from the previous one and analyzes the logical address of the data frame.
The router determines that the destination is not in the segment directly connected to it, so it again changes the source and destination physical addresses and passes on the next router.

52. Third Hop L to T
No destination IP is available within segments directly connected to the 2nd router. So go futher.
Logical source and destination addresses are not changed when the frame moves
Logical addresses stay the same but the source physical address changes to J and destination physical addresses changes to T

53. Final Hop
Logical addresses again stay the same, but the source physical address is changed to T and the destination physical address is changed to Z

54. Broadcast Domain
All devices on a network or a segment are connected together so they all receive the same broadcast signal from a computer – it is called Broadcast Domain
Signal received cannot pass through a switch, router, or similar device

55. Collision Domain
Two or more devices on the same segment or network are able to cause their signal to interfere with the signal from another device on the same segment or network
A hub => many devices connected form a collision and a broadcast domain
A switch used in place of the hub=> many devices connected cannot form a collision
b/c any one device connected to the switch is only able to communicate directly to only one other device
but a broadcast domain is form.

56. Other Addressing Technologies to overcome limitations of IPv4
Supernetting
Network Address Translation (NAT)
Assigning IP addresses
Addressing schemes

57. 1. Supernetting
The process of combining several IP ranges, usually Class C ranges, into one larger network
Example
Two IP address ranges: and
Combine (supernet) them into one aggregate range of IP addresses
Use the CIDR notation of /23 => 9 bits for hosts for each network,
which result in a network range that support 512 hosts – 1st and last host IDs, which used for network ID and broadcast ID

58. 2. Network Address Translation (NAT)
Take an IP address from an ISP or other location and use that one IP address to allow all Internet-enable devices to which it is connected to access the Internet

59. Types of NAT
Source Network Address Translation (SNAT) - when the network changes the source IP address to trick the modem – see an example later
Port Address Translation (PAT) is what NAT uses to keep track of which device asked for info in order to route back correctly.
A table found in the device keeps private and public addresses.

60. Public versus Private Addresses
Public IP addresses can be used on the Internet – registered with the Network Information Center
Private IP addresses cannot be used on the Internet (can be used internally – NAT)
Three address ranges set aside that can never be used on public networks: to to to

61. Automatic Private Internet Protocol Addressing (APIPA) Service
Bought and used by Microsoft operating systems
In home environment routers automatically set up NAT based off the IP addresses (like DHCP) assigned by windows
Acts as a failover in case there is a problem when trying to connect to an IP address range in some other way

62. Pulling NAT All Together
The picture illustrates APIPA – Automatic Private Protocol Addressing and private IP addresses.
Private IP addresses are on the computers – they are not allowed on the Internet.
The same IP addresses are part of the range that Microsoft uses for its Automatic Private IP Addressing Service. The person who set up the home network simply let Microsoft assign IP address as it saw it.
PAT (Port Address Translation) and SNAT (Source Network Address Translation) working together in this matter is called Networking Address Translation – NAT
PAT function: The router/switch assigns the port # to the private IPs: 25381, 25382, 25383
SNAT function: Keeps the same ports # attached to the public IP
NAT function: during the transmission translates to the proper IP addresses

63. Assigning IP Addresses
Static
IP addresses assigned to computers manually by the network administrator – he needs to make sure the address is unique
IP is not broadcasted, so it is more difficult to get by hackers
Dynamic
Dynamic Host Configuration Protocol (DHCP)
Allows to assign IP addresses dynamically without requiring constant input from network administrator

64. Network Segment with a DHCP Server and Clients
Once DHCP is set up on a DHCP server, IP addresses are automatically assigned to the clients as they come to the network or as their old addresses expire.
A DHCP server should be on the same segment as the clients.

65. DHCP Process
Assume that the DHCP server has been set up and configured correctly.
by broadcasting IP =
DISCOVER
OFFER
REQUEST
which includes IP address and the expiration time
ACK
and other DHCP servers on the segment
on the server term

66. Computer communicate with each other by using 3 methods:
Addressing Schemes
Computer communicate with each other by using 3 methods:
Unicast
Broadcast
Multicast
Sends a unicast packet only to the computer
that packet is intended to
A message is sent to all computers on
the network or segment:
- Client sends DHCPDISCOVER looking for DHCP server
- DHCP server accpts IP offered by client
- sends alert to all computers about a problem on the network
-the update on the state of router or other devices on the network
Is between unicast and broadcast.
Sends packets (the same info) to multiple computers but not all.
Ex: sends stream video to several computers
on the network at the same time

67. Summary
A physical address is the physical binary address every network device is given by its manufacturer; it is hard coded.
The physical address of a network device is 48 bits long and is made up of 1s and 0s.
Every computer on a network needs a unique logical address.
Subnetting breaks up an IP address range into smaller pieces so a given range of IP addresses can be used in more than one network.

68. Summary
Classful IP addressing is the classful method of determining what portion of an IP address is the network ID and what portion denotes hosts.
Classless Inter-Domain Routing (CIDR) is standard notation that indicates the network ID and host ID of an IP address.
IPv6 uses 128-bit IP addresses. Addresses are expressed in hexadecimal numbers, 32 numbers and letters, 0–9 and A–F.
The first 16 hexadecimal digits of an IPv6 address are the network ID, the last 16 digits the host ID.

69. Summary
In a broadcast domain, all devices on a network or a segment are connected together so they all receive the same broadcast signal from a computer.
In a collision domain, two or more devices on the same segment or network are able to cause their signal to interfere with the signal from another device on the same segment or network.
Supernetting is the process of combining several IP ranges, usually Class C ranges, into one larger network.

70. Summary
Network Address Translation (NAT) takes an IP address from an ISP or other location and uses that one IP address to allow all Internet-enable devices to which it is connected to access the Internet.
Static IP addresses are assigned manually.
Dynamic IP addresses are assigned automatically using Dynamic Host Configuration Protocol (DHCP).

71. Figure: IP addresses
Figure shows a part of an internet with two routers connecting three LANs.
Each device (computer or router) has a pair of addresses (logical and physical) for each connection.
In this case, each computer is connected to only one link and therefore has only one pair of addresses.
Each router, however, is connected to 3 networks (only two are shown in the figure).
So each router has 3 pairs of addresses, one for each connection.

72. Objectives Exam Objective Matrix Technology Skill Covered
Exam Objective Number
Physical Addressing
Classify how applications, devices, and protocols relate to the OSI model layers.
• MAC Address
Explain the purpose and properties of IP addressing.
• MAC address format
1.2
1.3
Logical Addressing
Classify how applications, devices, and protocols relate to the OSI
model layers.
• EUI-64
• Classes of addresses
• A, B, C and D
• Classless (CIDR)
• IPv4 vs. IPv6 (formatting)
• Subnetting

73. Objectives Exam Objective Matrix Technology Skill Covered
Exam Objective Number
How Physical and Logical Addressing Work Together
Explain the purpose and properties of IP addressing.
• MAC address format
Explain the purpose and properties of routing and switching.
• Broadcast domain vs. collision domain
1.3
1.4
Other Addressing Technologies
• Classes of addresses
• Public vs. Private
• Multicast vs. unicast vs. broadcast
• APIPA
Given a scenario, install and configure routers and switches.
• NAT
• PAT
Explain the purpose and properties of DHCP.
• Static vs. dynamic IP addressing
Given a scenario, install and configure a basic firewall.
• NAT/PAT
2.1
2.3
5.5