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Network Addressing

Network Addressing. Lesson 4. Objectives. Objectives. 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 address Physical address of a network device is 48 bits long

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Network Addressing

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  1. Network Addressing Lesson 4

  2. Objectives

  3. Objectives

  4. 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 address • Physical address of a network device is 48 bits long • Made up of 1s and 0s • Physical address generally expressed in hexadecimal format

  5. Physical Addressing (Continued) • Hexadecimal • 91-FC-5D-D9-A3-B0 • Binary: • 100100011111110001011101110110011010001110110000 • First 24 bits is Organizationally Unique Identifier • Last 24 bits is host portion

  6. 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 • IPv6 can use EUI-64 to create a unique interface identifier

  7. MAC Addressing • Refers to the function of the physical address, while the term “physical address” more often refers to the actual thing • 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

  8. Spoofing MAC Addresses • 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

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

  10. 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 • 11000000100000101110001100011011 expressed in 8-bit decimal format as 192.130.227.27 • 4 billion addresses in IPv4 address space, but have all been used

  11. 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

  12. 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 255.255.255.0,binary equivalent is11111111111111111111111100000000

  13. 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

  14. ANDing Example • Result of ANDing 192.130.227.27 with the subnet mask 255.255.255.0

  15. 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

  16. IP Address Classes and Some Defining Characteristics

  17. IP Ranges Set Aside for Various Uses

  18. Classless IP Addressing • Host and network portions of an IP address based on the subnet mask • The class of an IP address not considered • Example: IP address 192.130.227.27 • If subnet mask = 255.0.0.0, then 192 is network and the rest host • If subnet mask = 255.255.0.0, then network portion is 192.130 and host portion is 227.27

  19. Classless Inter-Domain Routing (CIDR) • Standard notation that indicates network ID and host ID of an IP address • Format is similar to 192.130.227.27/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

  20. CIDR Examples • 192.130.227.27/8 indicates the subnet mask is 255.0.0.0 • 192.130.227.27/16 indicates the subnet mask is 255.255.0.0 • 192.130.227.27/24 indicates the subnet mask is 255.255.255.0

  21. 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:

  22. Binary Conversion—Base 2 Example • Binary value 11100011 in base 2 number system out to 8 bits • Add decimal values that have a 1 under them: 128 + 64 + 32 + 2 + 1 = 227

  23. Converting Decimal to Binary Example • 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

  24. Converting Decimal to Binary Example (Cont.) • 130 – 128 = 2 • The smallest number that can be successfully subtracted from 2 is 2, so place a 1 in row 3 under the “2”

  25. Converting Decimal to Binary Example (Cont.) • 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 10000010

  26. Determine Subnet Mask Using CIDR • Example: CIDR notation is 192.130.227.27/12 • 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

  27. Determine Subnet Mask Using CIDR (Cont.) • 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 = 11110000 • Enter into table, value converts to 240

  28. Determine Subnet Mask Using CIDR (Cont.) • 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 192.130.227.27/12 is therefore 255.240.0.0

  29. 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

  30. Values in Subnetting Class C Subnets

  31. Value Changes by Increments of 64 in the Last Octet of 207.253.187.0/26

  32. Absolute Network Ranges UsingCIDR 207.253.187.0/26

  33. Usable Network Ranges from All Usable Networks, Using CIDR 207.153.187.0/26

  34. Values in Subnetting Class C Subnets

  35. The 207.253.187.0/27 Network

  36. Internet Protocol Version 6 (IPv6) • Uses 128-bit IP addresses • Addresses expressed in hexadecimal numbers • 32 numbers and letters, 0–9 and A–F • First 16 hexadecimal digits are network ID, last 16 hexadecimal digits are host ID • Example: 13D4:FA97:0000:1258:AD8B:1009:34D6:1800 • No subnetting needed

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

  38. IPv6 Address Double Colon Technique • Not all 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

  39. EUI-64 • Host can automatically assign itself a unique 64-bit interface identifier • Two steps: • Divide MAC address 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

  40. 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 • Result is a Modified EUI-64 address • Can be used by IPv6 as a unique interface identifier on a device connected to a network

  41. 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

  42. Simplified Form of an internetwork

  43. Internetwork with Letters Representing MAC Addresses

  44. 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

  45. Different Segments or Collision Domains of the Internetwork

  46. Segments Need Unique Logical Addresses • Each network segment requires a unique network or logical address, represented by an IP address

  47. Internetwork Segments with Unique Logical Addresses

  48. Devices Need Unique Logical Addresses • Each network interface 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

  49. Internetwork Segments with Unique Logical Addresses Assigned to Each Device

  50. Source Computer and Its Intended Destination in Internetwork

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