1. Page 1 Network Addressing CS.457 Network Design And Management

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3. Page 3 Two Key Network-Layer Functions

4. Page 4 Router Architecture Overview

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6. Page 6 IP Fragmentation & Reassembly

7. Page 7 IP datagram format CS.319 Computer Network

8. Page 8 Network Layer Functions Addressing –Each equipment on the path between source and destination must have an address –Internet Addresses –Assignment of addresses –Translation between network layer addresses and other addresses (address resolution)

9. Page 9 Types of Addresses

10. Page 10 Assignment of Addresses Application Layer address (URL) –For servers only (clients don’t need it) –Assigned by network managers and placed in configuration files. –Some servers may have several application layer addresses Network Layer Address (IP address) –Assigned by network managers, or by programs such as DHCP, and placed in configuration files –Every network on the Internet is assigned a range of possible IP addresses for use on its network Data Link Layer Address (MAC address) –Unique hardware addresses placed on network interface cards by their manufacturers ( based on a standardized scheme) –Servers have permanent addresses, clients usually do not

11. Page 11 Internet Addresses Managed by ICANN –Internet Corporation for Assigned Names and Numbers –Manages the assignment of both IP and application layer name space (domain names) Both assigned at the same time and in groups Manages some domains directly (e.g.,.com,.org,.net) and Authorizes private companies to become domain name registrars as well Example: kasem bundit university –IP addresses of kbu.ac.th is 203.149.0.3,

12. Page 12 IPv4 Addresses 4 byte (32 bit) addresses –Strings of 32 binary bits Dotted decimal notation –Used to make IP addresses easier to understand for human readers Breaks the address into four bytes and writes the digital equivalent for each byte

13. Page 13 Classfull Adressing

14. Page 14 Subnets

15. Page 15 Subnets: Example

16. Page 16 Subnet Masks Used to make it easier to separate the subnet part of the address from the host part. Example –Subnet: 149.61.10.x –Subnet mask: 255.255.255.0 or in binary 11111111.11111111.11111111.00000000 Example –Subnets: 149.61.x.x –Subnet mask 255.255.0.0 or, in binary: 11111111.11111111.00000000.00000000

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18. Page 18 Network and Host Addresses

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20. Page 20 A Network with Two Levels of Hierarchy

21. Page 21 A Network with Three Levels of Hierarchy

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23. Page 23 IP addresses

24. Page 24 Dynamic Addressing

25. Page 25 Programs for Dynamic Addressing Bootstrap Protocol (bootp) Dynamic Host Control Protocol (DHCP) Different approaches, but same basic operations: –A program residing in a client establishes connection to bootp or DHCP server –A client broadcasts a message requesting an IP address (when it is turned on and connected) –Server (maintaining IP address pool) responds with a message containing IP address (and its subnet mask) –IP addresses can also be assigned with a time limit (leased IP addresses) –When expires, client must send a new request

26. Page 26 DHCP: Dynamic Host Configuration Protocol

27. Page 27 DHCP client-server scenario

28. Page 28 DHCP client-server scenario

29. Page 29 Handling IP Address Depletion Variable Length Subnet Mask (VLSM)and Classless Interdomain Routing (CIDR) Network Address Translation (NAT) IPv6

30. Page 30 CIDR: Classless InterDomain Routing subnet portion of address of arbitrary length address format: a.b.c.d/x, where x is # bits in subnet portion of address

31. Page 31 Q : How does network get subnet part of IP address?

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33. Page 33CS.319 Computer Network

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35. Page 35 Hierarchical addressing: route aggregation

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37. Page 37CS.319 Computer Network

38. Page 38 NAT: Network Address Translation Motivation: local network uses just one IP address as far as outside world is concerned: –range of addresses not needed from ISP: just one IP address for all devices –can change addresses of devices in local network without notifying outside world –can change ISP without changing addresses of devices in local network –devices inside local net not explicitly addressable, visible by outside world (a security plus).

39. Page 39 NAT : Network Address Translation Assign private addresses to the internal systems Router translate the addresses

40. Page 40 NAT: Network Address Translation

41. Page 41 NAT: Network Address Translation

42. Page 42 Using Illegal Addresses with NAT

43. Page 43 IPv6 is… IP with: –Larger address fields (128 bits) –Yes, that’s a VERY big number! –Smaller number of header fields –Altered support for header extensions –Addition of a flow label header field

44. Page 44 IPv6 What has not changed –Almost everything! –IPv6 is a connectionless datagram delivery service using end-to-end address identifiers and end-to-end signalling with TCP and UDP transport services. So is IPv4.

45. Page 45 IPv6 Strengths Larger Addresses mean no forced Network Address Translators –Eliminate NAT architectures as a means of address scaling –Allow coherent end-to-end packet delivery –Improve the potential for use of end-to-end security tools for encryption and authentication –Allow for widespread deployment peer-to-peer applications SIP, IMM, …

46. Page 46 What’s good about IPv6 Larger Address space –128 bit: 3.4 ื 10^38 IPv6 can not easily solve (same as IPv4); –(Security,Multicast,Mobile,QoS) Re-design to solve the current problems such as; –Routing –Security –Auto-configuration –Plug & Play

47. Page 47 IPv6 Initial motivation: 32-bit address space soon to be completely allocated. Additional motivation: –header format helps speed processing/forwarding –header changes to facilitate QoS IPv6 datagram format: –fixed-length 40 byte header – no fragmentation allowed

48. Page 48 IPv6 Header (Cont)

49. Page 49 Ipv6 and IPv4 Header Format

50. Page 50 IPv6 Address

51. Page 51 IPv6 address notation Basic rules “:” in every 2 bytes,Hex digits example 3ffe:0501:0008:0000:0260:97ff:fe40:efab –3ffe:501:8:0:260:97ff:fe40:efab –3ffe:501:8::260:97ff:fe40:feab ff02:0000:0000:0000:0000:0000:0000:0001 –ff02:0:0:0:0:0:0:1 –ff02::1

52. Page 52 Transition From IPv4 To IPv6 Not all routers can be upgraded simultaneous –no “flag days” –How will the network operate with mixed IPv4 and IPv6 routers? Tunneling: IPv6 carried as payload in IPv4 datagram among IPv4 routers

53. Page 53 Tunneling

54. Page 54 Tunneling

55. Page 55 Tunneling

56. Page 56 Question ?