Network Addressing

1. Network Addressing CS.457 Network Design And Management

3. Two Key Network-Layer Functions

4. Router Architecture Overview

6. IP Fragmentation & Reassembly

7. IP datagram format CS.319 Computer Network

8. 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) Network Layer Functions

9. Types of Addresses

10. 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 Assignment of Addresses

11. 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, Internet Addresses

12. 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 IPv4 Addresses

13. Classfull Adressing

14. Subnets

15. Subnets: Example

16. 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 Subnet Masks

18. Network and Host Addresses

20. A Network with Two Levels of Hierarchy

21. A Network with Three Levels of Hierarchy

23. IP addresses

24. Dynamic Addressing

25. 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 Programs for Dynamic Addressing

26. DHCP: Dynamic Host Configuration Protocol

27. DHCP client-server scenario

28. DHCP client-server scenario

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

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

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

33. CS.319 Computer Network

35. Hierarchical addressing: route aggregation

37. CS.319 Computer Network

38. 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). NAT: Network Address Translation

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

40. NAT: Network Address Translation

41. NAT: Network Address Translation

42. Using Illegal Addresses with NAT

43. 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 IPv6 is…

44. 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. IPv6

45. 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, … IPv6 Strengths

46. Larger Address space 128 bit: 3.4ื10^38 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 What’s good about IPv6

47. 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 IPv6

48. IPv6 Header (Cont)

49. Ipv6 and IPv4 Header Format

50. IPv6 Address