1. NETWORK LAYER IP Addressing 1

2. ANNOUNCEMENT: Rescheduled  NO PRACTICAL SESSIONS ON TUESDAY 22, November 2010  Rescheduled sessions: MONDAY: November 21, 2010, NW202  PRAC GROUP 1: 13.00 – 14.00 ---  PRAC GROUP 2: 15.00 – 16.00  PRAC GROUP 3: 16.00 – 17.00  PRAC GROUP 4: 17.00 – 18.00 2

3. Review - Local Area Networks  So far, we have only discussed local area networks (LAN),  Underlying physical medium is shared.  Data sent to a LAN goes to ALL of the computers on that LAN.  The size of LANs is limited. An electrical signal can only travel a limited distance. LAN size can be extended by using Repeaters 3

4. Review - Wide Area Network (WAN)  Network that covers large geographic area  A Wide Area Network (WAN) is made up from interconnected LANs  Network devices such as Switches or Routers can be used to join LANs together to form a WAN  Any examples?  Internet… 4 802.3 LAN Cat5 UTP WAN ISP Router

5. TCP/IP Protocol Stack  Two computers, anywhere in the world can communicate, even when not directly connected.  TCP/IP - a suite of protocols, is the reference model that provides specifications for the Internet  IP protocol operates at Layer 3 or Internet/ Network layer  TCP works at Layer 4 5 TCP IP Protocol

6. Network Layer  Network layer is responsible for moving data through a set of networks (Figure 1).  Router (R) helps to connect different networks together  A, B, C, D are different networks (Figure 1)  IP protocol operates at Network Layer  IP protocol uses IP Address to identify a PC uniquely in the Internet. 6 R R R - Router RR R R R Figure 1

7. Network Addressing: Analogy with telephone numbers 7  Network addresses are similar to Phone numbers  Area Code / Phone Number  831 – 479-5783  Network address helps to identify path (route) through network cloud from start to destination.  Each network (red ring in the figure 2) has an address 1.0 as 1 is the common number between 1.1, 1.2, 1.3  Each host (PC) within the network has an address (blue ring), e.g., 1.3 Router Figure 2 Figure 1

8. Why two Addresses for computer on network? Both Layer 2 (Ethernet) and Layer 3 (IP) Addresses are needed:  Layer 2 / MAC address  Physically burned into the NIC  Doesn’t change  The device’s real identity  Layer 3 / Protocol address  Configurable Can be changed  The device’s “mailing” address  Needs to change when device is moved connected to a network having different network address 8

9. Review: What is the MAC and IP Address on my computer? 9

10. Flat versus Hierarchical 10  Layer 2 - Flat addressing schemes  Next available  Social Security Number  MAC addresses  Layer 3 - Hierarchical addressing schemes  Phone numbers  ZIP codes  IP addresses

11. IP Addresses 11  Older Technology - Classful IP Addressing  Defines IP address as belonging to one of the available five classes: Class A Class B Class C Class D Class E  Current technology - Classless IP Addressing

12. IP Address 12 IP Addresses are 32 bits. Divide into four 8 bit sections (octets). Convert from binary to decimal.

13. Classful IP Addressing 13  Five different classes of IP addresses  A, B, C, D, E  Class A, B and C are primary classes Used for assigning IP addresses  Class D, E used for special purposes  Class D for multicast E.g., Videoconferencing  Class E addresses are reserved for experimentation

14. IP Address Classes 14 Network ID Host ID Network IDHost ID 8 16 Class A 32 Class B 10 Class C 110 Multicast Addresses Class D 1110 Reserved for experiments Class E 1111 248  Look at the first group of numbers in the dotted decimal notation  ClassRange  A0-127  B128-191  C192-223  D224-239  E240-255 Which Class has the largest Host ID and how many bits long? Which class has the largest Network ID and how many bits long?

15. Subnet mask - NetID /HostID boundary  Every machine on the network must know which part of the host address will be used as netid and hostid.  Subnet mask identifies the boundary between netid and hostid  Which class has more hosts?  Which class supports more networks?  Default subnet masks are  Class A : 255.0.0.0  Class B : 255.255.0.0  Class C : 255.255.255.0 15 Network Host Network Host Network Host 1st octet2nd octet3rd octet4th octet Class A Class B Class C

16. Find Network/Host ID from IP Address 16  Logical ‘AND’ IP address and subnet mask to get Net-ID.  E.g. IP address is 192.24.134.23, Find Network ID using default subnet mask of 255.255.255.0 for class C Find the binary representation of IP address and subnet mask Logical ‘AND’ with subnet mask 11000000.00011000.10000110.00010111 IP Address 11111111.11111111.11111111.00000000 Subnet mask for Class C 11000000.00011000.10001010.00000000 Network ID  Convert binary to decimal value  Network ID: 192.24.134.0 AND

17. 17 Hierarchy in IP addressing IP addresses are hierarchical. Conceptually each IP address is a pair Divided into a prefix and a suffix –Prefix (net-id) identifies network to which computers are attached. –Suffix (host-id) identifies computers within that network.

18. RD-CSY1017-07/08 18  Loopback address  127.0.0.0  Network address  IP address with all host bits set to 0 Example: 172.16.0.0, subnet mask:255.255.0.0  Broadcast address  IP address with all host bits set to 1 Example: 172.16.255.255, subnet mask:255.255.0.0 Special IP Addresses

19. RD-CSY1017-07/0819 Private IP Addresses  Private IP Addresses cannot exist on the public Internet.  Name Address Translation (NAT) used to give data packets a “legitimate” IP source address. Class B: 172.16.0.0 to 172.31.0.0 (In the 3 rd Octet, the 128, 64, and 32 bit are off. The 16 bit is on.) Class C: 192.168.0.0 to 192.168.255.0 (256 separate Class C Addresses) Class A: 10.0.0.0 (Favored by large enterprises because of its flexibility)

20. Grouping Devices into Networks and Hierarchical Addressing 20  Divide a large network into subnetworks  Geographical area  Functionality Departments Admin, HR…

21. IP addressing example 21 223.1.1.1 223.1.1.2 223.1.1.3 223.1.1.4 223.1.2.9 223.1.2.2 223.1.2.1 What is the class of IP address in the figure? Which network device is connecting the two networks?

22. Subnet Masks – Your Turn! 22  Underline the network portion of each address: Network Address Subnet Mask 172.0.0.0255.0.0.0 172.16.0.0255.255.0.0 192.168.1.0255.255.255.0 192.168.0.0255.255.0.0 192.168.0.0255.255.255.0 10.1.1.0/24 10.2.0.0/16 10.0.0.0/16  What is the other portion of the address?

23. Subnet Masks – Your Turn! 23  Underline the network portion of each address: Network Address Subnet Mask 172.0.0.0255.0.0.0 172.16.0.0255.255.0.0 192.168.1.0255.255.255.0 192.168.0.0255.255.0.0 192.168.0.0255.255.255.0 10.1.1.0/24 10.2.0.0/16 10.0.0.0/16  What is the other portion of the address?  Host Addresses