1. IP Protocol - Introduction Dr. Farid Farahmand

2. Introduction TDM transport networks are not sufficient for data communications Low utilization TDM networks are being replaced by packet/frame/cell based data communication systems So the question is what are such communication systems and protocols?

3. Transport Protocol Classification Any communication system provides its services in two basic ways Dedicated lines (circuits) Shared lines (circuits) In packet/frame based technologies, shared resources are categorized as Connection oriented Multiple predefines virtual paths are established through the same physical link (highway system) The virtual path can be Permanent: logical circuit provisioned as the system us turned-up Switched: Logical circuit established upon request Connectionless No predefined path exists; routing takes place based on the source and destination nodes (airplane system)

4. Network Basics The backbone or core network Consists of switches, core routers, Gateway routers (maybe called Differently) Edge routers are used to be connected to the core network Data path Ingress Edge node Egress Edge node

5. Transport Layer End-to-end delivery of the entire message. Differs from network layer that oversees end-to-end delivery of individual packets without recognizing any relationship between them. Addressing We have seen that in the Internet the top three OSI layers are combined into the application layer. On the Internet, the transport layer interacts with applications. Because many applications (and application instances - - windows) can be active at any one time, this requires an additional layer of addressing known as port addressing

6. Transport Layer – Port Address

7. Connectionless vs. Connection-Oriented

8. Connectionless Services There is no error control, so incorrect frames are simply discarded. This is called a best try service. Commonly used for low error rate lines. The Internet model network layer protocol, IP, is a connectionless service. UDP is the Internet model transport layer protocol. Connection-oriented Services Involves negotiating a ‘link’ between the source and destination. This link will be a virtual connection in a switched network. Since a single pathway is established, the acknowledgement process for error control is facilitated. These services are considered reliable and therefore are the most frequently used. There is no connection-oriented network layer protocol in the Internet model. TCP is the connection-oriented transport layer protocol in the Internet model.

9. Functions of a Connection-Oriented Transport Protocol Connection establishment Reliable delivery: error control (similar to data link) sequence control; loss control; duplication control (discard duplicated) Flow control Connection termination

10. Functions of a Connection- Oriented Transport Protocol Connection Termination Three way hand shake

11. Functions of a Connection- Oriented Transport Protocol Flow control Flow control similar to that used by the data link layer, however, the flow control is from end-to-end.

12. Transmission Control Protocol (TCP) Connection oriented transport protocol that provides all the functionality defined for the transport layer in the OSI model. Packets are called segments: -16 bits are allowed for port addresses (numbers) in both protocols (allows for up to 65536 ports!) -TCP source and destination

13. User Datagram Protocol (UDP) UDP provides a connectionless service with limited error control. No sequence numbers implies that sequence, loss and duplication control are not supported. Packets are called datagrams: RTP (real-time protocol) header contains field used to assist UDP in transmitting real-time traffic such as VoIP

14. IP Protocol IPv4 Addresses are 32 bits wide Its header is 20 bytes at minimum Uses doted-decimal notation (e.g. 43.23.43.56) IPv6 Provides larger address domain; addresses are 128 bits wide Multiple separate headers are supported Handles audio and video; providing high quality paths Supports unicast, multicast, anycast

15. IP Header The IP datagram contains data and IP address The IP datagram is encapsulated in a frame with physical address The header changes as the frame goes from one network domain to the next IP Datagram Frame DataIP Address Frame Address

16. IP Packet Format +0 - 34 - 78 - 1516 - 1819 - 31 0VersionHeader lengthType of ServiceTotal Length 32IdentificationFlagsFragment Offset 64Time to LiveProtocolHeader Checksum 96Source Address 128Destination Address 160Options 192 Data All numbers are in bits

17. IP Packet Format +0 - 34 - 78 - 1516 - 1819 - 31 0VersionHeader lengthType of ServiceTotal Length 32IdentificationFlagsFragment Offset 64Time to LiveProtocolHeader Checksum 96Source Address 128Destination Address 160Options 192 Data All numbers are in bits Internet header Length Reliability/ TH/delay How long in seconds pkt stays in Internet Next higher level protocol after IP

18. IP Packet Format - TTL TTL (time-to-live) refers to the number of router hops (or seconds) the IP packet is allowed before it must be discarded. Each router that receives a packet subtracts one from the count in the TTL field. When the count reaches zero, the router detecting it discards the packet and sends an Internet Control Message Protocol (ICMP) message back to the originating host.

19. Encapsulated IP Packet in Ethernet Frame MAC and Associated IP address Ethernet Frame Carrying IP Packet

20. Protocol Analyzer Display: 000000 00 C0 A0 51 24 00 C0 93 21 88 A7 08 00 45 08 0010 00 5A DC 28 00 00 FF 01 88 08 C0 99 B8 01 C0 99 0020 B8 03 2a B4 DD ….. Encapsulated IP Packet in Ethernet Frame Ethernet Frame Carrying IP Packet IP starting with 45 Hex indicates IPv4 with standard length of 20 bytes IP starting with 4F Hex indicates IPv4 with standard length of 60 bytes Remember: 2 4 =16; 45= 0100 0101= One Byte An Ethernet frame containing IP information has 08 00 in its type field 99 is one byte 1001 Example:

21. IP Addressing Two address types Physical address (the frame has the physical address) Embedded in the hardware (NIC, e.g., 00 00 11 00 11 33) Also called the Media Address Control (MAC) address Logical IP datagram contains the logical IP address To transport IP packets both physical and IP addresses must be known ARP (address resolution protocol) and RARP (reverse) address resolution protocol are used to convert MAC to IP address and vice versa Static address resolution Dynamic address resolution

22. IP Addressing Uses doted-decimal notation A network address is divided into Netid and Hostid IP Address classification (number of hosts per network) ClassLeading bitsNetwork Address (Netid) Host Address (Hostid) Class A 0 7 bit (125) * 24 bit (16,777,151,750) Class B 10 14 bit (16,368) 16 bit (65,534) Class C 110 21 bit (2,096,896) 8 bit (254) Class D (multicast) 1110 Class E (reserved) 1111 * Some values are reserved!

23. IP Addressing Classification Network AddressHost Address Network Address Host Address Network Address Host Address Reserved for Internet research Multicast Address

24. Example of IP Addressing Q1: Determine the network address for the following IP addresses: 1- 84.42.58.11 (84 = 54 Hex = 0101 0100)  Netid=84.0.0.0  Class A  Hostid=0.42.58.11 2- 144.54.67.5 (144 = 90 Hex = 1001 0000)  Netid=144.62.0.0  Class B  Hostid=0.0.67.5 Q2: What type of IP address classification will a large organization with 1000 individual users in 150 dispersed buildings use?  Class B

25. IP Routing Protocols Routing packets requires having knowledge about the network Partial (know your own neighbors) Full (know the entire network elements) Retrieving network information (network discovery protocols) RIP (routing information protocol): routing based on the least number of hops OSPF (open shortest path first): Routing based on number of hops, link speed, congestion

26. Sources Tomasi Text Book Comer Text book