Business Data Communications and Networking 11 th Edition

Business Data Communications and Networking 11 th Edition Jerry Fitzgerald and Alan Dennis John Wiley & Sons, Inc Ahmed Imran Kabir, Adjunct Lecturer School of Business and Economics United International University 2 -1

Chapter 5 Network and Transport Layers

Announcements and Outline Assessment 1 Review Assignment – Due 2/15 Assessment 1 – 2/17 (multiple choice and short answer) Recap 4 Data Link Layer 4. 1 Media Access Control 4. 2 Error Control 4. 3 Data Link Protocols Outline 5 Network and Transport Layers 5. 1 Protocol 5. 2 Transport Layer Functions 5. 3 Addressing 5. 4 Routing 5. 5 TCP/IP Example Copyright 2010 John Wiley & Sons, Inc 3 3

Chapter 5 Outline Transport & Network Layer Protocols § TCP/IP Transport Layer Functions § Segmenting § Linking to the Application Layer § Session management Addressing § Assigning addresses and address resolution Routing § Types of routing, routing protocols, and multicasting TCP/IP Examples 44

Network Layers Computer 1 Computer 2 5 5

Introduction Transport and Network layers § Responsible for moving messages from end-to-end in a network § Closely tied together § TCP/IP: most commonly used protocol • Used in Internet • Compatible with a variety of Application Layer protocols as well as with many Data Link Layer protocols Application Layer Transport Layer Network Layer Data Link Layer 6 6

Transport/Network Layer Protocols TCP/IP (Transmission Control Protocol / Internet Protocol) § Most common, used by all Internet equipment Developed in 1974 by V. Cerf and B. Kahn § As part of Arpanet (U. S. Department of Defense) Most common protocol suite § Used by the Internet § Largest percentage of all backbone, metropolitan, and wide area networks use TCP/IP § Most commonly used protocol on LANs 7 7

Introduction - Transport layer Responsible for end-to-end delivery of messages Application Layer Responsible for segmentation and reassembly Transport Layer § Breaking the message into several smaller Network Layer pieces at the sending end § Reconstructing the original message into a single whole at the receiving end Interacts with Application Layer 8 8

Transmission Control Protocol (TCP) used in message reassembly TCP Header: 192 bits (24 bytes) 5 -9

Introduction – Network Layer Responsible for addressing and routing of messages § Selects best path from computer to computer until the message reaches destination Transport Layer Performs encapsulation on sending end § Adds network layer header to message segments Network Layer Data Link Layer Performs decapsulation on receiving end § Removes the network layer header at receiving end and passes them up to the transport layer 10 10

Internet Protocol (IP) Two versions in current in use 11 11

IP Packet Formats: IPv 4 (24 bytes) vs. IPv 6 (40 bytes) IPv 4 Header: 192 bits (24 bytes) IPv 6 Header: 320 bits (40 bytes) 5 - 12

Student Questions What goes in the data field of an IP Packet in the Network Layer? What about the previous layer’s packet? https: //db-ip. com/ 13 13

TCP/IP’s 5 -Layer Network Model 14 14

Efficiency You want to transmit a 500 byte email message. What would be the efficiency in transmitting this message? Overhead: • SMTP: • TCP: • IP: • Ethernet: What about an HTTP file of 4000 bytes? 15 15

Transport Layer Functions Segmenting Application Layer Linking to the Application Layer Transport Layer Session management Network Layer § § § 16 16

5. 2. 1 Segmenting Breaking outgoing messages from the application layer into a set of smaller segments for transmission through network. When the transport layer is set up, it determines what size segments will make best use of its data link protocols. 17 17

Packetization and Reassembly sender What size packet to use? FTP TCP IP IP receiver Delivers incoming packets as they arrive (e. g. , Web pages) or to wait until entire message arrives (e. g. , e-mail) 18 18

5. 2. 2 Linking to Application Layer TCP may serve several Application Layer protocols at the same time § Problem § Solution How do we know what number the server uses? HTTP FTP SMTP 80 21 TCP 25 What would be the other type of number used and why? 5 - 19 …

5. 2. 2 Application Layer Services 5 - 20

5. 2. 3 Session Management A session can be thought of as a conversation between two computers. Types of Session Management • Connection Oriented • Connectionless Routing • Quality of Service (Qo. S) 5 - 21

5. 2. 3. 1 Session Management - Connection Oriented Setting up a virtual circuit, or a TCP connection § Packet deliveries are acknowledged For which application layer packets does the transport layer use a connection oriented session for? 5 - 22

5. 2. 3. 1 Setting up Virtual Connections B A SYN Data 1 Data 2 ACK 2 Data 3 Data 4 FIN not busy 5 - 23

5. 2. 3. 2 Session Management - Connectionless Routing • Provided by UDP § Sending packets individually without a virtual circuit § Each packet is sent independently of one another, and will be routed separately, following different routes and arriving at different times 5 - 24

5. 2. 3. 2 UDP - User Datagram Protocol used for connectionless routing in TCP/IP suite that uses no acks, no flow control Uses only a small packet header § Only 8 bytes containing only 4 fields: • Source port • Destination port • Message length • Header checksum Can also be used for applications where a packet can be lost, such as information rich video 5 - 25

5. 2. 3. 3 Protocols Supporting Qo. S Asynchronous Transfer Mode (ATM) § A high-speed data link layer protocol RSVP TCP/IP protocol suite RTSP RTP § Resource Reservation Protocol (RSVP) • Sets up virtual circuits for general UDP purpose real-time applications § Real-Time Streaming Protocol (RTSP) IP • Sets up virtual circuits for audio-video applications § Real-Time Transport Protocol (RTP) • Used after a virtual connection setup by RSVP or RTSP • Adds a sequence number and a timestamp for helping applications to synchronize delivery • Uses UDP (because of its small header) as transport 5 - 26

Network Layer Functions Addressing § Each device on the path between source and destination must have an address § Internet Addresses Transport Layer § Assignment of addresses § Translation between network layer Network Layer addresses and other addresses (address resolution) Data Link Layer Routing § Process of deciding what path a packet must take to reach destination § Routing protocols 5 - 27

5. 3. 1 Types of Addresses • Application Layer Address Application Layer • Network Layer Address Transport Layer Network Layer Data Link Layer • Data Link Layer Address 5 - 28

5. 3. 1 Types of Addresses Address Type Example Address Analogy Application Layer URL www. iub. edu Name Network Layer IP address 129. 79. 127. 4 (4 bytes) Zip code Data Link Layer MAC address 00 -0 C-00 -F 5 -03 -5 A (6 bytes) Street address • These addresses must be translated from one type to another for a message to travel from sender to receiver. • This translation process is called address resolution. 5 - 29

5. 3. 1 Question: Addresses and Clients How many addresses are assigned to the different computers in this room? § Desktop § Laptop 5 - 30

5. 3. 2 Assignment of Addresses Data Link Layer Address (MAC address) § Unique hardware addresses placed on network interface cards by their manufacturers ( based on a standardized scheme) How are these set? What do you they look like? http: //www. coffer. com/mac_find/ 5 - 31

5. 3. 2 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 5 - 32

5. 3. 2 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: UNCW § URL that end in. uncw. edu § IP addresses in the 152. 20. x. x range (where x is any number between 0 and 255) 5 - 33

5. 3. 2 How do you decide who gets what address? Group of computers on the same LAN with IP numbers using the same prefix Assigned addresses § For example: • Subnet 152. 20. 234. x – Computers in CIS labs (x is between 0 & 255) • Subnet 152. 20. 244. x & 152. 20. 196. x – Computers in CIS Offices (x is between 0 & 255) • Subnet 129. 79. 125. x – Computers in Cameron Does anyone see a problem with the subnets above? 5 - 34

5. 3. 2 Subnets: Example 5 - 35

5. 3. 2 Subnets How do you think UNCW handles assigning address? How does the server know where to send the IP address if it doesn’t have one? 5 - 36