ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 ICT 6621 Advanced Networking Course Teacher Dr. Khaled Mahbub Assistant Professor, IICT, BUET

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Course Information Structure –14 week of lectures –2 mid-term exams (one hour each, ) - Mid-term 1, in 5 th /6 th week (30% of course marks) - Mid-term 2, in 10 th /11 th week (30% of course marks) –Final exam after 14 weeks of classes (40% of course marks) Recommended textbooks : oText1 - “TCP/IP Illustrated, Volume 1: The protocols”, by W. Richard Stevens, Publisher: Addison Wesley oText2 – “Computer Networks”, 4 th edition, by Andrew S. Tanenbaum, Publisher: Prentice Hall oText3 – “Computer Networking: A Top-Down Approach Featuring the Internet”, 3 rd edition, by James F. Kurose and Keith W. Ross, Publisher: Addison Wesley oAdditional materials will be suggested as needed.

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Resources Lecture slides and the textbooks can be downloaded from the following page Lecture slides will be uploaded after each class, and it will stay there for next 2 weeks. The e-copies of the books will stay there for the first 3 weeks.

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Course Outline The TCP/IP protocol stack: IP, ARP, TCP and UDP, DNS, ICMP, Internet addressing, routing, IP multicast, RSVP, Next Generation IP, Interior gateway protocols: RIPv2,IGRP, EIGRP, OSPF; Wireless: Radio basics, satellite systems, WAP, current trends, issues with wireless over TCP; Congestion Control: control, avoidance, control and avoidance algorithms, congestion in the Internet; Network Security: IP security, firewalls; Management: Quality of service (QoS), network vs. distributed systems management, integrated service, differentiated service, protocols, web-based management.

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Today’s Outline Review of Computer Network Basics.

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Computer Network & Internet Computer Network: Interconnected collection of autonomous computers and other devices. Internet: network of networks local ISP company network regional ISP router workstation server mobile

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Types of Networks Local Area Networks (LAN) are generally privately owned networks. –restricted in size, i.e. within a single building or campus of up to a few kilometers in size. –Traditionally uses a transmission technology consisting of a cable to which all machines are attached –Various topologies are possible, e.g. Bus, Ring. Metropolitan Area Networks (MAN) covers a city or town. Wide Area Networks (WAN) spans a large geographical area, e.g. a country or continent. –Collection of machines (hosts) are connected by subnet(s) –Subnets are composed of (i) transmission lines (e.g. copper wire, optical fiber or radio links) that move bits between machines and (ii) switching elements (specialized computers, known as router) that connect three or more transmission lines. Wireless Networks –e.g., System interconnection, wireless LANs, wireless WANs, not necessarily mobile Internetworks (or Internet) connect different networks. –Incompatible networks are connected by means of machines called gateway that provide necessary translation (both h/w and s/w).

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 What’s a protocol human protocols: “what’s the time?” “I have a question” introductions … specific msgs sent … specific actions taken when msgs received, or other events network protocols: machines rather than humans all communication activity in Internet governed by protocols

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Protocol Example Hi Got the time? 2:00 TCP connection req TCP connection response Get time Time Request: Human Protocol URL Request: Network Protocol

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Protocols A protocol defines: –the format and the order of the messages exchanged –the syntax, semantics, and actions on receipt/transmission of a message Why use protocols? –to provide a common language –rules must be unambiguous and followed exactly

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Network Software Network software is highly structured and are organized as a stack of layers or levels. Layered structure is used to deal with complex systems, –explicit structure allows identification, relationship of complex system’s pieces layered reference model for discussion –modularization eases maintenance, updating of system change of implementation of layer’s service transparent to rest of system

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Protocol Stack Layer n on one machine interacts with layer n on another machine. The rules and conversations used in this interaction are collectively known as the layer n protocol. A set of layers and protocols is called a network architecture. A list of protocols used by certain system, one protocol per layer, is called a protocol stack.

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 The protocol stack OSI (7 layers): proposed by ISO in 1983 as first step toward international standardization of protocols TCP/IP (4 layers): proposed by DARPA in 1970 as a specification for computer network protocols

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 TCP/IP protocol stack Each layer’s responsibility: –The link layer (data-link layer, network interface layer) handle all the hardware details and interaction of physical devices (e.g. cables, network cards) –The network layer (internet layer) handles the movement of packets around the network –The transport layer provides a flow of data between two hosts, for the application layer above TCP => provides a reliable flow of data between two hosts UDP => unreliable, reliability must be added by the application layer –The application layer handles the details of the particular application

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 TCP/IP protocol stack

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 TCP/IP protocol stack Two networks connected with a router

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 TCP/IP Layering Various protocols at the different layers in TCP/IP protocol suite

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 IP address and port numbers Every host on a network is identified by a unique number, called IP address. IP address is a 32 bit number and this number is written in dotted decimal notation, i.e. four decimal numbers one for each byte. E.g Applications in the application layer are identified by unique numbers, called port numbers. Some well known port numbers are, – FTP server is on TCP port 21 – Telnet server is on TCP port 23 – TFTP is on UDP port 69 – Rlogin is on TCP port 513

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Encapsulation message segment datagram frame

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Encapsulation example Encapsulation of data as it goes down the protocol stack

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Demultiplexing The demultiplexing of a received Ethernet frame

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Client-Server Model Typical network application has two pieces: client and server –Client: initiates contact with server (“speaks first”) typically requests service from server, for Web, client is implemented in browser; for e- mail, in mail reader –Server: provides requested service to client e.g., Web server sends requested Web page, mail server delivers

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Client-Server Model Two classes of servers –iterative I1. Wait for a client request to arrive I2. Process the client request I3. Send the response back to the client that send the request I4. Go back to step I1 –concurrent C1. Wait for a client request to arrive C2. Start a new server to handle this client’s request. This may involve creating a new process, task, or thread, depending on the operating system. This new server handles this client’s entire request. When complete, this new server terminates C3. Go back to step C1

ICT 6621 : Advanced NetworkingKhaled Mahbub, IICT, BUET, 2008 Reading Material Chapter 1 – text1 (Stevens) Chapter 1 – text2 (Tanenbaum)