Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 1 Cisco Systems CCNA Version 3 Semester 1 Module 11

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 2 Students completing this module should be able to: Describe the functions of the TCP/IP transport layer. Describe flow control. Describe the processes of establishing a connection between peer systems. Describe windowing. Describe acknowledgment. Identify and describe transport layer protocols. Describe TCP and UDP header formats. Describe TCP and UDP port numbers. List the major protocols of the TCP/IP application layer. Provide a brief description of the features and operation of well-known TCP/IP applications.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 3 The Department of Defense (DoD) developed the TCP/IP reference model to provide a communication network that could continue to function in wartime. Transport Layer

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 4 OVERVIEW 11.1 TCP/IP Transport Layer Introduction to transport layer Flow control Session establishment, maintenance, and termination overview Three-way handshake Windowing Acknowledgment Transmission Control Protocol (TCP) User Datagram Protocol (UDP) TCP and UDP port numbers 11.2 The Application Layer Introduction to the TCP/IP application layer DNS FTP HTTP SMTP SNMP Telnet

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Introduction to transport layer Segmentation of upper-layer application data Establishment of end-to-end operations Transport of segments from one end host to another end host Flow control provided by sliding windows Reliability provided by sequence numbers and acknowledgments MAC d MAC s IP s IP d P s P d P s P d

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 6 MAC d MAC s IP s IP d P s P d Reliable connection-oriented Introduction to transport layer

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Introduction to transport layer Peer to Peer Communication is really communication between the headers at each layer. Layers 2 and 3 are best effort or connectionless. Layer 4 Transport is connection oriented. The ‘connection’ is in the header.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Introduction to transport layer

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Flow control

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Introduction to transport layer There may be more than one application using the TCP/IP stack at the same time. Port Numbers are used to keep them separate. HTTP 80 TELNET 23 SMTP 25 DNS 53

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Session establishment, maintenance, and termination overview HTTPTELNETDNS TELNET 23 FTP 21 Congestion can be caused by: Faster computers generate traffic volume greater than the network is able to transfer. Large numbers of computers send data to the same location at the same time.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Session establishment, maintenance, and termination overview

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Session establishment, maintenance, and termination overview

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Three-way handshake

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 15 In TCP the three-way handshaking process begins when the sending host sends a SYN segment.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Windowing

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Acknowledgment

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide – 6267 = 336 bytes or octets

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Windowing

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 20 I can accept a window this big. Source Port = 80. my Host. Destination Port = Marc’s server. Window size is the size in Octets or Bytes that the device with the Source Port Transport Layer buffer is ready to accept. This is Flow Control.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Acknowledgment The source must receive an "ACK 4" acknowledgement before sending more data.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 22

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Transmission Control Protocol (TCP) 567 bytes or octets of data.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide bytes or octets of data.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 25 In TCP the three-way handshaking process begins when the sending host sends a SYN segment. Source = 3550 Destination = 80 1

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 26 The Destination ACK… Source = 80 Destination = 3550 … and requests a SYN of its own. 2

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 27 The Source acknowledges. Source = 3550 Destination = 80 3

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 28 Source port – Number of the calling port Destination port – Number of the called port Sequence number – Number used to ensure correct sequencing of the arriving data Acknowledgment number – Next expected TCP octet HLEN – Number of 32-bit words in the header Reserved – Set to zero Code bits – Control functions, such as setup and termination of a session Window – Number of octets that the sender is willing to accept Checksum – Calculated checksum of the header and data fields Urgent pointer – Indicates the end of the urgent data Option – One option currently defined, maximum TCP segment size Data – Upper-layer protocol data

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide User Datagram Protocol (UDP) no guaranteed delivery of datagrams reliability provided by the application layer connectionless Source port – Number of the calling port Destination port – Number of the called port Length – Number of bytes including header and data Checksum – Calculated checksum of the header and data fields Data – Upper-layer protocol data

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide TCP and UDP port numbers You should at least remember these port numbers.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide TCP and UDP port numbers

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide TCP and UDP port numbers

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide TCP and UDP port numbers Numbers below 1024 are considered well-known port numbers. Numbers above 1024 are dynamically assigned port numbers. Registered port numbers are those registered for vendor-specific applications. Most of these are above is 10 bits. There are 16 bits (65,536) available for port numbers All zeros in the first six positions means it is a “well-known” port number.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide TCP and UDP port numbers

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 35 OVERVIEW 11.1 TCP/IP Transport Layer Introduction to transport layer Flow control Session establishment, maintenance, and termination overview Three-way handshake Windowing Acknowledgment Transmission Control Protocol (TCP) User Datagram Protocol (UDP) TCP and UDP port numbers 11.2 The Application Layer Introduction to the TCP/IP application layer DNS FTP HTTP SMTP SNMP Telnet

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 36 Application Layer eg. Dialog Control is Session Layer in OSI Application Layer in TCP/IP

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Introduction to the TCP/IP application layer Domain Name System (DNS) File Transfer Protocol (FTP) Hypertext Transfer Protocol (HTTP) Simple Mail Transfer Protocol (SMTP) Simple Network Management Protocol (SNMP) Telnet

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide DNS eg.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide DNS eg. Non-Profit organizations

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide DNS.us USA.ca Canada.au Australia.cl Chile.de Germany.hk Hong Kong

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide FTP and TFTP Both TFTP and FTP are used to transfer files between systems. TFTP is limited to Read, Write and Mail. In Semester 2 we will use TFTP to load and retrieve ISO images from a router. FTP uses TCP thence is connection oriented. TFTP uses UDP thence is NOT connection oriented.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide HTTP Eg. …the TCP protocol is http, the domain name is slctech.org, the machine is uno, and the folder is ~clark. DNS is used to translate a web address into an IP address. HTTP (not shown port 80) uses TCP thence is connection oriented. DNS can use either TCP or UDP.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 43 SMTP offers very little security no authentication SMTP servers communicate with each other using SMTP. Clients collect their mail using POP3 or IMAP4. SMTP uses TCP

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide SNMP Network Management System is the central point for SNMP. It uses the majority of memory resources. Managed devices: Eg. Routers, switches, hosts etc. Agents report back to the NMS the status of the items in their MIBs

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 45 Network management system (NMS) NMS executes applications that monitor and control managed devices. The bulk of the processing and memory resources required for network management are provided by NMS. One or more NMSs must exist on any managed network. Managed devices Managed devices are network nodes that contain an SNMP agent and that reside on a managed network. Managed devices collect and store management information and make this information available to NMSs using SNMP. Managed devices, sometimes called network elements, can be routers, access servers, switches, and bridges, hubs, computer hosts, or printers. Agents Agents are network-management software modules that reside in managed devices. An agent has local knowledge of management information and translates that information into a form compatible with SNMP.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Telnet Telnet uses TCP thence is connection oriented.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 47

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 48 OVERVIEW 11.1 TCP/IP Transport Layer Introduction to transport layer Flow control Session establishment, maintenance, and termination overview Three-way handshake Windowing Acknowledgment Transmission Control Protocol (TCP) User Datagram Protocol (UDP) TCP and UDP port numbers 11.2 The Application Layer Introduction to the TCP/IP application layer DNS FTP HTTP SMTP SNMP Telnet

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod11 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 49 FIN