ITEC 370 George Vaughan Franklin University Protocols ITEC 370 George Vaughan Franklin University

Sources for Slides Material in these slides comes primarily from course text, Guide to Networking Essentials,Tomsho, Tittel, Johnson (2007). Other sources are cited in line and listed in reference section.

TCP/IP and OSI Models

Function of Protocols Protocol = Rules for communication Protocols exist for each layer of OSI model. Some protocols span more than one layer. Higher layer protocols are more abstract. When protocols work together to cover multiple OSI layers, they are referred to collectively as a protocol stack (or suite).

Connectionless and Connection-Oriented Protocols No guarantee of delivery Low overhead, faster Connections don’t have to be setup or torn down Rely on upper layers to provide reliable communications Connection Oriented Reliable but slower Receiver sends acknowledgement to indicate successful transfer Packets are resent in event of error Upper layers don’t have to worry about reliable transmission

Routable and Non-routable Protocols Operate at Network layer Support internetworks (MAN, WAN) Example: TCP/IP Non-Routable Does not operate at Network layer Useful for small LANs Example: NetBIOS Extended User Interface (NetBEUI)

TCP/IP and OSI Models

TCP/IP Network Layer Protocols Internet Protocol version 4 (IPv4 or IP) Source and Destination logical addressing, routing Connectionless Fast but not reliable Internet Control Message Protocol (ICMP) Used to send error and control messages Used by ‘Ping’ utility Address Resolution Protocol (ARP) Used to resolve logical (IP) address to physical (MAC) address Can only be used for two systems in same network.

Example of TCP/IP Network Layer Protocols Computer A needs to send a message to Computer B Before computer A can send message, it needs the following addresses for computer B: IP (logical address) MAC (physical address) Computer A sends out ARP broadcast message to all devices. Computer B recognizes IP address in ARP and sends back MAC address to computer A Computer A now has 2 addresses necessary for send message to computer B.

TCP/IP Transport Layer Protocols Transmission Control Protocol (TCP) Accepts messages of any length from upper layers Connection-Oriented Uses 3-way handshake to establish connection A sends ‘Synchronize’ (SYN) message to B B sends ‘Synchronize Acknowledgement’ (SYN-ACK) message back to A A sends a ‘Forward Acknowledgment’ (ACK) to B Connection between A and B is now established. TCP is responsible for fragmenting application into segments TCP is responsible for reassembling the application data from segments. TCP uses Acknowledgment messages to: Ensure that data is properly received. Manage flow control

TCP/IP Transport Layer Protocols (Cont.) User Datagram Protocol (UDP) Connectionless Faster, but less reliable than TCP UDP itself does not segment application data UDP does not use acknowledgements UDP is used by some higher layer protocols such as NFS and DNS.

TCP/IP Application Layer Protocols Domain Name System (DNS) Name-to-Address resolution system einstein.franklin.edu  65.24.7.3 (try ‘nslookup einstein.franklin.edu’ Hypertext Transport Protocol Web-pages, browsers, servers File Transfer Protocol (FTP) Telnet Simple Mail Transport Protocol (SMTP)

TCP/IP Application Layer Protocols Tomsho, Tittel, Johnson (2007) DHCP Detailed configuration of devices, keeping track of assigned addresses and to which machine they were assigned, etc., is difficult in large networks DHCP was developed to make this process easier DHCP server must be configured with a block of available IP addresses and their subnet masks Clients must be configured to use DHCP Broadcast request message is sent on boot Client leases the address the server assigns to it If no answer is received, in an APIPA-enabled OS, the computer assigns itself an address (169.254.x.x)

IP Addressing IP addressing is responsible for routing in TCP/IP environment. Example: 192.203.187.0 IP address is 32 bits long (4 bytes) Special IP addresses: 255.255.255.255 = Broadcast 127.xxx.xxx.xxx = Localhost IP address is divided into 2 parts Network Identification Host Identification

Scope of Transmission Hosts in same network (same Network ID) can be connected with switches/hubs Router is required to transmit to hosts outside of network (different Network ID). Broadcast messages can only be transmitted to hosts within same network (broadcast domain).

Types of IP Addressing The demarcation point in the 32 bit address between network ID and host ID depends on addressing scheme: Class Based Addressing generally uses a byte boundary as the dividing point Classless Based Addressing uses a bit boundary.

Class Based IP Addressing (Cisco – IP Addressing, n.d.). Used less frequently now, CIDR preferred

Internet Protocol Version 6 Limitations with IPv4 32 bit address space is limited No Quality of Service (QoS) support IPv6 Features: Incorporates IPSec 128 bit address Auto-configuration No IP address to assign No subnet mask to determine 2 methods of auto-configuration Stateless Host creates its own IP address based on router information and MAC address Simplest and most common Stateful Relies on DHCP server

IPv6 Address Scheme Hexidecimal grouped in 16 bit sections: 2001:1b20:302:442a:110:2fea:ac4:2b Leading zeroes are eliminated 2 or more 16 bit fields of all zeros can be ignored: 2001:260:0:0:0:2ed3:340:ab (long form) 2001:260::2ed3:340:ab (short form) IPv6 has 3 parts:

Other Protocol Suites Tomsho, Tittel, Johnson (2007) Other protocol suites are sometimes used on older networks, where the need to change to TCP/IP is not warranted, or in environments suited to the suite’s features NetBIOS/NetBEUI Used primarily on older Windows networks IPX/SPX Designed for use on NetWare networks AppleTalk Used almost exclusively on Macintosh networks

References Tomsho, Tittel, Johnson (2007). Guide to Networking Essentials. Boston: Thompson Course Technology. Odom, Knott (2006). Networking Basics: CCNA 1 Companion Guide. Indianapolis: Cisco Press Wikipedia (n.d.). OSI Model. Retrieved 09/12/2006 from http://en.wikipedia.org/wiki/OSI_Model Cisco – IP Addressing (n.d.). IP Addressing. Retrieved 09/27/2006 from http://cco.cisco.com/warp/public/701/3.html#figone IANA (n.d.) Abuse Issues and IP Addresses . Retrieved 11/11/06 from http://www.iana.org/faqs/abuse-faq.htm