McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 TCP/IP

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure 24-1 An Internet According to TCP/IP

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure 24-2 TCP/IP and the OSI Model

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Comparison between OSI and TCP/IP

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure 24-3 IP Packet

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure 24-4 Internet Address

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure 24-5 Internet Classes

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure 24-6 IP Addresses in Decimal Notation

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure 24-7 Class Ranges of Internet Addresses

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure 24-8 Network and Host Addresses

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure 24-9 A Network with Two Levels of Hierarchy

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure A Network with Three Levels of Hierarchy

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure Addresses with and without Subnetting

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure Masking

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure Private and Reserved Addresses The following addresses are reserved for private use. They are typically non-routing. Network address Default mask is reserved for loopback and is used for internal testing on the local machine.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure Where Do I Get an IP Address? Three regional Internet registries assign Internet Protocol addresses – ARIN RIPE NCC APNIC

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure Where Do I Get an IP Address? Because IP addresses are in such short supply due to inefficient assignment of addresses, it’s nearly impossible anymore for anyone but an Internet Service Provider to get an address from one of these agencies. We now get our addresses from our Internet Service Providers.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure Classes and Classless Class A - supports 16 million hosts on each of 127 networks Class B - supports 65,000 hosts on each of 16,000 networks Class C - supports 254 hosts on each of 2 million networks

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure Classes and Classless Of the total address space: 50% is assigned to class A networks 25% is assigned to class B networks 12.5% is assigned to class C networks A very small fraction of class A addresses have been assigned to workstations.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure Classes and Classless Because of this inefficient assignment of addresses, longer addresses and the idea of classless addresses was developed.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure IPv4 vs IPv6 IPv6 was developed because of the shortage of IP addresses. IPv4- 32 bit addresses, about 4 billion IPv bit addresses, about 4 billion billion However, if these addresses are not assigned efficiently, even this may not be enough

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure IPv4 vs IPv6 Along with IPv6, a classless structure was proposed. Networks were defined on the bit level, rather than at a multibit level

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure CIDR CIDR stands for Classless InterDomain Routing. It is also sometimes called Supernetting. The idea is to subnet based at the bit. CIDR notation looks like this: Class A = /8 Class B = /16 Class C = /24)

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure CIDR The number after the “/” is the number of bits in the subnet mask Class A = /8 For example: , with subnet mask of , or

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure CIDR The number after the “/” is the number of bits in the subnet mask Class B = / , subnet mask , Class C = /24) , subnet mask ,

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure CIDR What happens if you want a network larger than 254 nodes? Say, about 1000? You can combine 4 class C addresses, , and change the subnet mask /22, subnet mask ,

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure CIDR The network address is calculated by ANDing the associated class C IP addresses ( ) ( ) ( ) ( ) ( )

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Local Login

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Remote Login

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Telnet Telnet is a terminal emulation program for TCP/IP networks such as the Internet. The Telnet program runs on your computer and connects your PC to a server on the network. You can then enter commands through the Telnet program and they will be executed as if you were entering them directly on the server console. This enables you to control the server and communicate with other servers on the network. To start a Telnet session, you must log in to a server by entering a valid username and password. Telnet is a common way to remotely control Web servers.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 FTP

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 FTP File Transfer Protocol, or FTP, is a protocol used to upload files from a workstation to a FTP server or download files from a FTP server to a workstation. It is the way that files get transferred from one device to another in order for the files to be available on the Internet. When ftp appears in a URL it means that the user is connecting to a file server and not a Web server and that some form of file transfer is going to take place. Most FTP servers require the user to log on to the server in order to transfer files.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 HTTP In contrast, Hyper Text Transfer Protocol, or HTTP, is a protocol used to transfer files from a Web server onto a browser in order to view a Web page. Unlike FTP, where entire files are transferred from one device to another and copied into memory and then disk, HTTP only transfers the contents of a web page into a browser for viewing. FTP is a two-way system as files are transferred back and forth between server and workstation. HTTP is a one-way system as files are transported only from the server onto the workstation's browser. When http appears in a URL it means that the user is connecting to a Web server and not a file server.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 SNMP Concept

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 SNMP Messages

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure ARP

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 TFTP Abbreviation of Trivial File Transfer Protocol, a simple form of the File Transfer Protocol (FTP). TFTP uses the User Datagram Protocol (UDP)and provides no security features. It is often used by servers to boot diskless workstations, X-terminals, and routers.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 NFS Abbreviation of Network File System, a client/server application designed by Sun Microsystems that allows all network users to access shared files stored on computers of different types. NFS provides access to shared files through an interface called the Virtual File System (VFS) that runs on top of TCP/IP. Users can manipulate shared files as if they were stored locally on the user's own hard disk. Originally called Yellow Pages.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 SMTP Short for Simple Mail Transfer Protocol, a protocol for sending messages between servers. Most systems that send mail over the Internet use SMTP to send messages from one server to another; the messages can then be retrieved with an client using either POP3 or IMAP. In addition, SMTP is generally used to send messages from a mail client to a mail server. This is why you need to specify both the POP3 or IMAP server and the SMTP server when you configure your application.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 DNS Short for Domain Name System. It translates domain names into IP addresses. Because domain names are alphabetic, they're easier to remember. A network however, is really based on IP addresses. Every time you use a domain name, therefore, a DNS service must translate the name into the corresponding IP address. For example, the domain name might translate to

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Bootp or Bootstrap Short for Bootstrap Protocol, an Internet protocol that enables a diskless device to discover its own IP address, the IP address of a BOOTP server on the network, and a file to be loaded into memory to boot the machine. This enables the workstation to boot without requiring a hard or floppy disk drive. The protocol is defined by RFC 951. It uses TFTP, and thus UDP

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 DHCP Short for Dynamic Host Configuration Protocol, a protocol for assigning dynamic IP addresses to devices on a network. With dynamic addressing, a device can have a different IP address every time it connects to the network. In some systems, the device's IP address can even change while it is still connected. DHCP also supports a mix of static and dynamic IP addresses. A DHCP server may also provide subnet mask, domain Name, default gateway and DNS server

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure UDP Datagram Format

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure TCP Segment Format

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Ports Ports are the addresses for a process in the TCP/UDP layer of the TCP/IP protocol stack. When a workstation makes a request across the network, it’s not enough that the reply comes back to the same workstation. It must also come back to the same process

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Ports For example, you may decide to start downloading a file using FTP (port 21). While doing so you also decide to look at web pages using HTTP (port 80). The replies will come back to the same machine, but will be dealt with by a different process.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Figure Port Addresses

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Ports hnet/portnumbers/portnumbers.asp allows you to enter a protocol and get the port associated with that protocol. hnet/portnumbers/portnumbers.asp numbers is the site of the organization, IANA, that assigns port numbers. It has a complete list of ports in ASCII formathttp:// numbers

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Ports Ports are broken up into three sections: –The Well Known Ports are those from 0 through –The Registered Ports are those from 1024 through –The Dynamic and/or Private Ports are those from through 65535

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Ports The Well Known Ports are assigned by the IANA and on most systems can only be used by system (or root) processes or by programs executed by privileged users.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Ports The Well Known Ports are assigned and controlled by IANA. Some UDP ports you may be familiar with include: –69TFTP –111RPC –161SNMP –162SNMP trap

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Ports Some well-known TCP ports you may be familiar with include: –20FTP data –21FTP control –23Telnet –53DNS –80HTTP

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Ports The Registered Ports are those from 1024 through The Registered Ports are listed by the IANA and on most systems can be used by ordinary user processes or programs executed by ordinary users.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Ports The Dynamic and/or Private Ports are those from through These can be used by any process or user at any time, without restriction.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Ports Ports are used in the TCP [RFC793] to name the ends of logical connections which carry long term conversations. For the purpose of providing services to unknown callers, a Service Contact Port is defined. This specifies the port used by the server, such as a NAT server, as its contact port.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Ports Ports are assigned at each end of the conversation by the software. Some protocols use the same port every time, while others choose a different port for each conversation. Although both ends must assign a port number, they don’t necessarily have to assign the same port number. Both UDP and TCP use ports.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Sockets A socket is a combination of the IP address from the packet and the port number from the TCP or UDP address field. Together they uniquely define both the client and process.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 IP Internet Protocol provides a way to get data from network to network. The IP packet contains the IP address. It provides for a variable length data field It specifies which protocol it will encapsulate (eg TCP, UDP, etc) It has provision to limit the life of the packet

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 IP It provides for fragmentation of packets as they go from network to network It can handle a maximum datagram size of 65,535 bytes, which can be broken down for other network types including FDDI (4,352), Ethernet (1500), and X.25 (576).

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 PING Ping is a protocol hacked together early on in the development of networking Its function is to check to see if a network device is up and running

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 PING Ping is popularly defined as standing for Packet INternet Groper, is the definition given by Dave Mills, author of NTP and claimed author of PING Mike Muus, (died Oct in a traffic accident), also claimed authorship. He said that the name had no such origin. He named it after the echolocation method used by submariners, which, in turn, was named after the sound the method made.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 PING Whoever originally wrote it, ICMP is a protocol in the TCP layer which uses two types of messages: Error-Reporting and Query Query uses one of four types of messages, including Echo Request and Reply. Ping combines the Echo Request and Reply function of ICMP with UDP in an IP packet to validate whether a node is functioning

McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 PING Ping Time is the time it takes for a packet to go from the source to destination and back again, including all delays from intermediate routers, processing delays, and network congestion delays. The ping protocol is not a single protocol. It uses a combination of protocols; ICMP and UDP