Design an IP address scheme according to organisational requirements

What is a protocol? 2 Why protocols are used in networking 2 Examples of different protocols 3

The ISO/OSI reference model 4 The seven layers explained 6

Introduction to TCP/IP 9 How TCP/IP works 9

What is an IP address? 12 Components of an IP address 12 Classes of IP addresses 13

Subnet masks 15

Binary and decimal conversion 17

Subnetting 19

Routing 20 Routing tables 21

IP Version 6 (IPv6) 23

Summary 24 Check your progress 24

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What is a protocol?

For communication to occur there has to be some form of common language and some guidelines that are used to manage the communication process. With respect to computers and information technology, a protocol is a standard framework, which dictates how two or more computers communicate with each other and share information over a particular data link.

Why protocols are used in networking Protocols define the rules or standards for communication between network devices. A printer cannot interpret signals sent by other devices, such as a workstation or file server, unless there is a common protocol. Protocols enable data to be sent between two devices in sequence and without errors.

Examples of protocols used on networks include:  Transmission Control Protocol/Internet Protocol (TCP/IP)  Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX)  NetBIOS (Network Basic Input Output System)  NetBIOS Enhanced User Interface (NetBEUI)  AppleTalk.

Protocols need to be installed and configured on both devices before communication can take place between those devices, eg a workstation and a file server.

With respect to networking, the term ‘protocol’ actually refers to a group or suite of individual protocols that work together. Different tasks are assigned to protocols within a suite, such as data translation, data handling, addressing or error checking.

There are many factors that determine which protocol (protocol suite) you may use on a network. Factors include:  the error rate on the data link  whether Internet access is required (this is important as some protocols are not routable)

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 the network operating system being used  how much network security will be required  the speed requirements of the network.

Examples of different protocols Below you will find some examples of the different protocols with a brief explanation for each.

Internet Packet Exchange (IPX) and Sequenced Packet Exchange (SPX)

This is a suite of protocols, made up of many protocols, not just IPX and SPX. It was originally developed by Xerox and adopted by Novell in the 1980s.

Novell’s NetWare clients and servers use this suite of protocols. It is routable, meaning that it can cross many LAN segments. IPX works at the network layer and is connectionless, that is the protocol does not guarantee delivery of data.

The IPX protocol is responsible for addressing. SPX is responsible for ensuring that data is received in sequence and error free.

NetBIOS and NetBEUI

The Network Basic Input Output System (NetBIOS) was originally developed by IBM and later adopted by Microsoft to be used in small local area networks.

NetBEUI (NetBIOS Enhanced User Interface) is a fast and efficient protocol that is still used on small networks.

However, this protocol is not routable, that is it cannot span the Internet. However, many systems still require the presence of the NetBIOS protocol services to function correctly. The NetBIOS protocol services can be implemented on routed networks by ‘riding’ on TCP/IP through the routers, that is TCP/IP encapsulates NetBIOS.

AppleTalk

This protocol was developed to interconnect Apple Macintosh computers. This is a routable protocol.

To find out more information on these and other protocols, you can follow the links in the Research section of this Learning Pack.

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The ISO/OSI reference model

In the early 1980s the International Standards Organisation (ISO) developed a model or theoretical representation of what happens between two computers on a network. The model known as the Open Systems Interconnection (OSI) is the blueprint that has helped networking specialists to understand and develop computer-to-computer communications.

The goal of establishing the reference model was to allow different computers from different manufacturers, running different operating systems to communicate with each other, so long as each system conformed to the OSI reference model.

The model has seven layers: 1 application 2 presentation 3 session 4 transport 4 network 6 data link 7 physical.

Each layer of the OSI model has its own function and interacts with the layers directly above and below it.

Figure 1 below shows information going down the seven layers from one device across intermediate devices, and then up through the seven layers on the destination device. These devices can be any type of network equipment such as networked computers, printers and internetworking devices such as routers and switches.

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Sending device Receiving device

Application Application \

Presentation Presentation

Session Session

Transport Transport

Network Network Network Network

Data Link Data Link Data Link Data Link

Physical Physical Physical Physical

Figure 1: The ISO/OSI reference model showing communication between two devices

Here is a simple mnemonic to help you remember the order of the seven layers of the OSI model:

All Application 7

People Presentation 6

Seem Session 5

To Transport 4

Need Network 3

Data Data Link 2

Processing Physical 1

Figure 2: Remembering the seven layers of the OSI model

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The seven layers explained

Physical layer

The physical layer is the bottom layer of the OSI model. Its function is to simply:  Transmit bits over the network media. This layer contains the physical networking media such as cabling, connectors and repeaters.  Specify the mechanical, electrical and functional means of establishing and maintaining the physical connections. That is, how the electrical signals are amplified and transmitted over the wire. The layer sets the data transmission rate and monitors data error rates, although it does not provide for error correction — which is done at another level.

The physical layer thus activates and deactivates the physical connection. A severed wire or a NIC (network interface card) not seated deeply enough are some of the network problems that can be experienced at the physical layer.

Data link layer

The second layer of the OSI model is the data link layer. Its primary purpose is to provide a reliable method of transmitting data across the physical media.

The data link layer divides data it receives from the network layer into frames that can then be transmitted by the physical layer. A header and trailer are added to the frames. These allow the destination device to see when a frame begins or ends on the physical media.

The frames are then transmitted sequentially, and the sender’s data link layer waits for an acknowledgement from the receiver that data was received correctly. If the sender does not get this acknowledgment, its data link layer gives instructions to retransmit the information. The data link layer is divided into two sub-layers — the Media Access Control (MAC) sub-layer and the Logical Link Control (LLC) sub-layer.

Media Access Control (MAC)

The MAC sub-layer is responsible for the physical addressing of devices on the network and how these devices gain access to the network media. The physical addressing at the data link layer is called a physical address, because this address is hard-coded into the network interface card by the manufacturer. The address is also known as the MAC layer address. Each device has a unique address that provides the necessary information to direct data to and from devices on the local network.

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Logical Link Control (LLC)

The LLC sub-layer is responsible for flow control and error correction at this layer and provides two service types:

The unacknowledged connectionless service is unreliable as data is transferred with no error checking. The Connection-oriented service — is slower than the connectionless service, as data is checked for errors using Cyclic Redundancy Checks (CRC). CRC is one method of detecting errors in transmitted data. Before the data is sent, a CRC number is calculated by running the data through an algorithm, which produces a unique number. The data is run through the same algorithm again at the receiving end. If the numbers are the same, the data was then sent error free. The number generated by the algorithm is called a checksum.

Flow control is important not only at the LLC sub-layer but also at all layers of the OSI model. It’s important to make sure that the transmitter doesn’t flood the receiver with data resulting in buffer overflow and lost data.

Network layer

The network layer is responsible for routing information from the sender to the receiver. It accepts messages from the transport layer, converts them into packets and ensures that the packets are directed towards their destination. The network layer determines the best path that the packets should take from point A on one network to point B on another network. It does this by checking to see if the destination device is on another network.

Transport layer

The prime responsibility of the transport layer is to ensure that the data transferred from point A to point B is reliable, in the correct sequence and without errors. The transport layer accepts the data from the session layer and splits it up, if required. It then forwards the data to the network layer and checks that the data has arrived successfully on the destination device — this is a connection-oriented service. If an acknowledgement is not received within a specified period of time, the data is re-sent by the sending device. Acknowledgements are used to control the flow of data.

Session layer

The session layer allows users to establish a connection — a session. Once the session has been established the session layer maintains and co- ordinates the communication. For the user to establish a session, they need to provide a remote address. The address can be a domain name such as www.tafensw.edu.au or the NetBIOS name of the computer, for example, Serv007.

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Presentation layer

The presentation layer is responsible for translating data into a format that can be understood by each computer. The important task at this layer is code translation. For example an IBM mainframe may transmit a message in EBCDIC format to a PC that uses ASCII format. Despite the coding differences, data can still be displayed on the receiving device, the PC.

ASCII, EBCDIC, BMP, WAV and UNICODE are examples of presentation layer code translations. (Refer to Terms for definitions of these.) The presentation layer is also responsible for data encryption and foreign language translations.

Application layer

The application layer is the seventh and last layer of the model. It is the only level at which the user has direct contact with the model. This layer starts a network application, such as transferring files, or provides access to the Internet. Do not confuse the application layer with software such as word processing or spreadsheet applications. The application layer makes network services such as file, print, message, application and database services available to a computer’s local operating system.

The application layer determines the quality of service at the lower layers. If a problem occurs at a lower layer, the application layer provides a means of notifying the user that there is a problem. The notification is usually in the form of an error message, for example, host not reachable, printing device not connected, etc.

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Introduction to TCP/IP

TCP/IP stands for Transmission Control Protocol/Internet Protocol. It is the basic protocol of the Internet. It is a scalable protocol, which can be used on a small private network, such as your home network or a company’s private Intranet, or it can be used on a large company network like the one at Forth Management Associates.

TCP/IP has become the de-facto standard for Internet communications. There are many reasons for this:  TCP/IP has been accepted as the industry standard protocol.  It is a routable protocol suite.  Almost all computer operating systems support the TCP/IP protocol.  It allows computers using different operating systems to connect to each other (such as a UNIX computer to a Windows XP computer).  It is an open standard — no company has control over the protocol. Anyone is allowed to use it and develop applications based on it.  It is a well-designed protocol.

How TCP/IP works TCP/IP is not just two protocols, but a suite of which includes TCP, IP, UDP, ARP, ICMP and other sub-protocols. The suite of protocols can be divided into four layers that roughly correspond to the seven layers of the OSI model, as shown in Figure 3.

Application Presentation Application Session Transport Transport Network Internet Data link Physical Network interface

Figure 3: Approximate correspondence of four layers of TCP/IP to OSI model

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TCP/IP is a multiple-layer protocol, which provides an application service as well as a network service, as can be seen in Figure 4 below.

HTTP FTP

Application Sockets

Transportation TCP UDP

ICMP Internet IP ARP

Network Interface Network Device

Figure 4: TCP/IP application and network services

TCP and IP are the core protocols in the suite, and along with UDP, ICMP, ARP and other sub-protocols provide a network service.

Internet Protocol (IP)

The Internet Protocol belongs to the Internet Layer of the TCP/IP model. It provides information on how and where data is to be delivered — a key feature of Internetworking. For this reason the TCP/IP protocol is able to span more than one LAN segment, usually through a router.

The IP portion of the data frame is called an IP datagram. The datagram contains information for routers so that data can be transferred between individual networks.

IP is a connectionless protocol. This means that it does not guarantee delivery of data. Higher-level protocols use IP information to ensure that data packets are delivered to the right address.

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Transmission Control Protocol (TCP)

TCP belongs to the transport layer of the TCP/IP suite. It provides a reliable data delivery service known as a connection-oriented service — this means that a connection must be established between two devices before TCP will transmit data. TCP provides checksum, flow control and sequencing information, which ensures that the data is reassembled in the correct order.

User Datagram Protocol (UDP)

UDP belongs to the transport layer of the TCP/IP suite. It is a connectionless service — it does not guarantee that the packets will be received in the correct order and provides no error checking or sequencing. UDP is used when data needs to be transferred quickly, for example, in live audio or video transmissions over the Internet.

Internet Control Message Protocol (ICMP)

ICMP belongs to the Internet layer of the TCP/IP suite. It is responsible for notifying the sending device of a problem with transmission, for example, when packets are not delivered. It provides a message to the sending device, such as ‘Host unreachable’ (how many times have you seen this?). ICMP is used by diagnostic utilities, such as PING.

Address Resolution Protocol (ARP)

ARP also belongs to the Internet layer of the TCP/IP suite. ARP is used to determine an unknown MAC address of a remote device to which a packet is to be sent. The header of an IP packet contains the MAC and IP address of the source and the MAC and IP address of the destination. The resulting IP/MAC address information is held on the sending machine in an ARP table.

Application service

The TCP/IP suite also provides an application service with the protocols:  Hypertext Transfer Protocol (HTTP)  Telnet  Hypertext Transfer Protocol security  File Transfer Protocol (HTTPs) (FTP)  Simple Network Management Protocol  Simple Mail Transfer (SNMP) Protocol (SMTP)

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What is an IP address?

Every device on a network (printer, workstation, server, etc) requires a unique identifier. If all the devices are on the same local area network, then only a physical (MAC) address is required. This is the same as saying that all we need to uniquely identify any house in the same street is to have its house number. However, if the destination device is on a different network then a logical address is also required. This is the same as saying that all we need to uniquely identify any house in NSW is to have its house number, its street name and its town name. The IP address is the logical address that allows data to be sent to devices on different networks. Logical addresses must conform to the standards and rules of the protocol, thus IP addresses are assigned according to specific rules and standards and are configured by the network administrator.

Components of an IP address An IP address is a 32-bit binary number, for example:

11001011 00111100 00000001 00000010

For ease of use, this is normally represented in a dotted decimal format, eg:

203.60.1.2.

Each 8-bit octet is represented by a whole number between 0 and 255. Each IP address consists of two fields:  a net ID field that is the logical network address of the device  a host ID field, which is the logical device’s address that uniquely identifies each device on the network.

Together, the net ID and the host ID provide each device on a network with a unique IP address.

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Classes of IP addresses There are five classes of IP addresses, however only three classes are commonly used. Table 1 below shows the commonly used TCP/IP classes.

Table 1: Commonly used TCP/IP classes if IP addresses

Class First Octet Number of Networks Number of addresses per network

A 1 – 126 126 16, 777, 214 B 128 – 191 16, 384 65, 534 C 192 – 223 2, 097, 154 254 Note: Class D and E are not available for standard network addressing.

You can identify the class of an IP address by examining the first octet.

All nodes in a Class A network share the first octet of their IP address. Class A addresses range between 1 and 126. An example of a Class A address is 125.10.15.1. The net ID portion of the IP address is 125 and the host ID portion of the IP address is 10.15.1.

All nodes in a Class B network share the first two octets of their IP address. Class B addresses range between 128 and 191. An example of a Class B address is 158.10.15.1. The net ID portion of the IP address is 158.10 and the host ID portion of the IP address is 15.1.

All nodes in a Class C network share the first three octets of their IP address. Class C addresses range between 192 and 223. An example of a Class C address is 200.10.15.1. The net ID portion of the IP address is 200.10.15 and the host ID portion of the IP address is 1.

Class A networks have a Class B networks have a binary address starting with binary address starting with 00 000000 as the first octet: 10 000000 as the first octet;

Binary Decimal Binary Decimal 00 000000 0 10 000000 128

00 000001 1 10 000001 129

00 000010 2 10 000010 130 ~ ~ ~ ~ ~ ~ ~ ~ 00 111110 126 10 111110 190 00 111111 127 10 111111 191 Class C networks have a As there are only 126 Class A

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binary address starting with networks available on the Internet, 11 000000 as the first octet. most Class A networks have been reserved by large corporations or Binary Decimal governments. Some IP addresses 11 000000 192 have been reserved for network functions such as broadcasts and 11 000001 193 cannot be assigned to devices. 11 000010 194 As you know, all rules have ~ ~ ~ ~ exceptions and this also applies to IP 11111110 222 addressing. The following section 11 111111 223 discusses special IP addresses.

Special IP addresses

Here are some of the restrictions you should keep in mind — you will need to remember them!

First octet value of 127

Any address with a first octet value of 127 is a loopback address, which is used for diagnostics and testing. A message sent to an IP address with the first octet of 127 is returned to the sender. The IP address 127.0.0.1 is known as the loopback address and is used for this purpose. Therefore, 127 cannot be used as a net ID, although it is technically a Class A address.

255 in an octet

255 in an octet is designated as a broadcast. A message sent to 255.255.255.255 is broadcast to every host on the local network. For example, a message sent to 158.8.255.255 is broadcasted to every host on network 158.8.

Addresses for private Local Area Networks (LANs)

There are three groups of IP addresses to choose from if you wish to create a private LAN (for example, an Intranet for a company, for use at home and not on the Internet): 10.0.0.0 to 10.255.255.255 172.16.0.0 to 172.31.255.255 192.168.0.0 to 192.168.255.255 The first octet cannot have a value above 223. Those addresses are reserved for multicast and experimental purposes.

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Subnet masks

Besides an IP address, every computer on a network must be configured with a subnet mask. The subnet mask allows routing devices to separate the IP address into its net ID and host ID portions.

Network management is made easier if a network is broken into smaller segments. However, a business is allocated a single IP address that covers its net ID address and a range of host ID addresses. By using some of the host ID bits as segment addresses, segmentation can occur and network management made easier.

The subnet mask identifies whether a computer is on the same local network or on another network that needs to be contacted through a router. Subnet masks make it easier and faster to identify the net ID portion of the IP address. It allows TCP/IP to determine if network traffic destined for a given IP address should be transmitted on the local network, or whether it should be routed to a remote network.

A subnet mask should be the same for all computers and other network devices on the same network segment.

The subnet mask is a 32-bit binary number, broken into four 8-bit octets.

A common subnet mask is 255.255.255.0. This particular subnet mask specifies that TCP/IP will use the first three octets of an IP address as the network id and the last octet as the host ID.

The subnet mask is dependent on the class of IP addresses in use on the network. The following subnet masks are used for the following Classes of IP addresses: Class A: 255.0.0.0 Class B: 255.255.0.0 Class C 255.255.255.0 Note: If subnet masks are incorrectly configured, routing errors will occur.

How do you obtain an IP address?

IP addresses can be requested from the Internet Corporation for Assigned Names and Numbers (ICANN) — a non-profit organisation set up to maintain and assign IP addresses. Here in Australia, various agents such as

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Internet Service Providers (ISPs) can apply to the ICANN for IP addresses on your behalf or lease some of their ‘reserved’ IP addresses to you.

An organisation does not normally obtain an IP address for each staff member. The range of IP addresses a company will lease will depend on the number of servers in the organisation that will require Internet access such as a web or remote access servers. Most organisations usually lease a small number of IP addresses. Internally, organisations use addresses from the private address range to allocate to staff members.

Real IP addresses are allocated to the web and proxy servers, as well as other devices such as routers that communicate with other devices on the Internet. These devices have a legitimate IP address, however, the workstations and other devices on the company’s network use addresses from the private ranges.

A NAT (Network Address Translation) server can be used to hide the IP addresses assigned to devices on the network from any public network, such as the Internet. When a node’s transmission reaches the IP gateway, the gateway assigns the client’s transmission with a valid IP address. In this way, the company’s internal IP addresses are protected and network administrators have more flexibility in assigning addresses.

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Binary and decimal conversion

Computers store information in binary form, that is, in 0s or 1s. Binary uses the Base2 counting system. To create subnets and work out the decimal equivalents of the binary bit pattens, it’s useful to learn how to convert decimal numbers into binary and vice versa (without a calculator!)

To convert a number into binary or decimal it is best to use this table.

0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 First row: the 0/1 refers to the value of a bit, that is, zero or one

27 26 25 24 23 22 21 20 Second row: represents the binary system; increases in value to the power of 2 (as opposed to the decimal system, which increases to the power of 10)

128 64 32 16 8 4 2 1 Third row: the decimal values of the second row.

Rules for converting

Using the table above, you will need to apply the following rules:  multiply the bit by its positional decimal equivalent  add the value of the decimal equivalents of all the bits to determine the total decimal value of the binary number.

For example

1 1 0 0 1 0 1 1 X X X X X X X X 128 64 32 16 8 4 2 1 128 64 0 0 8 0 2 1 Decimal value = 203 0 0 1 1 1 1 0 0 Decimal value = 60 0 0 0 0 0 0 0 1 Decimal value = 1 0 0 0 0 0 0 1 0 Decimal value = 2

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So, the IP address 203.60.1.2 203 60 1 2 has the corresponding binary 11001011 00111100 00000001 00000010 values:

In binary within a computer, this would be stored as: 11001011001111000000000100000010

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Subnetting

A large network can be divided into smaller or multiple networks by subdividing a single class of IP addresses. Network Administrators can use one class of addresses for several network segments. A subnetted address includes the network, subnet, and host information.

Say your organisation is assigned a Class B network ID of 152.77.0.0. The standard subnet mask would be 255.255.0.0. The number of valid IP addresses would range from 152.77.0.1 to 152.77.255.254. To divide this range of IP addresses into 6 networks you would need to apply the formula:

2n –2 where n = to the number of bits.

In the above example, the standard subnet mask is 255.255.0.0.which when converted to binary is: 11111111.11111111.00000000.00000000.

By borrowing 3 bits, the new subnet mask becomes: 1111111.11111111.11100000.00000000 — which converts to the decimal format: 255.255.224.0. In this example, a 3-bit subnet mask is used. There are 6 (23 –2) subnets available with this subnet mask. Remember that subnets with all 0s and all 1s are not allowed — these are reserved for specifying the local network. The valid range of IP addresses for the five subnets is shown in Table 2.

Table 2: Valid range of IP addresses for five subnets

Subnet bits Network number Node Addresses 001 152.77.32.0 152.77.32.1 to 152.77.63.254 010 152.77.64.0 152.77.64.1 to 152.77.95.254 011 152.77.96.0 152.77.96.1 to 152.77.127.254 100 152.77.128.0 152.77.128.1 to 152.77.159.254 101 152.77.160.0 152.77.160.1 to 152.77.192.254 110 152.77.192.0 152.77.192.1 to 152.77.223.254 The combination of an address’s network and subnet information becomes an extended network prefix. The extended network prefix, enables a device to determine the subnet to which the address belongs. Subnet masks allow you to sub-allocate network addresses. Subnetting, is a complex procedure, which you can learn more about with further reading and after completing this unit.

Websites providing further exercises and examples of subnetting can be found in the Research section of this Learning Pack.

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Routing

A router is a device that determines the next network point to which a packet should be forwarded toward its destination. The router is connected to at least two networks and decides which way to send each information packet based on its current understanding of the state of the networks it is connected to.

Routers create and maintain a table of the available routes and their conditions and use this information along with the distance to determine the best route for a given packet. Typically, a packet may travel through a number of network points with routers, before arriving at its destination. Routing is a function associated with the network layer (layer 3) in the standard model of network programming, the OSI model.

In most cases, a router is located at any gateway (where one network meets another). In Figure 5 below two networks are connected by a router with IP address 192.168.1.1 and 203.60.1.4, subnet mask 255.255.255.0. The router acts as a gateway and will handle all the incoming and outgoing network traffic, and as can be seen in Figure 5, the router will handle the traffic between these two networks, which will also apply to the way the router connects to the Internet.

203.60.1.1 203.60.1.2 203.60.1.3

203.60.1.4

192.168.1.1

192.168.1.2 192.168.1.3 192.168.1.4

Figure 5: Two networks connected by a router

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Routing tables TCP/IP hosts use a routing table to maintain knowledge about other IP networks and IP hosts. As you now know, using an IP address and a subnet mask identifies networks and hosts.

In addition, routing tables are important because they give needed information to each local host regarding how to communicate with remote networks and hosts.

For each computer on an IP network, you can maintain a routing table with an entry for every other computer or network that communicates with the local computer. In general, this is not practical, and a default gateway (IP router) is used instead.

When a computer prepares to send an IP datagram, it inserts its own source IP address and the destination IP address of the recipient into the IP header. The computer then examines the destination IP address, compares it to a locally maintained IP routing table, and takes appropriate action based on what it finds. The computer does one of three things, it:  passes the datagram up to a protocol layer above IP on the local host.  forwards the datagram through one of its attached network interfaces.  discards the datagram.

IP searches the routing table for the route that is the closest match to the destination IP address. The most specific to the least specific route is searched for in the following order:  a route that matches the destination IP address (host route)  a route that matches the network ID of the destination IP address (network route)  the default route.

Figure 6 shows a default routing table that can be accessed through the command prompt ‘route print’. It shows the current IP address and subnet mask of the local interface card and where it should forward its network traffic, in this case 0.0.0.0 of network destination will have to forward to 192.168.0.1. This means that all traffic will be handled by the 192.168.0.1 (which is default gateway/router), and the router will decide where to forward the traffic.

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Figure 6: A default routing table

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IP Version 6 (IPv6)

For over 20 years now, the IT industry has been using IPv4. As you have read, with IPv4, IP addresses are unique — each computer or device on the network is allocated an IP address and a subnet mask. By the late 1980s it was realised that the world would run out of IP addresses and work began on the IP Next Generation (IPng) project: IPv6.

IPv4 uses a 32-bit address space, which permits an absolute maximum of 232 (4,294,967,296) hosts to connect to the Internet at any given time. Today, not only do businesses, government departments and schools have Internet access, but also most homes have at least one computer that accesses the Internet.

IPv6 addresses are four times as long as IPv4 addresses and at 128 bits provide an absolute maximum of 2128 individual hosts. This is roughly 340 billion billion billion different hosts! (Would you like to check this calculation!)

IPv6 is now included as part of IP support in many products, from 3Com and Hitachi, and including the major computer operating systems. There are no plans (at this stage anyway) for a cutover date when IPv6 would be turned on and IPv4 turned off.

One of the strategies chosen for the upgrade is to deploy the IPv6 protocol stack in parallel with IPv4. This means that hosts that upgrade to IPv6 will continue to exist as IPv4 hosts at the same time.

An experimental IPv6 backbone or 6bone, has been set up to handle IPv6 Internet traffic in parallel with the regular Internet. These devices will continue to have 32-bit IPv4 addresses but will add 128 bit IPv6 addresses.

We suggest you do some follow up reading on IPv6 at: http://www.ipv6.org/

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Summary

In this topic the term protocol and its definition were introduced with respect to information technology.

A protocol is a standard or rule that dictates how two or more computers communicate with each other and share information. There are many network protocols in use today, such as IPX/SPX, AppleTalk, NetBEUI and TCP/IP. However, TCP/IP has become the de-facto standard of the Internet. It is the protocol of choice for most networks, whether they are connected to the Internet or not. It enables different computers running different operating systems on different networks to communicate with each other and share information.

The TCP/IP protocol is a suite of protocols or protocol stack, made up of core protocols such as TCP, IP and sub-protocols such as UDP, ARP, ICMP to name a few.

Every device on a network is logically configured with a unique IP address and subnet mask which determines the network the device is located on. Each IP address and subnet mask is a 32-bit binary number normally represented in dotted decimal format.

IP addressing and subnet masks provide useful information to network devices such as servers, other workstations and routers. This information enables data to be routed from one network to another.

Transition strategies have been in place since 1999 to migrate from IPv4 to IPv6 in the near future.

Check your progress Now you should try and do the Practice activities in this topic. If you’ve already tried them, have another go and see if you can improve your responses.

When you feel ready, try the ‘Check your understanding’ activity in the Preview section of this topic. This will help you decide if you’re ready for assessment.

24 Readings: Design an IP address scheme according to organisational requirements 2005