(i)NetBEUI
NetBEUI stands for NetBIOS Extended User Interface. It is an old Microsoft networking protocol used in small networks. This protocol provides services at the Transport and Network layer of the OSI model. It is not a routable protocol and cannot be used on large routed networks. It is easy to install and is the fastest of all protocols.
Computers using the NetBEUI protocol use NetBIOS naming conventions. NetBIOS computer names consist of a maximum of 15 characters, such a Server1 or Workstation1. NetBEUI uses the following three methods to resolve NetBIOS computer names to IP addresses:
IP Broadcasting
If a host does not have the IP address of a NetBIOS host in its cache, it broadcasts the NetBIOS name to the entire network.
LMHOSTS File
This is a text file that maps IP addresses to NetBIOS computer names.
NBNS
This is a NetBIOS Name Server that maps NetBIOS names to IP addresses.
Since NetBIOS name resolution mainly depends on broadcasts, the NetBEUI protocol creates significant network traffic if there are a large number of computers on the network. This protocol is used only on non routed Microsoft networks. Due to its severe limitations, it is rarely used even in Microsoft networks these days.
NetBEUI stands for NetBIOS Extended User Interface. It is an old Microsoft networking protocol used in small networks. This protocol provides services at the Transport and Network layer of the OSI model. It is not a routable protocol and cannot be used on large routed networks. It is easy to install and is the fastest of all protocols.
Computers using the NetBEUI protocol use NetBIOS naming conventions. NetBIOS computer names consist of a maximum of 15 characters, such a Server1 or Workstation1. NetBEUI uses the following three methods to resolve NetBIOS computer names to IP addresses:
IP Broadcasting
If a host does not have the IP address of a NetBIOS host in its cache, it broadcasts the NetBIOS name to the entire network.
LMHOSTS File
This is a text file that maps IP addresses to NetBIOS computer names.
NBNS
This is a NetBIOS Name Server that maps NetBIOS names to IP addresses.
Since NetBIOS name resolution mainly depends on broadcasts, the NetBEUI protocol creates significant network traffic if there are a large number of computers on the network. This protocol is used only on non routed Microsoft networks. Due to its severe limitations, it is rarely used even in Microsoft networks these days.
(ii) Internet Packet Exchange/Sequenced Packet Exchange (IPX/SPX)
IPX/SPX is a full protocol suite used in Novell NetWare networks. It is a fully routable protocol. Different protocols in this suite are as follows:
Service Advertising Protocol (SAP)
This protocol works at the application, presentation, and session layers, and it allows systems to advertise their services (such as file and print services).
NetWare Core Protocol (NCP)
This protocol works at the application, presentation, and session layers, and it allows client/server interactions (such as file and print sharing). NCP is a connection-oriented protocol.
Internet Packet Exchange (IPX)
This protocol works at the transport and network layers, and it provides network addressing and routing services. It is a connection-less protocol and provides fast and reliable communication between computers.
Sequenced Packet Exchange (SPX)
This protocol works at the Transport layer to provide connection-oriented services on top of the IPX protocol.
Routing Information Protocol (RIP)
This protocol works at the Network layer and is the default routing protocol for IPX/SPX networks. It uses the distance vector routing algorithm for calculating routes and building routing tables.
NetWare Link State Protocol (NLSP)
This protocol works at the Network layer to provide routing services based on a link state algorithm for calculating routes and building routing tables.
Open Data link Interface (ODI)
This protocol works at the Data Link layer to allow NetWare systems to work with any network interface card.
NetWare hostnames. In a NetWare network environment, only the servers are required to be assigned hostnames. These names consist of a maximum of 47 characters. The NetWare clients do not have hostnames. They use their IPX addresses instead.
IPX addresses. Logical NetWare networks are assigned 32-bit hexadecimal addresses. The servers and workstations use a 48-bit hexadecimal address that defaults to the MAC address of the network interface card. The node address is appended to the network address to create a unique node address in the internet- work. The following is an example of an IPX address:
0AC74E02:02254F89AE48
Note that the first part of the IPX address is the address of the logical network, and the second part is the unique MAC address of the network interface card. The colons from the MAC address are removed. Also, if there are any leading zeros, they are not written. Sometimes the IPX address is written as groups of four hexadecimal numbers separated by colons. The above address can thus be written as:
AC7:4E02:0225:4F89:AE48
NetWare frame types. When discussing the IPX/SPX protocol suite, it is important to include the frame types used in NetWare networks. If there is some connectivity problem between two systems using different versions, it is a good idea to check the frame types used on the network. NetWare uses the following types of frames for encapsulating data at the Data Link layer:
• NetWare 2.x and NetWare 3.x use IEEE 802.3 as the default frame type.
• NetWare 4.x uses IEEE 8.2.2 as the default frame type.
IPX/SPX interoperability and routing. The IPX/SPX protocol suite is fully routable and interoperates with many other protocols. Most notably, Microsoft operating systems include the NW Link IPX/SPX Compatible Protocol and the Microsoft Client for NetWare Networks for interoperability with Novell networks. Due to the increasing popularity and extended features of the TCP/IP protocol suite, the usage of IPX/SPX has declined significantly. Both Microsoft and Novell have made TCP/IP their default protocol.
IPX/SPX is a full protocol suite used in Novell NetWare networks. It is a fully routable protocol. Different protocols in this suite are as follows:
Service Advertising Protocol (SAP)
This protocol works at the application, presentation, and session layers, and it allows systems to advertise their services (such as file and print services).
NetWare Core Protocol (NCP)
This protocol works at the application, presentation, and session layers, and it allows client/server interactions (such as file and print sharing). NCP is a connection-oriented protocol.
Internet Packet Exchange (IPX)
This protocol works at the transport and network layers, and it provides network addressing and routing services. It is a connection-less protocol and provides fast and reliable communication between computers.
Sequenced Packet Exchange (SPX)
This protocol works at the Transport layer to provide connection-oriented services on top of the IPX protocol.
Routing Information Protocol (RIP)
This protocol works at the Network layer and is the default routing protocol for IPX/SPX networks. It uses the distance vector routing algorithm for calculating routes and building routing tables.
NetWare Link State Protocol (NLSP)
This protocol works at the Network layer to provide routing services based on a link state algorithm for calculating routes and building routing tables.
Open Data link Interface (ODI)
This protocol works at the Data Link layer to allow NetWare systems to work with any network interface card.
NetWare hostnames. In a NetWare network environment, only the servers are required to be assigned hostnames. These names consist of a maximum of 47 characters. The NetWare clients do not have hostnames. They use their IPX addresses instead.
IPX addresses. Logical NetWare networks are assigned 32-bit hexadecimal addresses. The servers and workstations use a 48-bit hexadecimal address that defaults to the MAC address of the network interface card. The node address is appended to the network address to create a unique node address in the internet- work. The following is an example of an IPX address:
0AC74E02:02254F89AE48
Note that the first part of the IPX address is the address of the logical network, and the second part is the unique MAC address of the network interface card. The colons from the MAC address are removed. Also, if there are any leading zeros, they are not written. Sometimes the IPX address is written as groups of four hexadecimal numbers separated by colons. The above address can thus be written as:
AC7:4E02:0225:4F89:AE48
NetWare frame types. When discussing the IPX/SPX protocol suite, it is important to include the frame types used in NetWare networks. If there is some connectivity problem between two systems using different versions, it is a good idea to check the frame types used on the network. NetWare uses the following types of frames for encapsulating data at the Data Link layer:
• NetWare 2.x and NetWare 3.x use IEEE 802.3 as the default frame type.
• NetWare 4.x uses IEEE 8.2.2 as the default frame type.
IPX/SPX interoperability and routing. The IPX/SPX protocol suite is fully routable and interoperates with many other protocols. Most notably, Microsoft operating systems include the NW Link IPX/SPX Compatible Protocol and the Microsoft Client for NetWare Networks for interoperability with Novell networks. Due to the increasing popularity and extended features of the TCP/IP protocol suite, the usage of IPX/SPX has declined significantly. Both Microsoft and Novell have made TCP/IP their default protocol.
(iii) AppleTalk
The Apple Talk protocol suite is used to interconnect Apple computers. Like IPX/ SPX and TCP/IP, this protocol is also fully routable. The Apple Talk protocol suite consists of the following different protocols:
AppleShare
This protocol works at the Application layer and provides file- and printer sharing services.
AppleTalk Filing Protocol (AFP)
This protocol works at the Presentation layer and is used to manage file sharing between AppleTalk hosts. It is also called Apple Filing Protocol.
AppleTalk Data Stream Protocol (ADSP)
This protocol works at the Application and Presentation layers, and provides services for establishing communication between AppleTalk hosts.
Zone Information Protocol (ZIP)
This protocol works at the Session layer to divide an AppleTalk network into zones.
AppleTalk Session Protocol (ASP)
This protocol works at the Session layer to establish and terminate connections between hosts.
Printer Access Protocol (PAP)
This protocol works at the Session layer to provide printing services on an AppleTalk network.
AppleTalk Address Resolution Protocol (ARP)
This protocol works at the Network layer to resolve AppleTalk addresses to Ethernet or Token Ring addresses.
Datagram Delivery Protocol (DDP)
This protocol works at the Network layer to handle routing functions and delivery of datagrams.
AppleTalk Transaction Protocol (ATP)
This protocol works at the Transport layer to provide a connectionless session between hosts.
Name Binding Protocol (NBP)
This protocol also works at the Transport layer to map AppleTalk hostnames to network layer addresses.
Routing Table Maintenance Protocol (RTMP)
This protocol works at the Transport layer to maintain routing tables.
Ether Talk Link Access Protocol (ELAP)
This protocol works at the Data Link layer and provides compatibility with Ethernet protocol.
Token Talk Link Access protocol (TLAP)
This protocol works at the Data Link layer and provides compatibility with Token Ring protocol.
AppleTalk addressing and naming. An Apple Talk host address consists of a 24-bit long number with 16 bits assigned to the network and 8 bits assigned to the host. This address is expressed in a decimal format. An administrator assigns the network address while the host address is automatically generated by the system when it is first started. It is a randomly generated number and is broadcast to the entire AppleTalk network as soon as it is generated. An example of an AppleTalk address is 5.48, where 5 is the network address and 48 is the host address. Apple Talk hostnames are resolved using the Name Binding Protocol (NBP), which is similar to the Domain Name System (DNS) used on TCP/IP networks.
AppleTalk interoperability and routing. Apple Talk is a fully routable protocol but cannot be used on the Internet. The Routing Table Maintenance protocol provides a functionality that is similar to the RIP used on TCP/IP networks. Unix/Linux and Microsoft operating systems have limited support for Apple Talk networks. As with the IPX/SPX protocol suite, the AppleTalk protocol is also losing ground due to the increasing popularity of the TCP/IP protocol.
The Apple Talk protocol suite is used to interconnect Apple computers. Like IPX/ SPX and TCP/IP, this protocol is also fully routable. The Apple Talk protocol suite consists of the following different protocols:
AppleShare
This protocol works at the Application layer and provides file- and printer sharing services.
AppleTalk Filing Protocol (AFP)
This protocol works at the Presentation layer and is used to manage file sharing between AppleTalk hosts. It is also called Apple Filing Protocol.
AppleTalk Data Stream Protocol (ADSP)
This protocol works at the Application and Presentation layers, and provides services for establishing communication between AppleTalk hosts.
Zone Information Protocol (ZIP)
This protocol works at the Session layer to divide an AppleTalk network into zones.
AppleTalk Session Protocol (ASP)
This protocol works at the Session layer to establish and terminate connections between hosts.
Printer Access Protocol (PAP)
This protocol works at the Session layer to provide printing services on an AppleTalk network.
AppleTalk Address Resolution Protocol (ARP)
This protocol works at the Network layer to resolve AppleTalk addresses to Ethernet or Token Ring addresses.
Datagram Delivery Protocol (DDP)
This protocol works at the Network layer to handle routing functions and delivery of datagrams.
AppleTalk Transaction Protocol (ATP)
This protocol works at the Transport layer to provide a connectionless session between hosts.
Name Binding Protocol (NBP)
This protocol also works at the Transport layer to map AppleTalk hostnames to network layer addresses.
Routing Table Maintenance Protocol (RTMP)
This protocol works at the Transport layer to maintain routing tables.
Ether Talk Link Access Protocol (ELAP)
This protocol works at the Data Link layer and provides compatibility with Ethernet protocol.
Token Talk Link Access protocol (TLAP)
This protocol works at the Data Link layer and provides compatibility with Token Ring protocol.
AppleTalk addressing and naming. An Apple Talk host address consists of a 24-bit long number with 16 bits assigned to the network and 8 bits assigned to the host. This address is expressed in a decimal format. An administrator assigns the network address while the host address is automatically generated by the system when it is first started. It is a randomly generated number and is broadcast to the entire AppleTalk network as soon as it is generated. An example of an AppleTalk address is 5.48, where 5 is the network address and 48 is the host address. Apple Talk hostnames are resolved using the Name Binding Protocol (NBP), which is similar to the Domain Name System (DNS) used on TCP/IP networks.
AppleTalk interoperability and routing. Apple Talk is a fully routable protocol but cannot be used on the Internet. The Routing Table Maintenance protocol provides a functionality that is similar to the RIP used on TCP/IP networks. Unix/Linux and Microsoft operating systems have limited support for Apple Talk networks. As with the IPX/SPX protocol suite, the AppleTalk protocol is also losing ground due to the increasing popularity of the TCP/IP protocol.
(iv) Transmission Control Protocol/Internet Protocol (TCP/IP)
The TCP/IP is a set of several protocols. It is the most widely used protocol suite in private networks as well as on the Internet. Unlike the AppleTalk and IPX/SPX protocols, TCP/IP is not proprietary to any organization, but is a public protocol suite. Some of the well-known protocols and their functions are discussed in this section. The TCP/IP protocol suite is a set of a number of protocols and services, each with a specific function working at one or more layers of the networking model. Some of the commonly used protocols and their functions are listed here:
Internet Protocol (IP)
IP is a connection-less protocol that works at the network layer to provide IP addressing and routing functions.
Transmission Control Protocol (TCP)
TCP is a connection-oriented protocol that works at the transport layer to provide guaranteed delivery, flow control, error detection, error correction, and packet sequencing.
User Datagram Protocol (UDP)
UDP is a connection-less protocol that works at the transport layer but does not provide guaranteed delivery of data. It does not perform any error checking or correction and hence is faster and consumes less network bandwidth than TCP.
File Transfer Protocol (FTP)
The TCP/IP is a set of several protocols. It is the most widely used protocol suite in private networks as well as on the Internet. Unlike the AppleTalk and IPX/SPX protocols, TCP/IP is not proprietary to any organization, but is a public protocol suite. Some of the well-known protocols and their functions are discussed in this section. The TCP/IP protocol suite is a set of a number of protocols and services, each with a specific function working at one or more layers of the networking model. Some of the commonly used protocols and their functions are listed here:
Internet Protocol (IP)
IP is a connection-less protocol that works at the network layer to provide IP addressing and routing functions.
Transmission Control Protocol (TCP)
TCP is a connection-oriented protocol that works at the transport layer to provide guaranteed delivery, flow control, error detection, error correction, and packet sequencing.
User Datagram Protocol (UDP)
UDP is a connection-less protocol that works at the transport layer but does not provide guaranteed delivery of data. It does not perform any error checking or correction and hence is faster and consumes less network bandwidth than TCP.
File Transfer Protocol (FTP)
FTP works at the Application layer to provide file transfers between remote computers. FTP uses TCP as its transport protocol and is a client/server application that authenticates users before allowing access to servers that host the FTP service. Most FTP servers allow anonymous logon that enables multiple users to connect to the server and download files. FTP is commonly used on the Internet for file downloads. One of the major limitations of the this protocol is security. The authentication method uses clear-text usernames and passwords, which is a serious security concern.
Secure File Transfer Protocol (SFTP)
SFTP is the secure version of FTP protocol. It is used to transfer data in an encrypted format between the client and the server. Secure Shell (SSH) is used to provide secure authentication between the two computers.
Trivial File Transfer Protocol (TFTP)
TFTP is an Application-layer protocol used to transfer files between two remote computers. It is limited in functionality compared to FTP. It uses UDP as its transport protocol and is hence less reliable, but faster than, FTP.
Simple Mail Transfer Protocol (SMTP)
SMTP is a connection-oriented Application-layer protocol that is used to transport messages between remote email servers. It uses TCP at the transport layer and hence guarantees delivery of data.
HyperText Transfer Protocol (HTTP)
HTTP is an Application-layer protocol that allows text, images, and multimedia to be downloaded from web sites. It is also a connection-oriented protocol that uses TCP at the transport layer. HTTP works with a Uniform Resource Locator (URL) to connect to the desired web site. An example of a
URL is http://www.oreilly.com.
HTTP Secure (HTTPS)
HTTPS is the secure version of the HTTP protocol that allows servers and clients to be authenticated before the communication session starts. This protocol is also an Application layer protocol and uses TCP at the Transport layer. It is commonly used for online banking and other e-commerce functions. It uses the secure socket layer (SSL) to encrypt the network traffic between the web server and the web client. A web site using SSL has a URL starting with https://.
Post Office Protocol 3 (POP3)
POP3 is used to download or retrieve email messages from mail servers running the SMTP protocol. One of the limitations of the POP3 protocol is that it uses clear-text usernames and passwords, which is a serious security concern.
Internet Message Access Protocol 4 (IMAP4)
Like POP3, IMAP4 is also used to retrieve email from mail servers. The advantage of using IMAP4 over POP3 is that it provides a secure authentication mechanism.
Telnet
Telnet is an Application-layer protocol that allows connections to remote hosts. Administrators use this protocol to connect remotely to network devices and run commands in order to configure or maintain them. This is also a connection-oriented protocol and uses TCP at the Transport layer.
Secure Shell (SSH)
SSH is the secure alternative to connecting to remote systems or devices instead of using Telnet. It provides strong authentication mechanisms and encryption of information between two remote hosts.
Internet Control Message Protocol (ICMP)
ICMP works at the Network layer to provide error checking and reporting functions. It is a connection-less protocol and uses IP for providing best-effort delivery. It is used in network management and maintenance systems. For example, ping is a troubleshooting utility that uses the ICMP protocol.
Address Resolution Protocol (ARP)
ARP works at the Network layer and is used to resolve IP addresses to MAC addresses. Upper-layer protocols use ARP to correctly deliver data packets to the destination host. ARP maintains a mapping (called the ARP cache)of IP addresses and MAC addresses in the system memory. If the ARP cache does not have an entry for a requested IP address, it broadcasts the IP address on the local network to find out which host has the specified IP address.
Reverse Address Resolution Protocol (RARP)
The function of RARP is opposite to that of the ARP. It is used to obtain the IP address of a host whose MAC address is known.
Network Time Protocol (NTP)
NTP is used to exchange time information between TCP/IP hosts. One of the systems is usually configured as a time provider, which uses NTP to transmit time information to other hosts.
Network News Transfer Protocol (NNTP)
NNTP works at the application layer to provide newsgroup services such as posting and retrieving messages on discussion forums. It uses TCP at the Transport layer.
Secure Copy Protocol (SCP)
SCP works at the Application layer to enable secure copying of files from Unix/Linux systems. It uses SSH technology for a secure information exchange between two systems. It is a safe alternative to the Remote Copy Protocol (RCP).
Lightweight Directory Access Protocol (LDAP)
LDAP is an Application-layer protocol that enables users to access and query directory services such as Microsoft’s Active Directory, Novell’s e-Directory, and Novell Directory Services (NDS). LDAP functions can be performed from the command line or from graphic user interfaces (GUIs).
Internet Group Management Protocol (IGMP)
IGMP works at the network layer of the OSI model and is used to register and discover network devices in a multicasting group. IGMP enables devices to exchange messages within the members (network devices) of a multicasting group.
Line Printer Remote (LPR)
LPR works at the application layer to provide client connectivity to printers in all major network operating systems, such as Unix/Linux and Windows. Line Printer Daemon (LPD) is a server component that accepts client print requests sent using the LPR application.
SFTP is the secure version of FTP protocol. It is used to transfer data in an encrypted format between the client and the server. Secure Shell (SSH) is used to provide secure authentication between the two computers.
Trivial File Transfer Protocol (TFTP)
TFTP is an Application-layer protocol used to transfer files between two remote computers. It is limited in functionality compared to FTP. It uses UDP as its transport protocol and is hence less reliable, but faster than, FTP.
Simple Mail Transfer Protocol (SMTP)
SMTP is a connection-oriented Application-layer protocol that is used to transport messages between remote email servers. It uses TCP at the transport layer and hence guarantees delivery of data.
HyperText Transfer Protocol (HTTP)
HTTP is an Application-layer protocol that allows text, images, and multimedia to be downloaded from web sites. It is also a connection-oriented protocol that uses TCP at the transport layer. HTTP works with a Uniform Resource Locator (URL) to connect to the desired web site. An example of a
URL is http://www.oreilly.com.
HTTP Secure (HTTPS)
HTTPS is the secure version of the HTTP protocol that allows servers and clients to be authenticated before the communication session starts. This protocol is also an Application layer protocol and uses TCP at the Transport layer. It is commonly used for online banking and other e-commerce functions. It uses the secure socket layer (SSL) to encrypt the network traffic between the web server and the web client. A web site using SSL has a URL starting with https://.
Post Office Protocol 3 (POP3)
POP3 is used to download or retrieve email messages from mail servers running the SMTP protocol. One of the limitations of the POP3 protocol is that it uses clear-text usernames and passwords, which is a serious security concern.
Internet Message Access Protocol 4 (IMAP4)
Like POP3, IMAP4 is also used to retrieve email from mail servers. The advantage of using IMAP4 over POP3 is that it provides a secure authentication mechanism.
Telnet
Telnet is an Application-layer protocol that allows connections to remote hosts. Administrators use this protocol to connect remotely to network devices and run commands in order to configure or maintain them. This is also a connection-oriented protocol and uses TCP at the Transport layer.
Secure Shell (SSH)
SSH is the secure alternative to connecting to remote systems or devices instead of using Telnet. It provides strong authentication mechanisms and encryption of information between two remote hosts.
Internet Control Message Protocol (ICMP)
ICMP works at the Network layer to provide error checking and reporting functions. It is a connection-less protocol and uses IP for providing best-effort delivery. It is used in network management and maintenance systems. For example, ping is a troubleshooting utility that uses the ICMP protocol.
Address Resolution Protocol (ARP)
ARP works at the Network layer and is used to resolve IP addresses to MAC addresses. Upper-layer protocols use ARP to correctly deliver data packets to the destination host. ARP maintains a mapping (called the ARP cache)of IP addresses and MAC addresses in the system memory. If the ARP cache does not have an entry for a requested IP address, it broadcasts the IP address on the local network to find out which host has the specified IP address.
Reverse Address Resolution Protocol (RARP)
The function of RARP is opposite to that of the ARP. It is used to obtain the IP address of a host whose MAC address is known.
Network Time Protocol (NTP)
NTP is used to exchange time information between TCP/IP hosts. One of the systems is usually configured as a time provider, which uses NTP to transmit time information to other hosts.
Network News Transfer Protocol (NNTP)
NNTP works at the application layer to provide newsgroup services such as posting and retrieving messages on discussion forums. It uses TCP at the Transport layer.
Secure Copy Protocol (SCP)
SCP works at the Application layer to enable secure copying of files from Unix/Linux systems. It uses SSH technology for a secure information exchange between two systems. It is a safe alternative to the Remote Copy Protocol (RCP).
Lightweight Directory Access Protocol (LDAP)
LDAP is an Application-layer protocol that enables users to access and query directory services such as Microsoft’s Active Directory, Novell’s e-Directory, and Novell Directory Services (NDS). LDAP functions can be performed from the command line or from graphic user interfaces (GUIs).
Internet Group Management Protocol (IGMP)
IGMP works at the network layer of the OSI model and is used to register and discover network devices in a multicasting group. IGMP enables devices to exchange messages within the members (network devices) of a multicasting group.
Line Printer Remote (LPR)
LPR works at the application layer to provide client connectivity to printers in all major network operating systems, such as Unix/Linux and Windows. Line Printer Daemon (LPD) is a server component that accepts client print requests sent using the LPR application.
Port assignments in TCP/IP
Every application, service, or protocol in the TCP/IP suite has a specific port number assigned to it. A port is like a socket that the application uses to send or receive data packets. When a computer receives a data packet, it checks the associated port number to determine which application will receive the data. For example, the FTP service uses port numbers 20 and 21. TCP/IP port numbers fall in following three categories:
• Well-known port numbers range from 0 to 1,023.
• User ports (registered ports) range from 1,024 to 46,151.
• Dynamic/private ports range from 46,152 to 65,535.
Every application, service, or protocol in the TCP/IP suite has a specific port number assigned to it. A port is like a socket that the application uses to send or receive data packets. When a computer receives a data packet, it checks the associated port number to determine which application will receive the data. For example, the FTP service uses port numbers 20 and 21. TCP/IP port numbers fall in following three categories:
• Well-known port numbers range from 0 to 1,023.
• User ports (registered ports) range from 1,024 to 46,151.
• Dynamic/private ports range from 46,152 to 65,535.
TCP/IP addressing. Hosts in a TCP/IP network follow IP addressing schemes. IPv4 is the current and most commonly used version of IP address. The IP address consists of 32 bits and is expressed as decimal numbers separated by a period. This is called the dotted decimal notation. An IP address is composed of four sets of eight bytes (octet) each. 192.168.2.10 is an example of an IP address.
Since a TCP/IP network can be composed of several segments, it becomes necessary to identify the network segment in which a particular host is located. For this purpose, a second 32-bit number is associated with an IP address. This number is used to identify the network address from the host address, and is called the subnet mask. When converted to a binary number, the network part is assigned a binary value of 1 and the host part is assigned a value of 0 in the subnet mask. For example, if the subnet mask is 255.255.0.0, the first 16 bits of the IP address would represent the network address, and the last 16 bits would represent the host address.
IP addresses are divided into classes A, B, C, D, and E. Out of these, classes A, B, and C are available for assignment to private organizations. IP addresses can further be divided into public (registered) or private (unregistered) addresses. Organizations using public addresses can be connected to the Internet, while the private IP addresses can only be used internally.
Since a TCP/IP network can be composed of several segments, it becomes necessary to identify the network segment in which a particular host is located. For this purpose, a second 32-bit number is associated with an IP address. This number is used to identify the network address from the host address, and is called the subnet mask. When converted to a binary number, the network part is assigned a binary value of 1 and the host part is assigned a value of 0 in the subnet mask. For example, if the subnet mask is 255.255.0.0, the first 16 bits of the IP address would represent the network address, and the last 16 bits would represent the host address.
IP addresses are divided into classes A, B, C, D, and E. Out of these, classes A, B, and C are available for assignment to private organizations. IP addresses can further be divided into public (registered) or private (unregistered) addresses. Organizations using public addresses can be connected to the Internet, while the private IP addresses can only be used internally.
TCP/IP naming. TCP/IP hosts can be identified either by their IP addresses or by their hostnames. A DNS server performs the translation of IP addresses to computer names. In smaller networks, a text file named hosts can also be created on every computer to provide name resolution.
TCP/IP routing. Needless to say, TCP/IP is a fully routable protocol. The routing functionality is provided by a number of routing protocols, such as RIP and OSPF.
TCP/IP interoperability. The TCP/IP protocol suite is supported by all major network and desktop operating systems. Apart from Unix/Linux operating systems, Microsoft, Apple, and NetWare have also made TCP/IP their default protocols. As of now, TCP/IP is the most versatile and feature-rich protocol suite available in all operating system environments.
TCP/IP routing. Needless to say, TCP/IP is a fully routable protocol. The routing functionality is provided by a number of routing protocols, such as RIP and OSPF.
TCP/IP interoperability. The TCP/IP protocol suite is supported by all major network and desktop operating systems. Apart from Unix/Linux operating systems, Microsoft, Apple, and NetWare have also made TCP/IP their default protocols. As of now, TCP/IP is the most versatile and feature-rich protocol suite available in all operating system environments.
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