Protocols
A protocol is a set of rules and guidelines for communicating data. Rules are defined for each step and process during communication between two or more computers. Networks have to follow these rules to successfully transmit data.
Similar to programming languages, protocols are based on specific rules and regulations for computing and are designed for efficiency. Each rule is defined in different terms and is assigned a unique name. Protocols specify the standards for communication and provide detailed information on processes involved in data transmission. Such processes include:
- Type of task
- Process nature
- Data flow rate
- Data type
- Device management
A single process can be handled by more than one protocol simultaneously. This coordination of protocols creates a protocol family.
In Other Words:-
An agreed-upon format for transmitting data between two devices. The protocol determines the following:
· the type of error checking to be used
· data compression method, if any
· how the sending device will indicate that it has finished sending a message
· how the receiving device will indicate that it has received a message
There are a variety of standard protocols from which programmers can choose. Each has particular advantages and disadvantages; for example, some are simpler than others, some are more reliable, and some are faster.
From a user's point of view, the only interesting aspect about protocols is that your computer or device must support the right ones if you want to communicate with other computers. The protocol can be implemented either in hardware or in software.
Different Types of Protocols are as follows:-
1. TCP
Transmission Control Protocol (TCP) A connection-oriented transport protocol. Connection-oriented transport protocols provide reliable transport, in that if a segment is dropped, the sender can detect that drop and retransmit that dropped
segment. Specifically, a receiver acknowledges segments that it receives. Based on those acknowledgments, a sender can determine which segments were successfully
received.
TCP operates at the transport layer of the OSI model.
segment. Specifically, a receiver acknowledges segments that it receives. Based on those acknowledgments, a sender can determine which segments were successfully
received.
TCP operates at the transport layer of the OSI model.
TCP three-way handshake.
It sends a message called a SYN to the target host.2. The target host opens a connection for the request and sends back an acknowledgment message called an ACK (or SYN ACK).
1. 3. The host that originated the request sends back another acknowledgment, saying that it has received the ACK message and that the session is ready to be used to transfer data.
UDP
User Datagram Protocol A connectionless transport protocol. Connectionless transport protocols provide unreliable transport, in that if a segment is dropped, the sender is unaware of the drop, and no retransmission occurs.
UDP operates at the transport layer
UDP operates at the transport layer
FTP
File Transfer Protocol (FTP)
Works at the Application layer
FTP provides for the uploading and downloading of files from a remote host running FTP server software. As well as uploading and downloading files, FTP enables you to view the contents of folders on an FTP server and rename and delete files and directories if you have the necessary permissions.
One of the big problems associated with FTP is that it is considered insecure. Even though simple authentication methods are associated with FTP, it is still susceptible to relatively simple hacking approaches. In addition, FTP transmits data between the sender and receiver in an unencrypted format.
Works at the Application layer
FTP provides for the uploading and downloading of files from a remote host running FTP server software. As well as uploading and downloading files, FTP enables you to view the contents of folders on an FTP server and rename and delete files and directories if you have the necessary permissions.
One of the big problems associated with FTP is that it is considered insecure. Even though simple authentication methods are associated with FTP, it is still susceptible to relatively simple hacking approaches. In addition, FTP transmits data between the sender and receiver in an unencrypted format.
Commonly Used FTP Commands
ls -Lists the files in the current directory on the remote system
cd -Changes the working directory on the remote host
lcd -Changes the working directory on the local host
put -Uploads a single file to the remote host
get -Downloads a single file from the remote host
mput -Uploads multiple files to the remote host
mget -Downloads multiple files from the remote host
binary- Switches transfers into binary mode
ascii -Switches transfers into ASCII mode (the default)
cd -Changes the working directory on the remote host
lcd -Changes the working directory on the local host
put -Uploads a single file to the remote host
get -Downloads a single file from the remote host
mput -Uploads multiple files to the remote host
mget -Downloads multiple files from the remote host
binary- Switches transfers into binary mode
ascii -Switches transfers into ASCII mode (the default)
SFTP
Secure File Transfer Protocol
A protocol that transfers files between clients securely, Based on Secure Shell (SSH) technology provides robust authentication between the sender and receiver. It also provides encryption capabilities, which means that even if packets are copied from the network, their contents remain hidden
from prying eyes.
A protocol that transfers files between clients securely, Based on Secure Shell (SSH) technology provides robust authentication between the sender and receiver. It also provides encryption capabilities, which means that even if packets are copied from the network, their contents remain hidden
from prying eyes.
TFTP
Trivial File Transfer Protocol
A variation on FTP is TFTP, which is also a file transfer mechanism. However, TFTP does not have the security capability or the level of functionality that FTP has. TFTP, is most often associated with simple downloads, such as those associated with transferring firmware to a device such as a router and booting diskless workstations.
Another feature that TFTP does not offer is directory navigation.
TFTP is an application layer protocol that uses UDP, which is a connectionless transport layer protocol. For this reason, TFTP is called a connectionless file transfer method.
A variation on FTP is TFTP, which is also a file transfer mechanism. However, TFTP does not have the security capability or the level of functionality that FTP has. TFTP, is most often associated with simple downloads, such as those associated with transferring firmware to a device such as a router and booting diskless workstations.
Another feature that TFTP does not offer is directory navigation.
TFTP is an application layer protocol that uses UDP, which is a connectionless transport layer protocol. For this reason, TFTP is called a connectionless file transfer method.
SMTP
Simple Mail Transfer Protocol
SMTP is a protocol that defines how mail messages
are sent between hosts. SMTP uses TCP connections to guarantee error-free delivery of messages. SMTP is not overly sophisticated and requires that the destination host always be available.
SMTP can be used to both send and receive mail. Post Office Protocol version 3 (POP3) and Internet Message Access Protocol version 4 (IMAP4) can be used only to receive mail.
SMTP is a protocol that defines how mail messages
are sent between hosts. SMTP uses TCP connections to guarantee error-free delivery of messages. SMTP is not overly sophisticated and requires that the destination host always be available.
SMTP can be used to both send and receive mail. Post Office Protocol version 3 (POP3) and Internet Message Access Protocol version 4 (IMAP4) can be used only to receive mail.
HTTP
Hypertext Transfer Protocol
HTTP is the protocol that enables text, graphics, multimedia, and other material to be downloaded from an HTTP server. HTTP defines what actions can be requested by clients and how servers should answer those requests.
HTTP is a connection-oriented protocol that uses TCP as a transport protocol.
HTTP is the protocol that enables text, graphics, multimedia, and other material to be downloaded from an HTTP server. HTTP defines what actions can be requested by clients and how servers should answer those requests.
HTTP is a connection-oriented protocol that uses TCP as a transport protocol.
HTTPS
Hypertext Transfer Protocol Secure
One of the downsides of using HTTP is that HTTP requests are sent in clear text. For some applications, such as e-commerce, this method to exchange information is unsuitable—a more secure method is needed. The solution is
HTTPS, which uses a system known as Secure Socket Layer (SSL), which encrypts the information sent between the client and host.
One of the downsides of using HTTP is that HTTP requests are sent in clear text. For some applications, such as e-commerce, this method to exchange information is unsuitable—a more secure method is needed. The solution is
HTTPS, which uses a system known as Secure Socket Layer (SSL), which encrypts the information sent between the client and host.
POP3
Post Office Protocol Version 3
A mechanism for downloading, or pulling, email from a server. They are necessary because although the mail is transported around the network via SMTP, users cannot always immediately read it, so it must be stored in a central location. From this location, it needs to be downloaded
or retrieved, which is what POP3 enables you to do.
One of the problems with POP3 is that the password used to access a mailbox is transmitted across the network in cleartext. This means that if people want to, they could determine your POP3 password with relative ease.
A mechanism for downloading, or pulling, email from a server. They are necessary because although the mail is transported around the network via SMTP, users cannot always immediately read it, so it must be stored in a central location. From this location, it needs to be downloaded
or retrieved, which is what POP3 enables you to do.
One of the problems with POP3 is that the password used to access a mailbox is transmitted across the network in cleartext. This means that if people want to, they could determine your POP3 password with relative ease.
IMAP4
Internet Message Access Protocol Version 4
A mechanism for downloading, or pulling, email from a server. They are necessary because although the mail is transported around the network via SMTP, users cannot always immediately read it, so it must be stored in a central location. From this location, it needs to be downloaded
or retrieved, which is what IMAP4 enables you to do.
IMAP4 offers an advantage over POP3. It uses a more sophisticated authentication system, which makes it more difficult for people to determine a password.
A mechanism for downloading, or pulling, email from a server. They are necessary because although the mail is transported around the network via SMTP, users cannot always immediately read it, so it must be stored in a central location. From this location, it needs to be downloaded
or retrieved, which is what IMAP4 enables you to do.
IMAP4 offers an advantage over POP3. It uses a more sophisticated authentication system, which makes it more difficult for people to determine a password.
Telnet
Telnet is a virtual terminal protocol. It enables sessions to be opened on a remote host, and then commands can be executed on that remote host. For many years, Telnet was the method by which clients accessed multiuser systems such as mainframes and minicomputers. It also was the connection method of choice for UNIX systems. Today, Telnet is still
commonly used to access routers and other managed network devices.
One of the problems with Telnet is that it is not secure. As a result, remote session functionality is now almost always achieved by using alternatives such as SSH.
commonly used to access routers and other managed network devices.
One of the problems with Telnet is that it is not secure. As a result, remote session functionality is now almost always achieved by using alternatives such as SSH.
SSH
Secure Shell (SSH) is a secure alternative to Telnet. SSH provides security by encrypting data as it travels between systems. This makes it difficult for hackers using
packet sniffers and other traffic-detection systems. It also provides more robust authentication systems than Telnet.
Two versions of SSH are available: SSH1 and SSH2. Of the two, SSH2 is considered more secure. The two versions are incompatible. If you use an SSH client program, the server implementation of SSH that you connect to must be the same version. Although SSH, like Telnet, is associated primarily with UNIX and Linux systems, implementations of SSH are available for all commonly used computing platforms, including Windows and Macintosh. As discussed earlier, SSH is the foundational technology for the Secure File Transfer Protocol (SFTP).
packet sniffers and other traffic-detection systems. It also provides more robust authentication systems than Telnet.
Two versions of SSH are available: SSH1 and SSH2. Of the two, SSH2 is considered more secure. The two versions are incompatible. If you use an SSH client program, the server implementation of SSH that you connect to must be the same version. Although SSH, like Telnet, is associated primarily with UNIX and Linux systems, implementations of SSH are available for all commonly used computing platforms, including Windows and Macintosh. As discussed earlier, SSH is the foundational technology for the Secure File Transfer Protocol (SFTP).
ICMP
Internet Control Message Protocol
ICMP Is a protocol that works with the IP layer to provide error checking and reporting functionality. In effect, ICMP is a tool that IP uses in its quest to provide best-effort delivery.
ICMP can be used for a number of functions. Its most common function is probably the widely used and incredibly useful ping utility, which can send a stream of ICMP echo requests to a remote host.
ICMP also can return error messages such as Destination unreachable and Time exceeded. (The former message is reported when a destination cannot be contacted and the latter when the Time To Live [TTL] of a datagram has been exceeded.)
ICMP performs source quench. In a source quench scenario, the receiving host cannot handle the influx of data at the same rate as the data is sent. To slow down the sending host, the receiving host sends ICMP source quench messages, telling the sender to slow down. This action prevents packets from dropping and having to be re-sent.
ICMP Is a protocol that works with the IP layer to provide error checking and reporting functionality. In effect, ICMP is a tool that IP uses in its quest to provide best-effort delivery.
ICMP can be used for a number of functions. Its most common function is probably the widely used and incredibly useful ping utility, which can send a stream of ICMP echo requests to a remote host.
ICMP also can return error messages such as Destination unreachable and Time exceeded. (The former message is reported when a destination cannot be contacted and the latter when the Time To Live [TTL] of a datagram has been exceeded.)
ICMP performs source quench. In a source quench scenario, the receiving host cannot handle the influx of data at the same rate as the data is sent. To slow down the sending host, the receiving host sends ICMP source quench messages, telling the sender to slow down. This action prevents packets from dropping and having to be re-sent.
ARP
Address Resolution Protocol (ARP)
ARP, is responsible for resolving IP addresses to Media Access Control (MAC) addresses. When a system attempts to contact another host, IP first determines whether the other host is on the same network it is on by looking at the IP address. If IP determines that the destination is on the local network, it consults the ARP cache to see whether it has a
corresponding entry. The ARP cache is a table on the local system that stores mappings between data link layer addresses (the MAC address or physical address) and network layer addresses (IP addresses).
RARP
Reverse Address Resolution Protocol (RARP)
Performs the same function as ARP, but in reverse. In other words, it resolves MAC addresses to IP addresses.
RARP makes it possible for applications or systems to learn their own IP address from a router or Domain Name Service (DNS) server. Such a resolution is useful for tasks such as performing reverse lookups in DNS.
Performs the same function as ARP, but in reverse. In other words, it resolves MAC addresses to IP addresses.
RARP makes it possible for applications or systems to learn their own IP address from a router or Domain Name Service (DNS) server. Such a resolution is useful for tasks such as performing reverse lookups in DNS.
NTP
Network Time Protocol
NTP is the part of the TCP/IP protocol suite that facilitates the communication of time between systems. The idea is that
one system configured as a time provider transmits time information to other systems that can be both time receivers and time providers for other systems.
NTP is the part of the TCP/IP protocol suite that facilitates the communication of time between systems. The idea is that
one system configured as a time provider transmits time information to other systems that can be both time receivers and time providers for other systems.
NNTP
Network News Transfer Protocol
Is a protocol associated with posting and retrieving messages to and from newsgroups. A newsgroup is a discussion
forum hosted on a remote system. By using NNTP client software, like that included with many common email clients, users can post, reply to, and retrieve messages.
Although web-based discussion forums are slowly replacing newsgroups, demand for newsgroup access remains high.
The distinction between web based discussion forums and NNTP newsgroups is that messages are retrieved
from the server to be read. In contrast, on a web-based discussion forum, the messages are not downloaded. They are simply viewed from a remote location.
Is a protocol associated with posting and retrieving messages to and from newsgroups. A newsgroup is a discussion
forum hosted on a remote system. By using NNTP client software, like that included with many common email clients, users can post, reply to, and retrieve messages.
Although web-based discussion forums are slowly replacing newsgroups, demand for newsgroup access remains high.
The distinction between web based discussion forums and NNTP newsgroups is that messages are retrieved
from the server to be read. In contrast, on a web-based discussion forum, the messages are not downloaded. They are simply viewed from a remote location.
SCP
Secure Copy Protocol
Secure Copy Protocol (SCP) is another protocol based on SSH technology. SCP provides a secure means to copy files between systems on a network. By using SSH technology, it encrypts data as it travels across the network, thereby
securing it from eavesdropping. It is intended as a more secure substitute for Remote Copy Protocol (RCP). SCP is available as a command-line utility, or as part of application software for most commonly used computing platforms.
Secure Copy Protocol (SCP) is another protocol based on SSH technology. SCP provides a secure means to copy files between systems on a network. By using SSH technology, it encrypts data as it travels across the network, thereby
securing it from eavesdropping. It is intended as a more secure substitute for Remote Copy Protocol (RCP). SCP is available as a command-line utility, or as part of application software for most commonly used computing platforms.
LDAP
Lightweight Directory Access Protocol
Lightweight Directory Access Protocol (LDAP) is a protocol that provides a mechanism to access and query directory services systems. In the context of the Network+ exam, these directory services systems are most likely to be Novell
Directory Services (NDS) and Microsoft's Active Directory. Although LDAP supports command-line queries executed directly against the directory database, most LDAP interactions are via utilities such as an authentication program
(network logon) or locating a resource in the directory through a search utility.
Lightweight Directory Access Protocol (LDAP) is a protocol that provides a mechanism to access and query directory services systems. In the context of the Network+ exam, these directory services systems are most likely to be Novell
Directory Services (NDS) and Microsoft's Active Directory. Although LDAP supports command-line queries executed directly against the directory database, most LDAP interactions are via utilities such as an authentication program
(network logon) or locating a resource in the directory through a search utility.
IGMP
Internet Group Management Protocol
The protocol within the TCP/IP protocol suite that manages multicast groups. It enables, for example, one computer on the Internet to target content to a specific group of computers
that will receive content from the sending system.
IGMP is used to register devices into a multicast group, as well as to discover what other devices on the network are members of the same multicast group. Common applications for multicasting include groups of routers on an internetwork
and videoconferencing clients.
The protocol within the TCP/IP protocol suite that manages multicast groups. It enables, for example, one computer on the Internet to target content to a specific group of computers
that will receive content from the sending system.
IGMP is used to register devices into a multicast group, as well as to discover what other devices on the network are members of the same multicast group. Common applications for multicasting include groups of routers on an internetwork
and videoconferencing clients.
TLS
Transport Layer Security
A security protocol designed to ensure privacy between communicating client/server applications. When a server and client communicate, TLS ensures that no one can eavesdrop and intercept or otherwise tamper with the data message. TLS is the successor to SSL.
TLS record protocol: Uses a reliable transport protocol such as TCP and ensures that the connection made between systems is private using data encryption.
TLS handshake protocol: Used for authentication between the client and server.
A security protocol designed to ensure privacy between communicating client/server applications. When a server and client communicate, TLS ensures that no one can eavesdrop and intercept or otherwise tamper with the data message. TLS is the successor to SSL.
TLS record protocol: Uses a reliable transport protocol such as TCP and ensures that the connection made between systems is private using data encryption.
TLS handshake protocol: Used for authentication between the client and server.
SIP
Session Initiation Protocol
An application layer protocol designed to establish and maintain multimedia sessions, such as Internet telephony calls. This means that SIP can create communication sessions for such features as audio/videoconferencing, online gaming, and person-to-person conversations over the Internet. SIP does not operate alone; it uses TCP or UDP as a transport protocol.
An application layer protocol designed to establish and maintain multimedia sessions, such as Internet telephony calls. This means that SIP can create communication sessions for such features as audio/videoconferencing, online gaming, and person-to-person conversations over the Internet. SIP does not operate alone; it uses TCP or UDP as a transport protocol.
RTP
The Real-time Transport Protocol
is the Internet-standard protocol for the transport of real-time data, including audio and video. RTP can use either TCP or UDP as a transport mechanism. However, UDP is used more
often because applications using RTP are less sensitive to packet loss but typically are sensitive to delays. UDP, then, is a faster protocol because packet delivery is not guaranteed. RTP is often used with VoIP. VoIP data packets live in RTP packets, which are inside UDP-IP packets.
The data part supports applications with real-time properties such as continuous media (such as audio and video), including timing reconstruction, loss detection, security, and content identification.
The control part (RTCP) supports real-time conferencing of groups of any size within the internet.
is the Internet-standard protocol for the transport of real-time data, including audio and video. RTP can use either TCP or UDP as a transport mechanism. However, UDP is used more
often because applications using RTP are less sensitive to packet loss but typically are sensitive to delays. UDP, then, is a faster protocol because packet delivery is not guaranteed. RTP is often used with VoIP. VoIP data packets live in RTP packets, which are inside UDP-IP packets.
The data part supports applications with real-time properties such as continuous media (such as audio and video), including timing reconstruction, loss detection, security, and content identification.
The control part (RTCP) supports real-time conferencing of groups of any size within the internet.
DHCP
Dynamic Host Configuration Protocol (DHCP),
enables ranges of IP addresses, known as scopes, to be defined on a system running a DHCP server application. When another system configured as a DHCP client is initialized, it asks the server for an address. If all things are as:
they should be, the server assigns an address from the scope to the client for a predetermined amount of time, known as the lease.
In addition to an IP address and the subnet mask, the DHCP server can supply many other pieces of information; although, exactly what can be provided depends on the DHCP server implementation. In addition to the address information, the default gateway is often supplied, along with DNS
information.
DHCP lease
lease is the length of time the client can have the assigned IP address.
At various points during the lease (normally the 50 percent and 85 percent points), the client attempts to renew the lease from the server. If the server cannot perform a renewal, the lease expires at 100 percent, and the client stops using the address.
At various points during the lease (normally the 50 percent and 85 percent points), the client attempts to renew the lease from the server. If the server cannot perform a renewal, the lease expires at 100 percent, and the client stops using the address.
DHCP Scope
The range of IP address available to assign to clients.
DHCP Reservation
In addition to having DHCP supply a random address from the scope, you can configure it to supply a specific address to a client. Such an arrangement is known as a reservation. Reservations are a means by which you can still use DHCP for a system but at the same time guarantee that it always has the same IP address. DHCP can also be configured for exclusions. In this scenario, certain IP addresses are not given out to client systems.
DHCP Process
1. DHCPDISCOVER packet: a client sends a broadcast looking for a server.
2. DHCPOFFER packet: Server sends an address
3.DHCPREQUEST packet: The client then asks to have the offered address.
4. DHCPACK packet: server assigns the address and sends an acknowledgment to the requesting client.
These communications are done as broadcast.
2. DHCPOFFER packet: Server sends an address
3.DHCPREQUEST packet: The client then asks to have the offered address.
4. DHCPACK packet: server assigns the address and sends an acknowledgment to the requesting client.
These communications are done as broadcast.
DHCP advantages
First, administrators do not need to manually configure each system. Second, human error such as the assignment of duplicate IP addresses is eliminated. Third, DHCP removes the need to reconfigure systems if they move from one subnet to another, or if you decide to make a wholesale change in the IP addressing structure.
DHCP disadvantages
DHCP traffic is broadcast-based and thus generates network
traffic—albeit a small amount. Finally, the DHCP server software must be installed and configured on a server, which can place additional processor load (again, minimal) on that system.
traffic—albeit a small amount. Finally, the DHCP server software must be installed and configured on a server, which can place additional processor load (again, minimal) on that system.
SNMP
Simple Network Management Protocol
Provides network devices with a method to monitor and control network devices; manage configurations, statistics
collection, performance, and security; and report network management information to a management console.
Both SNMPv1 and v2 are not secured.
SNMPv3 An enhanced SNMP service offering both encryption and authentication services.
Provides network devices with a method to monitor and control network devices; manage configurations, statistics
collection, performance, and security; and report network management information to a management console.
Both SNMPv1 and v2 are not secured.
SNMPv3 An enhanced SNMP service offering both encryption and authentication services.
SNMP agent
A software component that enables a device to communicate
with, and be contacted by, an SNMP management system.
with, and be contacted by, an SNMP management system.
SNMP trap
An SNMP utility that sends an alarm to notify the administrator
that something within the network activity differs from the
established threshold, as defined by the administrator.
that something within the network activity differs from the
established threshold, as defined by the administrator.
NMS (Network Management System)
An application that acts as a central management point for network management. Most NMS systems use SNMP to communicate with network devices.
MIB
Management Information Base
A data set that defines the criteria that can be retrieved and set on a device using SNMP
A data set that defines the criteria that can be retrieved and set on a device using SNMP
SNMP Communities
SNMP communities are logical groupings of systems. When a system is configured as part of a community, it communicates only with other devices that have the same community name. In addition, it accepts Get, Get Next, or Set commands only from an SNMP manager with a community name it recognizes.
Internet IP Address
Types, Features, and Classes of IP Address
The IP address is a familiar term for most computer users. An IP address is the unique numerical address of a device in a computer network that uses Internet Protocol for communication. The IP address allows you to pinpoint a particular device from the billions of devices on the Internet. To send you a letter, someone needs your mailing address. In the same sense, one computer needs the IP address of another computer to communicate with it.
An IP address consists of four numbers; each can contain one to three digits. These numbers are separated with a single dot (.). These four numbers can range from 0 to 255.
Types of IP addresses
The IP addresses can be classified into two. They are listed below.
1) Static IP addresses
2) Dynamic IP addresses
Static IP Addresses
As the name indicates, the static IP addresses usually never change but they may be changed as a result of network administration. They serve as a permanent Internet address and provide a simple and reliable way for communication. From the static IP address of a system, we can get many details such as the continent, country, region and city in which a computer is located, The Internet Service Provider (ISP) that serves that particular computer and non-technical information such as precise latitude and longitude of the country, and the locale of the computer. There are many websites providing IP address lookups. You can find out your IP addresses at http://whatismyip.org/.
Dynamic IP Addresses
Dynamic IP address are the second category. These are temporary IP addresses. These IP addresses are assigned to a computer when they get connected to the Internet each time. They are actually borrowed from a pool of IP addresses, shared over various computers. Since a limited number of static IP addresses are available, ISPs usually reserve the portion of their assigned addresses for sharing among their subscribers in this way.
Static IP addresses are considered as less secure than dynamic IP addresses because they are easier to track.
IP Version 4 and IP Version 6
The two versions of IP addresses currently running are IP versions 4 (IPv4) and IP versions 6 (IPv6). There are many features with these two versions.
IP Version 6
The IPv6 is the most recent version of Internet Protocol. As the Internet is growing rapidly, there is a global shortage for IPv4. IPv6 was developed by the Internet Engineering Task Force (IETF). IPv6 is intended to replace the IPv4. IPv6 uses a 128-bit address and it allows 2128 i.e. approximately 3.4×1038 addresses. The actual number is slightly smaller as some ranges are reserved for special use or not used. The IPv6 addresses are represented by 8 groups of four hexadecimal digits with the groups being supported by colons. An example is given below:
Eg: 2001:0db8:0000:0042:0000:8a2e:0370:7334
The features of IPv6
The main features of the IPv6 are listed below.
1) IPv6 provides better end-to-end connectivity than IPv4.
2) Comparatively faster routing.
3) IPv6 offers ease of administration than IPv4.
4) More security for applications and networks.
5) It provides better Multicast and Anycast abilities.
6) Better mobility features than IPv4.
7) IPv6 follows the key design principles of IPv4 and so that the transition from IPv4 to IPv6 is smoother.
These are the key features of the IPv6 when compared to the IPv4. However, IPv6 has not become popular as IPv4.
IP Version 4
IP Version 4 (IPv4) was defined in 1981. It has not undergone much changes from that time. Unfortunately, there is a need of IP addresses more than IPv4 could supply.
IPv4 uses 32-bit IP address. So the maximum number of IP address is 232—or 4,294,967,296.
This is a little more than four billion IP addresses. An IPv4 address is typically formatted as four 8-bit fields. Each 8-bit field represents a byte of the IPv4 address. As we have seen earlier, each fields will be separated with dots. This method of representing the byte of an IPv4 address is referred to as the dotted-decimal format. The bytes of the IPv4 is further classified into two parts. The network part and the host part.
Network Part
This part specifies the unique number assigned to your network. It also identifies the class of network assigned. The network part takes two bytes of the IPv4 address.
Host Part
This is the part of the IPv4 address that you can assign to each host. It uniquely identifies this machine on your network. For all hosts on your network, the network part of the IP address will be the same and host part will be changing.
IP address and classes
The IP hierarchy contains many classes of the IP addresses. Broadly, the IPv4 addressing system is divided into five classes of IP address. All the five classes are identified by the first octet of the IP address.
The classes of IPv4 addresses
The different classes of the IPv4 address are the following:
1) Class A address
2) Class B address
3) Class C address
4) Class D address
5) Class E address
Class A Address
The first bit of the first octet is always set to zero. So that the first octet ranges from 1 – 127. The class A address only include IP starting from 1.x.x.x to 126.x.x.x. The IP range 127.x.x.x is reserved for loop back IP addresses. The default subnet mask for class A IP address is 255.0.0.0. This means it can have 126 networks (27-2) and 16777214 hosts (224-2). Class A IP address format is thus: 0NNNNNNN.HHHHHHHH.HHHHHHHH.HHHHHHHH.
Class B Address
Here the first two bits in the first two bits is set to zero. Class B IP Addresses range from 128.0.x.x to 191.255.x.x. The default subnet mask for Class B is 255.255.x.x. Class B has 16384 (214) Network addresses and 65534 (216-2) Host addresses. Class B IP address format is: 10NNNNNN.NNNNNNNN.HHHHHHHH.HHHHHHHH
Class C Address
The first octet of this class has its first 3 bits set to 110. Class C IP addresses range from 192.0.0.x to 223.255.255.x. The default subnet mask for Class C is 255.255.255.x. Class C gives 2097152 (221) Network addresses and 254 (28-2) Host addresses. Class C IP address format is: 110NNNNN.NNNNNNNN.NNNNNNNN.HHHHHHHH
Class D Address
The first four bits of the first octet in class D IP address are set to 1110. Class D has IP address rage from 224.0.0.0 to 239.255.255.255. Class D is reserved for Multicasting. In multicasting data is not intended for a particular host, but multiple ones. That is why there is no need to extract host address from the class D IP addresses. The Class D does not have any subnet mask.
Class E Address
The class E IP addresses are reserved for experimental purpose only for R&D or study. IP addresses in the class E ranges from 240.0.0.0 to 255.255.255.254. This class too is not equipped with any subnet mask.
Types:-
The IP addresses are divided into three different types, based on their operational characteristics:
1. unicast IP addresses – an address of a single interface. The IP addresses of this type are used for one-to-one communication. Unicast IP addresses are used to direct packets to a specific host. Here is an example:
In the picture above you can see that the host wants to communicate with the server. It uses the IP address of the server (192.168.0.150) to do so.
2. multicast IP addresses – used for one-to-many communication. Multicast messages are sent to IP multicast group addresses. Routers forward copies of the packet out to every interface that has hosts subscribed to that group address. Only the hosts that need to receive the message will process the packets. All other hosts on the LAN will discard them. Here is an example:
R1 has sent a multicast packet destined for 224.0.0.9. This is an RIPv2 packet and only routers on the network should read it. R2 will receive the packet and read it. All other hosts on the LAN will discard the packet.
3. broadcast IP addresses – used to send data to all possible destinations in the broadcast domain (the one-to-everybody communication). The broadcast address for a network has all host bits on. For example, for the network 192.168.30.0 255.255.255.0 the broadcast address would be 192.168.0.255. Also, the IP address of all 1’s (255.255.255.255) can be used for local broadcast. Here’s an example:
R1 has sent a broadcast packet to the broadcast IP address 192.168.30.255. All hosts in the same broadcast domain will receive and process the packet.
No comments:
Post a Comment