What is TCP/IP PROTOCOL SUITE ?
The TCPIIP protocol suite was developed prior to the OSI model. Therefore, the layers in the TCP/IP protocol suite do not exactly match those in the OSI model. The original TCP/IP protocol suite was defined as having four layers: host-to-network, internet, transport, and application. However, when TCP/IP is compared to OSI, we can say that the host-to-network layer is equivalent to the combination of the physical and data link layers. The internet layer is equivalent to the network layer, and the application layer is roughly doing the job of the session, presentation, and application layers with the transport layer in TCPIIP taking care of part of the duties of the session layer. So in this book, we assume that the TCPIIP protocol suite is made of five layers: physical, data link, network, transport, and application. The first four layers provide physical standards, network interfaces, internetworking, and transport functions that correspond to the first four layers of the OSI model. The three topmost layers in the OSI model, however, are represented in TCPIIP by a single layer called the application layer (see Figure ).
TCP/IP is a hierarchical protocol made up of interactive modules, each of which provides a specific functionality; however, the modules are not necessarily interdependent. Whereas the OSI model specifies which functions belong to each of its layers, the layers of the TCP/IP protocol suite contain relatively independent protocols that can be mixed and matched depending on the needs of the system. The term hierarchical means that each upper-level protocol is supported by one or more lower-level protocols.
At the transport layer, TCP/IP defines three protocols: Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and Stream Control Transmission Protocol (SCTP). At the network layer, the main protocol defined by TCP/IP is the Internetworking Protocol (IP); there are also some other protocols that support data movement in this layer.
protocols. It is an unreliable and connectionless protocol-a best-effort delivery service.
The term best effort means that IP provides no error checking or tracking. IP assumes
the unreliability of the underlying layers and does its best to get a transmission through
to its destination, but with no guarantees.
IP transports data in packets called datagrams, each of which is transported separately.
Datagrams can travel along different routes and can arrive out of sequence or be
duplicated. IP does not keep track of the routes and has no facility for reordering datagrams
once they arrive at their destination.
The limited functionality of IP should not be considered a weakness, however. IP
provides bare-bones transmission functions that free the user to add only those facilities
necessary for a given application and thereby allows for maximum efficiency.
physical address. On a typical physical network, such as a LAN, each device on a link
is identified by a physical or station address, usually imprinted on the network interface
card (NIC). ARP is used to find the physical address of the node when its Internet
address is known. ARP..
address when it knows only its physical address. It is used when a computer is connected
to a network for the first time or when a diskless computer is booted.
gateways to send notification of datagram problems back to the sender. ICMP sends
query and error reporting messages.
transmission of a message to a group of recipients.
UDP. IP is a host-to-host protocol, meaning that it can deliver a packet from one
physical device to another. UDP and TCP are transport level protocols responsible
for delivery of a message from a process (running program) to another process. A new
transport layer protocol, SCTP, has been devised to meet the needs of some newer
applications.
protocols. It is a process-to-process protocol that adds only port addresses, checksum
error control, and length information to the data from the upper layer. UDP
applications. TCP is a reliable stream transport protocol. The term stream, in this context,
means connection-oriented: A connection must be established between both ends
of a transmission before either can transmit data.
At the sending end of each transmission, TCP divides a stream of data into smaller
units called segments. Each segment includes a sequence number for reordering after
receipt, together with an acknowledgment number for the segments received. Segments
are carried across the internet inside of IP datagrams. At the receiving end, TCP collects
each datagram as it comes in and reorders the transmission based on sequence
numbers. TCP..
applications such as voice over the Internet. It is a transport layer protocol that combines
the best features of UDP and TCP..
and application layers in the OSI modeL Many protocols are defined at this layer..
At the transport layer, TCP/IP defines three protocols: Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and Stream Control Transmission Protocol (SCTP). At the network layer, the main protocol defined by TCP/IP is the Internetworking Protocol (IP); there are also some other protocols that support data movement in this layer.
Physical and Data Link Layers
At the physical and data link layers, TCPIIP does not define any specific protocol. It supports all the standard and proprietary protocols. A network in a TCPIIP internetwork can be a local-area network or a wide-area network.Network Layer
At the network layer (or, more accurately, the internetwork layer), TCP/IP supports the Internetworking Protocol. IP, in turn, uses four supporting protocols: ARP, RARP, ICMP, and IGMP.Internetworking Protocol (IP)
The Internetworking Protocol (IP) is the transmission mechanism used by the TCP/IPprotocols. It is an unreliable and connectionless protocol-a best-effort delivery service.
The term best effort means that IP provides no error checking or tracking. IP assumes
the unreliability of the underlying layers and does its best to get a transmission through
to its destination, but with no guarantees.
IP transports data in packets called datagrams, each of which is transported separately.
Datagrams can travel along different routes and can arrive out of sequence or be
duplicated. IP does not keep track of the routes and has no facility for reordering datagrams
once they arrive at their destination.
The limited functionality of IP should not be considered a weakness, however. IP
provides bare-bones transmission functions that free the user to add only those facilities
necessary for a given application and thereby allows for maximum efficiency.
Address Resolution Protocol
The Address Resolution Protocol (ARP) is used to associate a logical address with aphysical address. On a typical physical network, such as a LAN, each device on a link
is identified by a physical or station address, usually imprinted on the network interface
card (NIC). ARP is used to find the physical address of the node when its Internet
address is known. ARP..
Reverse Address Resolution Protocol
The Reverse Address Resolution Protocol (RARP) allows a host to discover its Internetaddress when it knows only its physical address. It is used when a computer is connected
to a network for the first time or when a diskless computer is booted.
Internet Control Message Protocol
The Internet Control Message Protocol (ICMP) is a mechanism used by hosts andgateways to send notification of datagram problems back to the sender. ICMP sends
query and error reporting messages.
Internet Group Message Protocol
The Internet Group Message Protocol (IGMP) is used to facilitate the simultaneoustransmission of a message to a group of recipients.
Transport Layer
Traditionally the transport layer was represented in TCP/IP by two protocols: TCP andUDP. IP is a host-to-host protocol, meaning that it can deliver a packet from one
physical device to another. UDP and TCP are transport level protocols responsible
for delivery of a message from a process (running program) to another process. A new
transport layer protocol, SCTP, has been devised to meet the needs of some newer
applications.
User Datagram Protocol
The User Datagram Protocol (UDP) is the simpler of the two standard TCPIIP transportprotocols. It is a process-to-process protocol that adds only port addresses, checksum
error control, and length information to the data from the upper layer. UDP
Transmission Control Protocol
The Transmission Control Protocol (TCP) provides full transport-layer services toapplications. TCP is a reliable stream transport protocol. The term stream, in this context,
means connection-oriented: A connection must be established between both ends
of a transmission before either can transmit data.
At the sending end of each transmission, TCP divides a stream of data into smaller
units called segments. Each segment includes a sequence number for reordering after
receipt, together with an acknowledgment number for the segments received. Segments
are carried across the internet inside of IP datagrams. At the receiving end, TCP collects
each datagram as it comes in and reorders the transmission based on sequence
numbers. TCP..
Stream Control Transmission Protocol
The Stream Control Transmission Protocol (SCTP) provides support for newerapplications such as voice over the Internet. It is a transport layer protocol that combines
the best features of UDP and TCP..
Application Layer
The application layer in TCPIIP is equivalent to the combined session, presentation,and application layers in the OSI modeL Many protocols are defined at this layer..
What is TCP/IP PROTOCOL SUITE ?
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