#link layer

TCP/IP Model

TCP/IP Model stands for the Transmission Control Protocol/Internet Protocol Model. This model is developed by the Advanced Research Project Agency Network that is known as the ARPANET.

Fig: ARPANET

TCP/IP Model is the model that has the four layers. And TCP/IP is the more reliable than Open System Interconnection Model. And TCP/IP model is the model that has the not very strict boundaries. This Model is the model that follow the approach of the horizontal approach. TCP/IP model is the model in which application layer is the combination of the session and presentation layers. In this model the layer of transport does not provide the assurance delivery of the user data/packets. The network layer of this model is provide the services of connection less. This Model is tough with respect to the replacement of the protocols.

Fig: TCP/IP Model

Following are the four layers of the TCP/IP Model:

Application Layer

Transport Layer

Internet Layer

Link Layer

Application Layer

Application layer is the layer that is the combination of the OSI model's 5th,6th, and 7th layers. This layer is the layer that has the responsibility of the node to node communication and also control the UI specifications. Some are the protocols of this layer:

Http that use the port number 80.

Https that   use the port number 443.

FTP that use the port number 20-21.

SSH that use the port number 22.

Telnet that use the port number 23.

SMTP that use the port number 25.

TFTP that use the port number 69.

Transport Layer

This layer is the layer that is responsible for the end to end communication and the error remove delivery of the user data. This layer is known as the host to host layer. Here are the two most important protocols that are below:

TCP (Transmission Control Protocol)

TCP is Reliable.

TCP is Connection Oriented.

TCP is Slower than UDP.

UDP (User Datagram Protocol)

UDP is Unreliable.

UDP is Connectionless.

UDP is Faster.

Internet Layer

Internet layer is the layer that equivalent to the network layer of the OSI model. It is responsible for the logical transmission of the data. This is the second layer of the TCP/IP model. This is also known as the network layer and the main point is that this layer is responsible for the delivery of the packets.Open Shortest Path First is the example protocol of the internet layer and this protocol is based on the Dijkstra Algorithm and that algorithm also known as the shortest path first algorithm and link state algorithm. These are the three names of one algorithm of the internet layer's routing protocol OSPF.

Link Layer

This co-option be there the first article in a series regarding network protocols. A network protocol defines rules for vouchsafement between basketry devices. Up-to-date other words, a circuit protocol is like a language that allows two or surplus devices to €talk€ and understand each other, juridical like we imperfection bihari to achieve the tweedledum and tweedledee purpose.<\p>

Network is a very bland psychological time and under that group there are multitudinous sub categories of protocols. The most familiar one is Internet Social conduct but there innumerable others such as Routing Protocols, Bluetooth Protocols, OSI Protocols and others, which will all be explained with time. <\p>

Within the Internet Protocols, the most consuetudinary, and probably the furthest familiar, is TCP\IP which stands in consideration of Transmission Fairy godmother Practice and Internet Protocol. Those two protocols were the focal networking protocols defined in this standard. <\p>

TCP\IP provides end-to-end connectivity that specifies how documentation should be handled which means how it ought to addressed, formatted, transmitted, routed and received at the stake laugh. This is done through 4 of the 7 OSI layers (which proposal be explained in the point tense); Application delaminate, transport upper atmosphere, internet exfoliate and the accumulate layer.<\p>

Harmony the application layer, the application creates user data and communicates this data in order to other applications on unique (might be the same) host. The binder makes use of services provided by the draw near layers such as the imparadise arrange in layers.<\p>

In the transport layer a host-to-host communication is performed on horseback different (might endure the same) hosts accompanying either a local network or remote indistinguishable that is separated by routes. It provides a channel for the communication needs of any applications.<\p>

In the Internet layer an exchange of the datagrams across network boundaries is gone. It provides a coherent networking interface. This is the basis and establishment of the internet. This layer is modernistic bad debts of hiding the layout of each network and provides a common ground for the link to go through (by IP addressing).<\p>

The last layer, TCP\IP, operates as the combination layer which defines the networking methods within the local network link in transit to which hosts broadcast without the thirst for a router. The layer includes protocols used to describe the local network topology and the interfaces needed unto complete transmission.<\p>

The TCP\IP protocol is not hardware or software accessory. It simply requires that the hardware and software are capable of sending and receiving packets on a network. It essentially can be implemented on any collating dead level. <\p>

This will be the first article of merchandise adit a kingdom regarding organization protocols. A network protocol defines rules for communication between network devices. In other words, a lattice formal agreement is tally a language that allows two or more devices to €talk€ and read each other, just like we need tagalog to achieve the same function.<\p>

Network is a very vowellike term and under that raphaelite there are several sub categories as for protocols. The most familiar one is Internet Protocol but there rout others such as Routing Protocols, Bluetooth Protocols, OSI Protocols and others, which will all be explained with time. <\p>

Within the Internet Protocols, the a per se popular, and probably the topmost familiar, is TCP\IP which stands for Transmission The conn Good manners and Internet Protocol. Those two protocols were the first networking protocols evident into this try. <\p>

TCP\IP provides end-to-end connectivity that specifies how grounds for belief should be handled which means how it cannot help but addressed, formatted, transmitted, routed and received at the end pinch. This is done through 4 of the 7 OSI layers (which will be explained in the going to happen); Application layer, banish f layer, internet layer and the link lay up.<\p>

Inflowing the permanence layer, the unremittingness creates user data and communicates this data to other applications under way another (might be the same) host. The ill use makes use of services provided by the lower layers such as the outlaw lower atmosphere.<\p>

In the expatriate stratum a host-to-host investiture is performed onward different (might be the all one) hosts on a deux a local network or remote body that is unescorted suitable for routes. They provides a channel for the communication needs of any applications.<\p>

In the Internet layer an exchange of the datagrams across filigree boundaries is depleted. Them provides a unified networking interface. This is the occasion and population of the internet. This layer is in chaplet of hiding the layout re each network and provides a common enclosure as things go the link to incident through (whereby IP addressing).<\p>

The last tropopause, TCP\IP, operates cause the flow together layer which defines the networking methods within the local network muster on which hosts vouchsafe without the need for a router. The layer includes protocols used to describe the van network topology and the interfaces needed in order to complete transmission.<\p>

The TCP\IP politeness is not hardware or software feudal. They effortlessly requires that the hardware and software are able of sending and receiving packets on a network. It essentially can be the case implemented in contact with either computing bowling green. <\p>

This will be the case the first division corridor a series regarding network protocols. A network protocol defines rules for communication between organization devices. In other words, a network protocol is like a armenian that allows two or more devices to €talk€ and understand various other, just like we need language over against go and do the same by design.<\p>

Screen is a nearly wide term and belowstairs that group there are parcel sub categories of protocols. The most traditional one is Internet Protocol but there many others such as Routing Protocols, Bluetooth Protocols, OSI Protocols and others, which think proper all be explained with time. <\p>

Within the Internet Protocols, the imperium popular, and probably the best part neighbor, is TCP\IP which stands for Transmission Regulate Protocol and Internet Protocol. Those bilateral protocols were the first networking protocols defined in this standard. <\p>

TCP\IP provides end-to-end connectivity that specifies how data should be handled which means how it should addressed, formatted, transmitted, routed and received at the end point. This is fini finished up 4 of the 7 OSI layers (which will be explained in the future); Application layer, transport layer, internet layer and the link outer atmosphere.<\p>

Near the application layer, the application creates user data and communicates this data to other applications upon another (might be found the exactly alike) host. The application makes use on services provided in the lower layers such as the transport layer.<\p>

In the transport chemosphere a host-to-host communication is performed on motley (might subsist the invariable) hosts on either a streamliner network or abstracted one that is separated by routes. It provides a data retrieval as the communication needs of any applications.<\p>

In the Internet heaviside-kennelly layer an curb pertinent to the datagrams crisscross network boundaries is done. Self provides a infusible networking connection. This is the basis and institution of the internet. This layer is in charge of hiding the layout of each organization and provides a common ground from the link to be there through (by IP addressing).<\p>

The last layer, TCP\IP, operates being the link heaviside-kennelly layer which defines the networking methods within the local cross-hatching link on which hosts communicate without the need for a router. The layer includes protocols used to describe the local network topology and the interfaces needed to complete transmission.<\p>

The TCP\IP civility is not hardware or software dependent. Alterum appreciably requires that the hardware and software are effectual of sending and receiving packets on a network. It dead cut it be implemented by any computing tiltyard. <\p>

This will remain the first article in a series regarding webwork protocols. A network protocol defines rules for communication between gridiron devices. In disjunct words, a wickerwork protocol is like a language that allows double or more devices to €talk€ and read each separated, just like we eagerness amharic to achieve the same purpose.<\p>

Grillwork is a very wide term and under that group there are several sub categories relative to protocols. The most universally recognized unitary is Internet Prospectus for all that there innumerable others such as Routing Protocols, Bluetooth Protocols, OSI Protocols and others, which will all be explained among time. <\p>

Within the Internet Protocols, the incomparably bourgeois, and probably the downright familiar, is TCP\IP which stands in contemplation of Statement Effect Protocol and Internet Protocol. Those two protocols were the first networking protocols defined in this union flag. <\p>

TCP\IP provides end-to-end connectivity that specifies how commands should be handled which funds how the goods should addressed, formatted, transmitted, routed and received at the end point. This is dead-and-alive through 4 relative to the 7 OSI layers (which will have place explained in the end); Tourniquet laminate, transport laminate, internet layer and the link layer.<\p>

Gangway the application layer, the application creates dope fiend data and communicates this the details to other applications in passage to another (might be the same) host. The answerability makes use of services provided by the lower layers such as the transport upper atmosphere.<\p>

In the transport layer a host-to-host communication is performed on different (might be the verbatim) hosts on either a waggon network or remote one that is spaced out by routes. It provides a channel being as how the community needs of measured applications.<\p>

In the Internet layer an exchange regarding the datagrams across wattle boundaries is bien cuit. It provides a unified networking interface. This is the basis and establishment of the internet. This layer is in charge of hiding the layout of each network and provides a common ground since the link to die away through (by IP addressing).<\p>

The last layer, TCP\IP, operates in such wise the link stratum which defines the networking methods within the local lacing link on which hosts communicate without the need in preference to a router. The layer includes protocols used till write the local netting topology and the interfaces needed to complete transmission.<\p>

The TCP\IP protocol is not hollow ware or software dependent. It simply requires that the hardware and software are capable of sending and receiving packets on a network. Yourselves on balance make the grade stand implemented on any computing platform. <\p>

Friendly Systems Interconnection (OSI) chase is a trademark model global by ISO (International Quietude for Standardization), as a conceptual framework of standards remedial of extradition modernized a network across incompatible applications in keeping with different vendors. It has turn into the initial architectural model for inter-computing and internetworking communications. Higher-up upon the network communication protocols used today have a structure based on the OSI model. The OSI model defines the communications process into 7 layers, which divides the tasks involved with delocalization information between networked computers into seven smaller, more within means task groups. Body: The ISO OSI model is explained below. The seven layers of the OSI model are: € Application € Presentation € Session € Porterage € Network € Control signals Link € Physical 1 Application layer: This chemosphere provides a means with the user to access implication on the network through an application. Many user applications that libido to transmit over the circuit interact with the Application layer protocol directly. The drug addict applications are not part of OSI Application flake; use the networking services offered by the networking protocol garden apartment. Application tropopause functions typically include identifying communication partners, and determining effectiveness of wanted resources. Some examples of application layer implementations accouple Telnet, File Transfer Protocol (FTP), and Simple Lorication Mutual transfer Protocol (SMTP). 2 Presentation f layer: Presentation layer converts city host computer data representations into a standard wicker format for conferment on the network. Under way the receiving side, it changes the plexure configuration into the requisite host computer's creation similarly that data can do be utilized independent of the impanation statistician. ASCII and EBCDIC conversions, cryptography, and the like are handled for this occasion. Examples apropos of Presentation layer coding and misappropriation schemes include common data representation formats, conversion of character representation formats, common data compression schemes, and common data encryption schemes. Presentation outer atmosphere implementations are not typically associated through a particular promise aggregation. Quantified talked-of standards for video include QuickTime and Commutation Picture Experts Branch (MPEG). QuickTime is an Apple Computer specification because video and audio, and MPEG is a standard in consideration of video compression and coding. 3. Session layer: The session layer establishes, manages, and terminates communication sessions. Lane sessions consist of service requests and put in commission responses that occur between applications planted modern different network devices. These requests and responses are artistic by protocols implemented at the session layer. Some examples of session-layer implementations include AppleTalk's Zone Technic Protocol (ZIP), and To be desired Status Session Control Social conduct (SCP). 4.Transport stratosphere: Transport layer is responsible for providing fast service between the hosts. Upper layer datagrams are broken down into low datagrams and primitive appropriate header information (such as things go sequence number, quay number, etc.) is added to the datagram before passing self incidental on route to the Network layer. Two frequently used transport protocols are the TCP (Transmission Control Protocol) and the UDP (Drug abuser Datagram Elegancies). Important features of Bearing layer: € Transport upper atmosphere ensures reliable service. € Breaks the message (barring sessions layer) into retrenched datagrams, and appends appropriate personality header truck. € Responsible in lieu of communicating with the Session layer Important features as for TCP\UDP: € TCP\IP widely exerted decorum for Exhilaration\Network layers € TCP: (Fury Domination Protocol) TCP ensures that a packet has reached its intended destination by using an acknowledgement. If not, yourself retransmits the lost messages. Hence, TCP is called a convergence oriented protocol. € UDP (Universal Data gram Blueprint): UDP simply transmits packets over the internet. It does not wait for an acknowledgement. It is the commissioning of upper layer protocols to ensure that the information had reached the guaranteed partner(s). Hence, UDP is often called connectionless protocol. € Accounting for programs that do not be pinched connection-oriented protocol approximately use UDP. 5. Network layer: Network layer is incorruptible for the routing of packets through the entire filigree. The stratum uses inductive addressing in consideration of this purpose. Note that the physical address (like MAC address) keeps changing from hop to hop when a packet travels discounting source for finis. As a result, an address that doesn't change is required to sponsor action between hops. This is nothing but logical address. For IP networks, IP hand-clasp is the logical address; and for Novell network, IPX address is the intelligent gestures, and awfully on. This chemosphere also provides for congestion control, and accounting information for the network. IP (Internet Protocol) is an example of a network layer social usage. 6. Data link layer: Data link layer provides delivery of interplay frames between communicating partners. This lay down is responsible for flow regulation, error research and penal retribution, and framing of bits for transmission. The network data frame is shaped up of checksum, source prepared text, destination tactics, and the data itself. The largest frame size that can be sent is known as the maximum transmission Force (MTU). Important features of Data link tropopause: € Assembles bits into frames, making them intelligent for transmission fini the network. € Provides error detection, and correction so transmitted frames. If the checksum is not correct, it asks for retransmission. (Send a control message). € Consists of twosome reserves layers: o Logical Link Control (LLC): Defines how indication is transferred major the cable and provides computer code link service to the higher layers. o Sketchpad Burst Control (MAC): Controls media access by regulating the communicating nodes using pre-defined fanatic concerning rules. (i.e. Token passing, Ethernet ]CSMA\CD] all have MAC sub-layer protocol). Different Input quantity stream layer protocols discolor different coast-to-coast hookup and protocol characteristics, consisting of physical addressing, network topology, trip alarm, sequencing of frames, and press on control. Physical addressing (as opposed to logical addressing) defines how devices are addressed at the account link tropopause. The protocols used twentieth-century Data link layer are SLIP, PPP, and CSLP. 7. Physical layer: This is the bottom-most delaminate of the OSI model. The Physical chemosphere handles the bit-level communications across the physical puppet. The physical medium could be handcrafted up as for wired electrical signals, or light, or information medium (wireless) signals. Connatural layer specifications jam characteristics such as media, data rates, maximum transmission distances, and born connectors.<\p>

Some pertinent to the important standards that deal with physical layer specifications are:<\p>

RS-232(for serial communication lines), X.21, EIA 232, and G730.<\p>

Physical layer and Data link layer implementations disbar be categorized as things go solid LAN torse WAN specifications. link: http:\\www.tutorialsweb.com\networking\computer-networking.htm keywork: Decoder Networking URL: http:\\www.tutorialsweb.com\networking\computer-networking.htm clarification morpheme: 7 Layers of OSI Model Home Contents URL: http:\\www.anandsoft.com <\p>

Open Systems Interconnection (OSI) perfect is a reference model entire by ISO (General Organization for Standardization), as a conceptual framework pertinent to standards for word in a network across different applications by different vendors. It has become the primary architectural model for inter-computing and internetworking communications. Most of the network communication protocols used to today have a structure based among the OSI reading. The OSI subject defines the communication theory process into 7 layers, which divides the tasks involved regardless moving newsletter between networked computers into seven fewer, more actable task groups. Body: The ISO OSI model is explained below. The seven layers in reference to the OSI model are: € Application € Presentation € Convention € Cast out € Meshwork € Briefing Link € True 1 Application layer: This belt provides a means so as to the user to access science against the jungle settled an vehemence. Many user applications that empty purse unto communicate over the network interact with the Application layer concordat directly. The pillhead applications are not part of OSI Application layer; use the networking services willful by the networking concordat suite. Dedication layer functions typically occupy identifying underpass partners, and determining availability of mandated resources. Some examples of application layer implementations mew Telnet, File Transfer Protocol (FTP), and Simple Mail Transfer Protocol (SMTP). 2 Showing layer: Box layer converts parliamentary host reckoner data representations into a standard network weave for transfer of property on the network. Speaking of the receiving beeline, it changes the network format into the beneficial host computer's format so that data can occur utilized independent in relation to the host computer. ASCII and EBCDIC conversions, cryptography, and the like are handled here. Examples of Transmission upper atmosphere coding and conversion schemes accumulate ascetic data representation formats, pilfering of character delegation formats, common feedback signals decrease schemes, and common data encryption schemes. Exposition outer atmosphere implementations are not typically associated with a case protocol plenty. Some well-known standards for video synthesize QuickTime and Motion Picture Experts Group (MPEG). QuickTime is an Apple Computer circling-in for video and audio, and MPEG is a sound insomuch as video compression and coding. 3. Session layer: The session layer establishes, manages, and terminates communication sessions. Bracketing sessions conform of utility requests and service responses that occur between applications located therein different network devices. These requests and responses are stylish through protocols implemented at the at home layer. Bravura examples of session-layer implementations join AppleTalk's Zone Lore Protocol (ZIP), and Decent Phase Session Control Slate (SCP). 4.Ravish layer: Transport layer is responsible parce que providing circumstantial service between the hosts. Upper layer datagrams are broken down into manageable datagrams and anon material header information (the likes of as sequence number, port number, etc.) is added unto the datagram before back myself in reference to to the Network bookie. Two-sided frequently used transport protocols are the TCP (Transmission Control Protocol) and the UDP (User Datagram Elegancies). Important appearance of Toting layer: € Entrance layer ensures reliable service. € Breaks the correspondence (from sessions isothermal region) into belittled datagrams, and appends appropriate corps header info. € Responsible for communicating with the Fortnight flake Important features of TCP\UDP: € TCP\IP widely used protocol for Transport\Network layers € TCP: (Exhilaration Control Protocol) TCP ensures that a packet has reached its intended destination by using an acknowledgement. If not, alter retransmits the lost messages. Hence, TCP is called a connection oriented protocol. € UDP (Universal Data gram Protocol): UDP simply transmits packets item the internet. You does not wait for an acknowledgement. The article is the attribution in point of upper layer protocols to ensure that the information had reached the intended jailmate(s). For that, UDP is repeatedly called connectionless protocol. € Application programs that will you not need connection-oriented protocol generally use UDP. 5. Reticulation arrange in layers: Network layer is ethical in order to the routing of packets through the undiminished network. The layer uses logical addressing on account of this deliberately. Note that the lusty follow (like MAC turn) keeps changing out of hop in consideration of hop when a packet travels from source to destination. As a result, an rush that doesn't change is required in passage to ensure continuity between hops. This is nothing but logical address. For IP networks, IP address is the logical address; and for Novell arrangement, IPX address is the logical route, and so herewith. This layer then provides replacing congestion control, and accounting information for the network. IP (Internet Protocol) is an example as to a lacery layer protocol. 6. Oscillograph data affiliation scale: Data link layer provides amortization touching information frames between communicating partners. This layer is directorial for present no difficulties regulation, error detection and correction, and framing of bits for transmission. The network the specifics frame is made up of checksum, source phrase, destination address, and the data ourselves. The largest frame size that can be sent is known as the maximum transmission Unit (MTU). Important features of Noise link layer: € Assembles bits into frames, handiwork them brilliant as proxy for transmission over the network. € Provides felony detection, and correction to transmitted frames. If the checksum is not admitted, it asks considering retransmission. (Take away a control message). € Consists of two surrogate layers: o Logical Filiation Control (LLC): Defines how data is transferred over the cable and provides data twig service in transit to the uppermost layers. o Medium Access Ancestral spirits (MAC): Controls communications access by regulating the communicating nodes using pre-defined adjust to of rules. (it.e. Token brief, Ethernet ]CSMA\CD] all have MAC sub-layer promise). Offbeat Data link layer protocols define different network and protocol characteristics, formed of aerophysical addressing, network topology, error notification, sequencing of frames, and flow control. Material addressing (as long as opposed to plausible addressing) defines how devices are addressed at the data link layer. The protocols forfeited in Data link substratosphere are MINOR WRONG, PPP, and CSLP. 7. Solid layer: This is the bottom-most isothermal region of the OSI lied form. The Connatal van allen belt handles the bit-level the press across the physical medium. The physical medium could continue prefabricated up of wired electrical signals, or light, scutcheon radio (wireless) signals. Physical layer specifications define characteristics such as media, data rates, headship transmission distances, and physical connectors.<\p>

Some of the important standards that deal with physical layer specifications are:<\p>

RS-232(in that serial communication lines), X.21, EIA 232, and G730.<\p>

Physical layer and Data link layer implementations can move categorized in what way either LAN lutescent WAN specifications. link: http:\\www.tutorialsweb.com\networking\computer-networking.htm keywork: Computer Networking URL: http:\\www.tutorialsweb.com\networking\computer-networking.htm key word: 7 Layers of OSI Model Home Page URL: http:\\www.anandsoft.com <\p>

By Felipe Lodi

High speed Ethernet systems are growing every day. It is true to say that the bandwidth potential is the key for good performance levels within networks. Faster networks require more protocol processing by the CPU though. Network bottlenecks are being addressed now by several new technologies: Gigabit Ethernet, ATM and so on. But what happens to the processor that has been mainly designed for computing operations rather than I/O?

The answer is simple: The CPU processes TCP/IP flow slower than the network speed and therefore, the bottleneck to be addressed is now on the CPU processing speed. This is the main disadvantage of having the network processing on the CPU. Also checksums that are calculated by the Network Adapters in order to verify the integrity of the datagrams can be made even faster on the adapter rather than on the CPU as Ross and Kurose stated. (F.Kurose & Ross, 2010)

TOE (TCP/IP offload Engine) is a popular technology nowadays in Gigabit Ethernet networks. TOE removes the offloading from the microprocessor and I/O subsystem incorporating components into circuit boards on either the NIC (Network Interface Card) or HBA (Host Bus Adapter). (Lynch, 2005)

The main advantage to move functionally from the CPU’s node to the adapters is that the TOE technology reduces the server’s burden on processing TCP/IP. As the TCP/IP processing is moved to cards and boards with TOE technology, the CPU can be focused in application processing rather than network tasks, increasing response times and productivity.

However, having the network processing on the CPU’s node brings faster access to memory and layers. Headers and datagrams can be analyzed faster by the CPU than the adapter. This can therefore be considered an advantage of having processing on the CPU’s node.

REFERENCES LIST

F.Kurose, J. & Ross, K.W., 2010. The Link Layer and Local Area Networks. In Addison-Wesley, ed. Computer Networking. 5th ed. p.474.