Data Communication sey Ta'aruf

[Masood]

Chapter 01: Data Communication sey aik ta'aruf






Data Communication aaj kal key modern computer system ki buniyad hai, jiski yeh demand hai keh data aik jagah sey doosri jagah muntaqil ho sakey. Zel mein di gaii misalein in mein chand aik hain:

• Aik central computer jis per computer programs installed hon, aur jis key saath terminals jurrey hon. Yeh terminal aik bohat wasee elaqey mein bhi ho saktey hain. Yahan per data terminals aur central computer key darmiyaan harkat karta hai (Centrilized Data System)
• Mukhtalif Network key components jo net cables key zariyry aik doosrey sey jurrey hon
• Clien/Server-Solution jis mein data aik ya ziyada server per hota hai aur client yani users key pc sey us sey kaam letey hain - yeh bhi network key zariyry mumkin hai.
• Distributed Systems: aik ya ziyada computer jin per resources hon, jab aik user aik program shuru karta hai, to distributed systems khud manage kartey hain keh kis computer/server per yeh chaley ga
• Distributed Databases: computers/servers jin per database resourced mojood hon aur yeh faisla keh kis system sey information hasil ki jaey is per depend karta hai keh user ki input kya hai, agar database ya database ka aik makhsoos section hai to wohi harkat mein aata hai

[Masood]

Re: Data Communication sey Ta'aruf

1.1 Data Communication ki Saakhat

Har computer solution ki apni demand hoti hai, aur har aik solution ki demand mein bohat farq hota hai keh data ki tarseel kitni jaldi ho issey ham LATENCYkehtey hain, ya kis raftar sey data ki tarseel ho. Raftar ko napney ka paimana bit per second (bps) hota hai.

Aik doosri term jo ham istimaal kartey hain, woh RELIABILITY hai. Is sey murad yeh hai keh data ki tarseel key liyey woh service mojood honi chahiyey jo tarseel ki demand hai. Agar ham data ki tarseel bohat jald chahtey hain magar hamarey paas woh dhancha hi nahin jo yeh mohayya kar sakey to be'kar hai.

Chunkeh tarseel ki jo zariyey hain, woh aksar bohat faasley per hotey hain, aur data tarseel key hack honey ka khatra bhi mojood rehta hai, hackers almost all the time hacking ki koshish mein rehti hai, lehaza tarseel ko protect karna bhi zaroori hai.

Delay
Data Communication System per kis kisam ki demand hai yeh kehna bohat mushkil hai. Is liyey ham data traffic ko do hisson mein bant'tey hain:

• Realtime Traffic
  • Realtime traffic ki aik misaal TV key woh signals hain, jin mein audio (yani aawaz) aur video (yani tasweer) dono ki tarseel aik hi waqt mein honi chahiyey aur zara si der sey gadmad ho jaey gi. Agar sooti lehrein delay hongi to aawaz tasweer key baad aaey gi.
  • Aik network jis per sey realtime traffic ki tarseel ho, usko is qabil hona chahiyey keh aik khaas limit mein rah ker delay pedah karey warna quality mein nuqs ho ga. Magar yahan per yeh hai keh receiving computer mein itna buffer hona chahiyey keh woh sending information ko mehfooz kar sakey
  • Pehley pehal ATM Network yeh sahoolat deta tha, magar aaj kal FastEthernet waghera bhi yeh sahoolat detey hain
• Aam Traffic
  • Aur aam traffic ham har us traffic ko kehtey hain, jo do computers key mabain hoti hai.

Raftar (Speed)

aik bohat aham baat data communication mein yeh bhi hai keh jis data ki tarseel ki jaa rahi hai, woh kis miqdaar mein hai, aur khaas ker kitna data fii second muntaqil karna hai.


Shuru sey ley ker aik bohat muddat tak network per data ki yeh tarseel bohat kam raftar sey hoti rahi hai. Magar ab yeh raftar bohat tez bhi ho sakti hai, aaj kal Gigabit switch bhi miltey hain.


Aik aam computer sey agar ham information type kartey hain jo kisi database server per update hoti hai, to is mein bohat hi kam data traffic generate hoti hai. Iski aik misaal bankon mein lagey huwey woh terminals hain jin mein bohat sari transaktions hoti hain magar sirf text based, aisi transactions aik 9.6 kbps (9.6 kilobit per second) ki line per kaam dey sakti hain.


Waqt key saath saath ab ziyada tar aisi applications istimaal mein aaney lagi hain, GRAPHICAL USER INTERFACE (GUI) istimaal karti hain. Aisi application ki network demand ziyada hoti hai kyun keh is graphical communication heavy hoti hai.


Aik SVGA-tasweer jo aam computer per nazar aati hai, amooman 2.5 Mb hoti hai. Ab agar yeh tasweer jo 2.5 Mb ki hai, aik network per muntaqil ki jaey aur time limitation 2 second ho to iskey liyey:

2.5 x 10^6 /2 = 1.25 Mbps

ki speed sey network per data ki tarseel zaroori hai.

Aur agar 2 screens sey aik hi waqt mein aisi tasaweerein muntaqil karni parrein to phir raftar 2.5 Mbps honi chahiyey. Yeh SVGA-screen ki misaal hai.

Agar koi high scalability ki application ho jaisey CAD/CAM hai to demand 10 sey 100 gunah ziyad ho sakti hai - yeh Network ko support karna chahiyey.

Datatrafic ki aik aur misaal, filesharing hai. File sharing aaj kal key network per aik bohat aam si baat ho gaii hai, jahan per chand kilobytes sey ley ker kaii kaii hazar kilobytes aur Gigabyte tak data transfer kiya janey laga hai.

Agar ham misaal key taur per sirf 10 MB ki aik file download karein aur ham chahein keh yeh file sirf 10 second mein download ho, to network ki speed yeh honi chahiyey:

10 x 10^6 x 8 /10 = 8 Mbps

[Masood]

Re: Data Communication sey Ta'aruf


Table 1.1 Typical application demand to Networks speed.



Realtimes trafic network mein delay key saath saath speed per bhi demand karti hai. Audio- aur videosignals network key zariyey muntaqil honey sey pehley amooman digital technology mein convert kiyey jatey hain. Digital data transmission ZEROs aur ONEs mein hoti hai.

Aik aam sooti-signal (audio signal) jo telefon ki quality mein ho, uskey liyey 64 kbps ki speed darkar hoti hai.

Is liyey agar aik telefon conversation ki jaey, jis mein do fareeq hon, to uskey liyey 2x64 kbps ki speed darkar hoti hai.

10 telefon calls jo aik hi saath ki jaein unkey liyey phir 1.28 Mbps ki speed chahiyey hoti hai.

Aap ney amooman woh sites dekhi hongi jahan per music ki CD's share ki jati hai, aisi aik CD network per share karney key liyey 706.5 kbps.

[Masood]

Re: Data Communication sey Ta'aruf


Table 1.2 Aam application ki demand


Aaj kal jadeed applications aur audio, video ki demand barhti jaa rahi hai. Is demand ko kam karney key liyey signal bhejney sey pehley ussey compress kiya jata hai jo receiving end per decompress kiya jata hai.

Iski misaal yun lijiyey keh TV signal jab sender sey chalta hai to woh compressed hota hai, jab woh TV antenna key zariyey mosool hota hai, to TV ussey decompress kar key pesh karta hai.





Reliability

Jab kisi bhi company mein applications chalti hain to Network per yeh demand ki jati hai keh woh 100% of time up and running ho.


Farz kijiyey keh aik company jo hawaii jahaz ki tickets book karti hai, agar uska Network accessible nahin ho ga to company ko millions of dollers ka nuqsaan ho sakta hai aur us company ka image bhi damage hota hai.

Network ko reliable karney key liyey reliable Net Devices (NICs, Routers, Switches waghera) istimaal kiyey jatey hain aur iskey saath saath har device ko redudant bhi kiya jata hai. Redudant karney sey murad yeh hai keh kisi bhi device ki mutbadil device usi tarha function mein laga di jaey keh agar main device funtion na karey to redudant uski jaggah khud ba'khud kaam karna shuru kar deti hai - yeh reliable Network ki bohat barri misaal hai.

Mazeed baraan yeh keh aik aisa Computer System install kiya jaey jo Network mein istimaal honey waley tumaam'tar component ko MONITOR karey aur uski monitoring ki report kisi aik screen per dikhaii jaey. Aisey aik system koi ham Network Management System (NMS) boltey hain.

Security

Jab kisi sey IT System sey data ki tarseel hoti hai, aur woh aik barrey jughrafiyaii elaqey per ho to security ka bohat barra issue hota hai.

Is issue ko hal karney key liyey teen baton ka khiyaal rakha jata hai:

1. confidentiality
   Data, jo communication channels per bheja jaey, aasani sey hasil kiya ja sakta hai. Data ko encrypt kar key send kiya jaey!
   
2. integrity
   Data, jo communication channels per bheja jaey, raastey mein tabdeel kiya ja sakta hai, is tarha keh jo asal message hai, woh apney muqaam tak na puhnch sakey
   
3. authentification
   Khasoosan un transactions mein jahan credit cards ki informations hon, ya bank account waghera involve hon, wahan per SENDER aur RECEIVER ko aik doosrey key identy per yaqin hona chahiyey.
   

[Masood]

Re: Data Communication sey Ta'aruf

1.2 Data Communication Technology

Network per jab data ki tarseel hoti hai to woh kabhi aik hi waqt mein bohat ziyada data ki muntaqli ki soorat mein hoti hai, aur kabhi kabar koi bhi data move nahin hota. Is ko mufeed bnaney key liye Network mein ziyada aur muassar component istimaal kiyey jatey hain.

Company key liyey mufeed'tar yehi hai keh aik hi tarz ka aik hi Network istimaal kiya jaey.

Network per jo resources istimaal hoti hain, unki ki aksar oqat aik hi waqt mein demand hoti hai, aur agar aik hi waqt mein Network per mojood resources ko istimaal kiya jaey to un mein takheer pedah ho sakti hai.

Jab Network per bohat sari applications sey data ki tarseel hoti hai to har type ka data aik hi waqt mein muntaqil nahin ho sakta. Is ko control karney key liyey data ko prioritize kiya jata hai aur aik kisam key data ki muntaqli ko pehley janey ki ijazat hoti hai, aur doosri type key data ko baad mein.

Is type ki prioritize sey Network per data load behtar taur per taqseem kiya ja sakta hai.

Aik aur factor jo asar andaz hota hai, woh data ki tarseel mein nuqs hai. Transmission errors.


LAN, WAN, MAN, GAN aur internet.





Network ko ham amooman 3 main areas mein taqseem kartey hain:

1. Local Area Network (LAN)
   Yeh amooman aik hi building ya company mein istimal kiya jata hai aur is mein speed 10 - 100 Mbps ki hoti hai (aaj kal Gigabit Network bhi use hota hai)
2. Wide Area Network (WAN)
   Yeh aik purana tareeqa hai jis mein aik telephone ki opeating company X.25, ISDN ya Frame Relay ka Network mohayya karti hai.
3. Metropolitan Area Network (MAN)
   Yeh amooman do ya ziyada shehron key darmiyan Network ko kehtey hain.

Iskey elawa aaj kal Internet ko bhi aik Global Area Network ya GAN mein aata hai jis mein Network resources duniya bhar mein istimaal kiyey jatey hain.



Network Component

Khaka 1.1 ko ghaur sey dekhiyey. Is mein do computer aapis aapis mein communication kartey waqt aik Network ka sahara letey hain, yeh Network jo as khud bohat sarey chhotey barrey Networks sey mil ker bana hai, issey ham zuban-e-aam mein internet kehtey hain. Jo zeli Network hain inhein ham SUBNET bhi kehtey hain, yeh LAN, WAN, MAN kisi aik sey ban saktey hain aur aapis mein Network compnents key zariyey communicate kartey hain.

Har subnet ko aik Network Interface defince karti hai, jis mein yeh baat tafseelan code ki jati hai keh yeh subnet doosrey aur doosrey is subnet sey kis tarha communicate karein gey.

Is defination mein barqi ro sey ley ker voltage, current, Switchboard type tak define kiya jata hai aur yeh bhi keh data kaisey harkat karey ga aur receiving end ka mukammil address bhi define kiya jaey ga.

Tumam Network devices ko jo shay physcially 'jorti' hai ussey transmissionchannels kehtey hain jo keh copper cables, RJ45 cables, fiber opticial cables tak aur Radio Wave tak sabhi shamil hain. Chunkeh in ka taluq PHYSICALLY LAYER sey hota hai.

Amooman tarseel SERIAL hoti hai - yani aik key baad doosra bit transmit kiya jata hai.

Jab aik computer kisi doosrey computer sey internet key zariyry communicate karta hai, to yeh APPLICATION PROGRAMMING INTERFACE (API) key zariyey sey hota hai.

Jab is API ko istimaal mein laya jata hai to yeh define karta hai keh receiving computer per kaunsa program hona chahiyey, jo issey samajh sakey - jaisey MSN sey MSN communication.

Operating System ka aik kaam yeh bhi hota hai keh woh aik computer per mojood jitney bhi resource hain, jaisey RAM, Processor waghera, inhein behtar tareeqey sey utilize karey.

Koi sab bhi Operating System istimaal kiya jaey, har aik mein aik communication protocolstack hona chahiyey, takeh doosrey computer key saath communicate kiya jaa sakey.

Aik protocolstack amooman aik sey ziyada protocol sey mil ker banta hai jis mein aik layer doosrey layer ki mojood service ko istimaal karta hai.

Aik protocal aik precise description hai keh aik sending aur aik receiving party kaisey communicate karey. Yani aik set asool jo murattab kiyey jaa chukey hain, ussey protocal kehtey hain.

Network sey wabasta protocalstack mein yeh khoobi honi chahiyey keh woh doosri devices sey communicate karey aur saath mein Network ko doosri device ka address btaey.

Ziyada tark function jo aik Network related protocal mein hain, woh nechley layers mein define kiyey gaey hain jo hardware aur firmware mein hotey hain. Magar aksar higher level key funktion software mein implement kiyey jatey hain.

Is tarha agar aik application 5 MB ki file transfer karey to application related protocal stack pehley is file ko chhotey chhotey hisson mein bantey ga, phir ussey neechley level key layers key supurd karey ga keh unki tarseel ho sakey.

Receiving computer phir un chhoti chhoti files ko sab sey pehley neechley level key layers per hasil karta hai, unhein aapis mein jorrta hai aur application related protocol key hawaley karta hai, jo us file ko phir sey 5 MB ki soorat mein dekhta hai.

Aik aur aham function jo application related protocol mein hai woh end-to-end control hai jo sender aur receiver key mabain tay pata hai. Agar koi data tarseel mein nuqs ho to application ussey check karti hai, nuqs ki soorat mein woh retransmision hoti hai.

Application Related protocol ki yeh bhi zimmedari hoti hai keh jo data ussey wosuul huwa hai, uski jaanch parrtaal karey. Yeh is liyey bhi zaroori hai keh data kaii aqsaam mein muntaqil kiya jata hai, har kisam ka data har application nahin parh sakti - misaal key taur per IBM key Mainframe per aik COBOL mein likha huwa program aik hindsey ko aik tarha parhta hai jab keh wohi hindsah C++ mein doosri tarz per parha jata hai. (Ya jaisey MAC aur PC mein farq hai)

Protocolstack ki bohat sari qismein hain, jin mein TCP/IP, SNA, OSI og NetWare ziyada mashoor hain, magar in mein har kisam apni ham'jins hi sey communicate kar sakti hain.

[Masood]

Re: Data Communication sey Ta'aruf

1.3 Data Communication History

Data Communication aur Information Technology ki history aik jaisi hai, kyunkeh jahan jahan Information Technology ney taraqi ki, taghayyur paya wahan wahan Data Communication ney bhi kiya.

Jab pehla pehla Centralized Dataprocessor wajood mein aaya, to woh sirf aik batch-related dataprocessor tha, jis mein programs aur input-data aik alag computer sey dala jata tha. Khaka 1.2 mein dekhiyey keh pehla Mainframe kaisey kaam karta tha. Mainframe aur woh computer jis sey information daali jati thi, woh aik hi jaggah per hotey they.

Doosra barra hadf yeh hasil kiya geya keh aik Mainframe ko is qabil bnaya geya keh uskey saath bohat sarey terminals jorrey jaein, jin per sey programmer Mainframe per online programs tayyar kar sakein.

Ab aik aisey kamrey mein jahan Mainframe ho, wahan per itney ziyada users nahin ho saktey they to next step yeh liya geya keh printers, terminals waghera data communication channels key zariyry munsalik kiyey gaey, yun kaii aik kamron sey Mainframe tak risaii hasil honey lagi. Khaka 1.3.

Naey processors tayyar huwey jo Centralized Mainframe per load ko kam kar sakein. Is ko Fron End Processor (FEP) kaha geya. Saath hi mein naii type key communication control wajood mein aaey jo terminals aur printers ko control kar sakein jo wide area per mojood they.

Iskey taraqi key saath saath 1980 key aaghaz mein PC (Personal Computers) wajood mein aaey. (yahan per aik baat ki wazahat kar doon keh aik terminal aur PC mein bohat barra farq hota hai. PC mein apna processor, apni RAM, apney programs, sab kuchh local PC per hota hai, jab keh aik terminal aik IDIOTICAL PIECE OF HARDWARE tha jis mein na koi apna processor, na koi apni RAM, na koi apni harddisk huwa karti thi, woh sirf aik terminal tha jis per type kartey they, sari processing Mainframe ya Centralized Computer per huwa karti thi).

PC ki maqbooliyat mein zabardast izafa huwa aur PC ney terminals ki jaggah Network mein leni shuru kar di.

Mainframe hamesha hi bohat mehnga aur costly affair raha hai. Aur waqt key saath saath yeh aarzu rahi hai keh kisi tarha Mainframe ko replace kiya jaey. PC's ki maqbooliyat aur PC ki developement sey Servers wajood mein aaey aur Servers ney Mainframe kam kardiye aur ab almost khatam ho chukey hain.

Magar Servers tak access hasil karney key liyey bhi Network ki zaroorat hai. Khaka 1.4 issi tarz key aik Network ko illustrate kar raha hai, jis mein Servers key saath PCs jurrey huwey hain.

END OF CHAPTER 1

[Masood]

Re: Data Communication sey Ta'aruf

1.4 Sawalaat:

1. Data Communication ki khasoosiyat biyaan kijiyey.
2. Aam data tarseel Network key liyey kya demand karti hain?
3. Realtime trafic kya hoti hai? Aur iski kya demand hai?
4. Delay aur Speed mein farq kya hai?
5. Data ki tarseel mein kaun kaun sey security issues ho saktey hain?
6. Network mein reliablity barhaney key liyey kya kiya jaa sakta hai?
7. Bohat sarey saarfeen key mabain honey waley Network mein kya faidey hain aur kya nuqsanaat?
8. Kaisey is baat per control hasi kiya jaa sakta hai keh jo important trafic hai, woh pehley transmit ho?
9. LAN, WAN, MAN aur GAN mein kya farq hai?
10. internet aur Internet mein kya farq hai?
11. Network mein jo khaas khaas devices hain, unhein biyaan kijiyey
12. Data Communication mein STANDARDS kya faidah detey hain?
13. Data Communication ki tareekh key khaas khaas batein biyaan kijiyey
14. Aik Protocol kya hai?
15. Aik Protocolstack key jo aham tareen functions hain, woh biyaan kijiyey.

[askfriends]

Re: Data Communication sey Ta'aruf

great info, thanks

[Nadia khan]

Re: Data Communication sey Ta'aruf

very nice sharingbou:

[SAAD]

Re: Data Communication sey Ta'aruf

Thankss for sharing.
Kiya routing aur gatway ke bary mien kuch mallumat mil sakti hain.

[hadeeqa4u]

Re: Data Communication sey Ta'aruf

VoIP BASICS

VoIP lets you make toll bypass voice and fax calls over existing IP data networks instead of the public switched telephone network (PSTN). Today businesses that implement their own VoIP solution can dramatically cut national and long distance costs between two or more locations.
As data communications emerged, companies paid for separate data lines so their computers could share information, while voice and fax communications were still handled by the PSTN. A corporation will often have two separate parallel networks often linking the same locations within the corporation
Today, with the rapid adoption of IP, we now have a far reaching, low-cost transport mechanism that can support both voice and data. A VoIP solution integrates seamlessly into the data network and operates alongside existing PBXs, or other phone equipment, to simply extend voice capabilities to remote locations without the cost of managing parallel networks.
:bou:

[hadeeqa4u]

IP Telephony

IP Telephony

:bday7:

[Soulmate]

Re: Data Communication sey Ta'aruf

buhat umdah lecture hai Masood brother

[kutkutariyaan]

Re: Data Communication sey Ta'aruf

Good Class :)

Thanks for ur Hard Work :D:

Jitni bhi Tareef ki jaee kam hai :writer

Reputation ka chota sa Nazrana Qabool kerain. :THANKS:

[Tanha Hassan]

Re: Data Communication sey Ta'aruf

Great work