Beginning to Network Communication

Host = end system

Internet network application'larını run eder.

Communication links : fiber , copper , radio, satellite  iletişim bunlarla gerçekleşir
Bandwith ,transmission rate'ine denir.

Router : Forward packet , packet : chunks of data

Protocols: Mesaj göndermeyi ve mesaj almayı yönetir. Örnek : TCP, IP, HTTP, Skype, Ethernet

Internet : Network'lerin network'ü. Loosely hierarchical'dır. Public Internet vs Private Intranet.

Internet standards : RFC: Request for comments ,  IETF: Internet Engineering Task Force

What’s the Internet : a service view
Communication infrastructure : enables distributed applications(distributed application'ları enable eder) : Web, VoIP, email, games,e-commerce, file sharing

Communication services provided to apps:
- reliable data delivery from source to destination
- "best effort" (unreliable) data delivery
-connectionless , connection-oriented

Protocols define (1) format, (2) order of msgs sent and received among network entities, and (3) actions taken on message transmission, receipt
Protokol 3 şeyi define eder : Format , Order  Action

a human protocol and a computer network protocol








protocols : TCP , IP,HTTP,FTP,PPP,...

Network structure'ına daha yakından bakalım:

Network edge : applications and hosts

1. end systems :  network application'larını run eder.Network'ün edge'leridirler. Örnek : Web,email.
2. Client/server model:  client host'u , always-on server'dan service isteğinde(request) bulunur ve alır(receive).Örnek : Web browser/server ; email client/server.
3. Peer-to-peer model : minimal (or no) use of dedicated servers(dedicated server'ların ). Örnek: Skype, BitTorrent.

Access networks, physical media : wired and wireless communication links.
      End system'leri edge router'ına nasıl bağlarız :

1. residential access nets
2. Institutional access networks (school,company)
3. Mobile access networks

     Şunları hatırla:
     -Bandwidth(bits per second) of access network?
     - shared or dedicated ?

Network core : mesh of interconnected routers , Network of networks

r

    point to point access ->
            
      Dialup via modem

• direct access to router . Max 56 Kbps olabilir çoğu zaman daha düşüktür.
• Can't surf and phone at the same time : can't be "always on".

      DSL: digital subscriber line

• deployment
• max 1Mbps upstream (typically < 256 kbps)
• max 8 Mbps downstream (typically < 1 Mbps)
• dedicated physical line to telephone central office

      cable modems ->

• HFC: hybrid fiber coax . Asymmetric : up to 30Mbps downstream, 2 Mbps upstream
• cable ve fiber network'leri evleri ISP router'ına bağlar. homes share access to router
• deployment : available via cable TV companies

       





Cable Network Architecture: Overview

the fundamental question: how is data transferred through net?

mcircuit switching: dedicated circuit per call: telephone net

mpacket-switching: data sent thru net in discrete “chunks”

http://wiki.answers.com/Q/Can_you_connect_a_wireless_router_to_a_router#slide=4
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