Brainstorming of Network Communication

Regarding TCP, UDP, IP, and routing:
What are the important fields in the TCP, UDP, and IP headers? Without these fields, the protocols would clearly not “work”. 
 TCP = ports #s, seq/ack #s, flags, checksum, and windows size
UDP = port #s and checksum

IP = addresses, checksum for header

What are the important attributes for a good routing algorithm? 

 Fast, simple, little traffic, no loops, converge to optimum 

 

What is a key difference between a distance vector and link state routing protocol? 

DV uses neighbor exchange of routing vectors, LS uses broadcast of link state 

information.

Regarding Application Layer :
We say that FTP has out-of-band control. What do we mean by that? 

 We mean that commands and data flow across different TCP connections.

How is it that sender addresses can be spoofed in an email? 
 There is no authentication of commands in SMTP. Thus anyone with access to an SMTP

server can enter any from address (i.e., spoof who they are).

What is HTTP (in about 100 words, use a drawing if it will help)? 
 The HyperText Transfer Protocol is a stateless application layer protocol. HTTP is
used to transfer web content between a browser application (client) and an HTTP server.
All web content is identified by a URL. HTTP is a request response protocol that uses
TCP for assured delivery. HTTP uses ASCII encoded headers. The HTTP GET command
retrieves HTML files and other objects. The GET header includes the URL of the object
and other optional fields such as capability, language, and so on. The response
includes a response header with a response code (code 200 is OK and 404 is page not
found). Other commands include POST and HEAD.



Regarding the basics of computer networks and the Internet. 

What are the fundamental measures of interest for a communications system? 
 Throughput, delay, loss, cost, mobility, robustness, and secrecy

What are the basic tasks or functions of a communications system? 
 Message formatting, error detection and recovery, addressing, routing, flow control,
system management, security, and QoS

Precisely define protocol and interface (as we described them in class). 
 A protocol is a complete set of rules regarding information exchange between same level
layers between sites. An interface is a complete set of rules regarding information

exchange between adjacent layers in a single site.

Regarding the Internet

What are the four causes of packet delay? 

 Processing, transmission, propagation, and queueuing. 

 

What are the possible mechanisms of packet loss? 

 Buffer overflow (e.g., due to congestion) and electrical noise corrupting a packet 

 

What is a tool that can be used to determine the number of hops to a destination and the round trip time (RTT) for each hop? 

 traceroute 

What is quality of service? 

 QoS is the requirements an application places on the network. 

Resources :

http://www.proprofs.com/quiz-school/story.php?title=networking-midterm
(http://www.proprofs.com/quiz-school/search.php?search=network)
http://courses.engr.illinois.edu/cs438/sp2012/assignments/midterm-ol-s12-sol.pdf
http://www.cram.com/flashcards/networking-midterm-2433165
http://www.cram.com/flashcards/network-midterm-exam-study-stet-2441344
http://www.csee.usf.edu/~christen/class2/oldExams/ex2_1_sol_spr06.pdf
http://www.cs.princeton.edu/courses/archive/spr11/cos461/docs/lec12-midreview.pdf
http://www.cs.uiuc.edu/class/fa06/cs438/CS438-MidtermSolutions.pdf
http://server.casa.umass.edu/~zink/ECE374/Exams/MidtermII_Exam_With_Fall_2011_SOLUTIONS.pdf
http://server.casa.umass.edu/~zink/ECE374/Exams/MidtermExam2010withsolutions.pdf
http://cs.brown.edu/courses/cs196-5/f13/handouts/midterm-s12.pdf

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
https://www.google.com.tr/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CDcQFjAA&url=http%3A%2F%2Fwww.cs.umd.edu%2F~shankar%2F417-F01%2FSlides%2Fchapter1a-aus.ppt&ei=C4v3Up_nG6Wd0wXW6YCABQ&usg=AFQjCNGTXtYOutfpEv1h8xO1ohhJFgJ3tQ&sig2=JITURSpfmqVaUEpSlL935w