Tuesday, 31 July 2012
Monday, 30 July 2012
Important points for Chapter 4
The purpose of the transport layer is to ensure that data travel successfully from one end to another end across the network. The port numbers indicate the application the data belongs to. At the transport layer, the port numbers are added into or removed from the original data
When the client communicate to the HTTP server, the well known port 80 is used as the destination port. For the source port, the PC will assign a random port number. The address and port number combination forms a socket. The port numbers are reversed on the return path.
In the transport layer, there are two types of protocols
The slow and steady protocol
TCP is a reliable protocol which sequence data packets before sending and acknowledge it once the packets are received. Due to the amount of acknowledgements needed, it is too slow for streaming applications. It is useful for application which requires accurate and reliable data.
Window size - Max number of bytes received before sending ack
Sequencing - Data packets are arranged in the right order after receiving
The fast and furious protocol
UDP is a non reliable protocol which has no sequence numbers or acks. The main purpose of this protocol is to allow fast data transmission. Packet loss during transmission are ignored by the end devices.
The key information at transport layer is the port numbers. The port numbers indicate the data belong to which application. For example, port 25 is SMTP and it is used by the email client. On the other hand, port number 53 is DNS and it is used by the resolver nslookup to resolve domain names.
In order for applications to send and receive data concurrently across the network, we need to multiplex the data. By multiplexing the data, we mean that the data is divided into segments and and take turns to be transported across the network. This appears to the user that the application are running concurrently.
To start a TCP session, the end devices need to perform a 3 way handshake. For UDP session, it is not needed. TCP reorder packets while UDP does not reorder. If there are packet losses during transmission, TCP request for retransmission while UDP does not.
When connected to servers running on TCP or UDP, the well known ports are used while random ports are assigned to the PCs.
When the client communicate to the HTTP server, the well known port 80 is used as the destination port. For the source port, the PC will assign a random port number. The address and port number combination forms a socket. The port numbers are reversed on the return path.
In the transport layer, there are two types of protocols
The slow and steady protocol
TCP is a reliable protocol which sequence data packets before sending and acknowledge it once the packets are received. Due to the amount of acknowledgements needed, it is too slow for streaming applications. It is useful for application which requires accurate and reliable data.
Window size - Max number of bytes received before sending ack
Sequencing - Data packets are arranged in the right order after receiving
The fast and furious protocol
UDP is a non reliable protocol which has no sequence numbers or acks. The main purpose of this protocol is to allow fast data transmission. Packet loss during transmission are ignored by the end devices.
The key information at transport layer is the port numbers. The port numbers indicate the data belong to which application. For example, port 25 is SMTP and it is used by the email client. On the other hand, port number 53 is DNS and it is used by the resolver nslookup to resolve domain names.
In order for applications to send and receive data concurrently across the network, we need to multiplex the data. By multiplexing the data, we mean that the data is divided into segments and and take turns to be transported across the network. This appears to the user that the application are running concurrently.
To start a TCP session, the end devices need to perform a 3 way handshake. For UDP session, it is not needed. TCP reorder packets while UDP does not reorder. If there are packet losses during transmission, TCP request for retransmission while UDP does not.
When connected to servers running on TCP or UDP, the well known ports are used while random ports are assigned to the PCs.
Chapter 4 slides uploaded
Hello ! The presentation slides for Chapter 3 are as follows:
Summary Slides (Beginner)
https://www.dropbox.com/s/08ohn1ubdv6w1tz/Chapter_4_Overview.ppt?m
Slightly Detailed Slides (Intermediate)
https://www.dropbox.com/s/wx0kcmo39ah22g9/Expl_NetFund_chapter_04_Trans_Layer.ppt?m
Detailed Slides (Advanced)
http://ibizzone.ite.edu.sg/elearning/mod/resource/view.php?id=1293
Quiz
http://ibizzone.ite.edu.sg/elearning/mod/quiz/view.php?id=1302
Follow your skill level and go through the slides. If you feel comfortable, go through the higher level slides as well and finally, attempt the quiz
Summary Slides (Beginner)
https://www.dropbox.com/s/08ohn1ubdv6w1tz/Chapter_4_Overview.ppt?m
Slightly Detailed Slides (Intermediate)
https://www.dropbox.com/s/wx0kcmo39ah22g9/Expl_NetFund_chapter_04_Trans_Layer.ppt?m
Detailed Slides (Advanced)
http://ibizzone.ite.edu.sg/elearning/mod/resource/view.php?id=1293
Quiz
http://ibizzone.ite.edu.sg/elearning/mod/quiz/view.php?id=1302
Follow your skill level and go through the slides. If you feel comfortable, go through the higher level slides as well and finally, attempt the quiz
Monday, 23 July 2012
Important points for Chapter 3
Application layer is the starting point and the ending point of data communication
When data is transmitted, data will be processed through various layers of the OSI model. This is known as Encapsulation. Headers are added.
When data is received, data will be processed through the same layers of the OSI model. This is known as De-encapsulation. Headers are removed.
Devices at 2 points must adopt the same communications model, different models do not work
Application layer has 3 entities - Applications, Services and Protocols
Applications - Microsoft Outlook, FileZilla, LimeWire, Bearshare
Protocols - Rules to govern the transmission of data
Services - Combination of Application and Protocols to provide services such as email, files upload and messaging.
As we know that the OSI model is a reference model while the TCP/IP model is a protocol model, the application layers at both models are related. The application, presentation and session layers at the OSI model is equal to the application layer at the TCP/IP model. The main reason is due to legacy issues as OSI model is developed after TCP/IP model and encompass more features compared to the latter model.
The various protocols for the application layer are DNS, HTTP, SMTP, POP, DHCP. All these protocols are important for your tests and exams
Most application layer protocols followed the client server model. The client sends a resource request to the server and the server will process the request and allocate the resources and send a response back to the client. Usually there is one server connected to multiple clients
For telnet, the server is running a daemon which actively listen to telnet requests from clients. When there is a request, the server will create a child process to handle the telnet session. This way, the server is able to monitor various clients at the same time.
Peer to peer networking model is different as any PC can be both client and server at the same time. Information is processed simulataneously at both ends and the transmission is full duplex.
Main function of DNS is the resolve domain names to ip addresses. When a user enter a domain name into the browser, the domain name is passed to the resolver (nslookup). The resolver will query the domain server for the correct ip address, if it is found then the ip address is passed to the PC. The PC will direct the data packets using the ip address.
HTTP is responsible for reliable transmission for web data from one end to another. It is achieved by means of POST and GET requests to the web server.
SMTP is used to send and forward mail information. MUA is your email software while MTA is used as a forwarder to forward email information to the right email server. The MDA is used to store your email on the server before it is transferred to the MUA. The MUA will retrieve email from the MDA using POP.
Telnet is used to create remote access to a particular device. The transmission is using in plaintext and is not secure. Nowadays, we used SSH (secure shell) to perform remote access.
SMB (Server Message Block) is a protocol which is used for folder and file sharing over the network. It is used mainly for Microsoft Windows. It follows a server and client model
Gnutella, on the other hand, is a protocol for folder and file sharing over the network using the peer networking model. It is used by bearshare and limewire. There is another protocol known as BitTorrent which is also peer to peer.
DHCP is used for dynamic assignment of ip addreses to clients. The four main messages in a DHCP exchange are DHCPDISCOVER, DHCPOFFER, DHCPREQUEST, DHCPACK. For a large enterprise network, having DHCP will remove a lot of manual work needed to configure ip addresses.
Need to remember the port numbers.
When data is transmitted, data will be processed through various layers of the OSI model. This is known as Encapsulation. Headers are added.
When data is received, data will be processed through the same layers of the OSI model. This is known as De-encapsulation. Headers are removed.
Devices at 2 points must adopt the same communications model, different models do not work
Application layer has 3 entities - Applications, Services and Protocols
Applications - Microsoft Outlook, FileZilla, LimeWire, Bearshare
Protocols - Rules to govern the transmission of data
Services - Combination of Application and Protocols to provide services such as email, files upload and messaging.
As we know that the OSI model is a reference model while the TCP/IP model is a protocol model, the application layers at both models are related. The application, presentation and session layers at the OSI model is equal to the application layer at the TCP/IP model. The main reason is due to legacy issues as OSI model is developed after TCP/IP model and encompass more features compared to the latter model.
The various protocols for the application layer are DNS, HTTP, SMTP, POP, DHCP. All these protocols are important for your tests and exams
Most application layer protocols followed the client server model. The client sends a resource request to the server and the server will process the request and allocate the resources and send a response back to the client. Usually there is one server connected to multiple clients
For telnet, the server is running a daemon which actively listen to telnet requests from clients. When there is a request, the server will create a child process to handle the telnet session. This way, the server is able to monitor various clients at the same time.
Peer to peer networking model is different as any PC can be both client and server at the same time. Information is processed simulataneously at both ends and the transmission is full duplex.
Main function of DNS is the resolve domain names to ip addresses. When a user enter a domain name into the browser, the domain name is passed to the resolver (nslookup). The resolver will query the domain server for the correct ip address, if it is found then the ip address is passed to the PC. The PC will direct the data packets using the ip address.
HTTP is responsible for reliable transmission for web data from one end to another. It is achieved by means of POST and GET requests to the web server.
SMTP is used to send and forward mail information. MUA is your email software while MTA is used as a forwarder to forward email information to the right email server. The MDA is used to store your email on the server before it is transferred to the MUA. The MUA will retrieve email from the MDA using POP.
Telnet is used to create remote access to a particular device. The transmission is using in plaintext and is not secure. Nowadays, we used SSH (secure shell) to perform remote access.
SMB (Server Message Block) is a protocol which is used for folder and file sharing over the network. It is used mainly for Microsoft Windows. It follows a server and client model
Gnutella, on the other hand, is a protocol for folder and file sharing over the network using the peer networking model. It is used by bearshare and limewire. There is another protocol known as BitTorrent which is also peer to peer.
DHCP is used for dynamic assignment of ip addreses to clients. The four main messages in a DHCP exchange are DHCPDISCOVER, DHCPOFFER, DHCPREQUEST, DHCPACK. For a large enterprise network, having DHCP will remove a lot of manual work needed to configure ip addresses.
Need to remember the port numbers.
Chapter 3 slides uploaded
Hello ! The presentation slides for Chapter 3 are as follows:
Summary Slides (Beginner)
https://www.dropbox.com/s/pfxaqdho8i3tgq5/Chapter_3_Overview.ppt
Slightly Detailed Slides (Intermediate)
https://www.dropbox.com/s/w03urxvmxfuh3m8/Expl_NetFund_chapter_03_App_Layer.ppt
Detailed Slides (Advanced)
http://ibizzone.ite.edu.sg/elearning/mod/resource/view.php?id=1292
Quiz
http://ibizzone.ite.edu.sg/elearning/mod/quiz/view.php?id=1301
Follow your skill level and go through the slides. If you feel comfortable, go through the higher level slides as well and finally, attempt the quiz
Summary Slides (Beginner)
https://www.dropbox.com/s/pfxaqdho8i3tgq5/Chapter_3_Overview.ppt
Slightly Detailed Slides (Intermediate)
https://www.dropbox.com/s/w03urxvmxfuh3m8/Expl_NetFund_chapter_03_App_Layer.ppt
Detailed Slides (Advanced)
http://ibizzone.ite.edu.sg/elearning/mod/resource/view.php?id=1292
Quiz
http://ibizzone.ite.edu.sg/elearning/mod/quiz/view.php?id=1301
Follow your skill level and go through the slides. If you feel comfortable, go through the higher level slides as well and finally, attempt the quiz
Wednesday, 18 July 2012
Important points for Chapter 2
THIS IS AN IMPORTANT CHAPTER. PLEASE READ UP.
1) Distance = mm, cm, m, km (unit of measure)
Networking = Data, Segment, Packet, Frame, Signal (unit of measure or Protocol Data Unit (PDU)
2) Typical structure
preamble + source mac address + dest mac address + source ip address + dest ip address + source port + dest port + data
3) Data + Ports = Segment
Segment + IP addresses = Packet
Packet + Mac addresses = Frame
Frame + Preamble or Synchronization bits = Signal
4) End users use data to make decisions
End devices use ports (inside segments) to transfer data to the correct applications
Routers use IP addresses (inside packets) to route packets to the right network
Switches use Mac address (inside frames) to forward frames
Repeaters/hubs boost signals
5) Routers and switches has multiple ports and hence, multiple IP and Mac addresses
PC has only one NIC card and therefore, only one IP and one Mac addresses
6) Information is transmitted in chunks over the internet so that multiple devices can use the internet at the same time. This process is known as multiplexing.
7) Role of an end device is to create data, send and receive data within the network. Example of end devices are PC/laptop/servers. They are mainly classified as servers and clients. Clients send requests to servers. Servers process requests from clients and send replies back to clients.
8) Role of an intermediary device to ensure smooth data flow by transferring data from one point to another. They are the middlemen in the network. Examples are routers/switches/hubs/repeaters.
9) By having a common protocol between different networks (such as WiFi, Internet, 3G), devices can communicate with one another seamlessly. This process is transparent to the users. It is like using English in different countries (USA, Australia, Korea, Malaysia, Indonesia, Thailand). Different people can communicate if they understand the same language.
10) Recall OSI model has 7 layers (Application, Presentation, Session, Transport, Network, Datalink and Physical). This is a textbook model called reference model. OSI model is the mother of all models.
Application - Data
Presentation - JPG, HTML, MPEG
Session - Duplex, Half duplex and Simplex transmission
Transport - Segments containing ports
Network - Packets containing IP addresses
Datalink - Frames containing Mac addresses
Physical - Signals with preamble
11) Recall TCP/IP model has 4 layers (Application, Transport, Internet and Network Access). This is a working model called protocol model.
Application - Data
Transport - Segments containing ports
Internet - Packets containing IP addresses
Network Access - Frames containing Mac addresses
12) For 2 devices to communicate with each other, they have to adopt the same model (such as TCP/IP model)
1) Distance = mm, cm, m, km (unit of measure)
Networking = Data, Segment, Packet, Frame, Signal (unit of measure or Protocol Data Unit (PDU)
2) Typical structure
preamble + source mac address + dest mac address + source ip address + dest ip address + source port + dest port + data
3) Data + Ports = Segment
Segment + IP addresses = Packet
Packet + Mac addresses = Frame
Frame + Preamble or Synchronization bits = Signal
4) End users use data to make decisions
End devices use ports (inside segments) to transfer data to the correct applications
Routers use IP addresses (inside packets) to route packets to the right network
Switches use Mac address (inside frames) to forward frames
Repeaters/hubs boost signals
5) Routers and switches has multiple ports and hence, multiple IP and Mac addresses
PC has only one NIC card and therefore, only one IP and one Mac addresses
6) Information is transmitted in chunks over the internet so that multiple devices can use the internet at the same time. This process is known as multiplexing.
7) Role of an end device is to create data, send and receive data within the network. Example of end devices are PC/laptop/servers. They are mainly classified as servers and clients. Clients send requests to servers. Servers process requests from clients and send replies back to clients.
8) Role of an intermediary device to ensure smooth data flow by transferring data from one point to another. They are the middlemen in the network. Examples are routers/switches/hubs/repeaters.
9) By having a common protocol between different networks (such as WiFi, Internet, 3G), devices can communicate with one another seamlessly. This process is transparent to the users. It is like using English in different countries (USA, Australia, Korea, Malaysia, Indonesia, Thailand). Different people can communicate if they understand the same language.
10) Recall OSI model has 7 layers (Application, Presentation, Session, Transport, Network, Datalink and Physical). This is a textbook model called reference model. OSI model is the mother of all models.
Application - Data
Presentation - JPG, HTML, MPEG
Session - Duplex, Half duplex and Simplex transmission
Transport - Segments containing ports
Network - Packets containing IP addresses
Datalink - Frames containing Mac addresses
Physical - Signals with preamble
11) Recall TCP/IP model has 4 layers (Application, Transport, Internet and Network Access). This is a working model called protocol model.
Application - Data
Transport - Segments containing ports
Internet - Packets containing IP addresses
Network Access - Frames containing Mac addresses
12) For 2 devices to communicate with each other, they have to adopt the same model (such as TCP/IP model)
Important points for Chapter 1
1) The function of a router is to connect different LANs and WANs together, providing the best paths to these networks. The function of a switch is to connect multiple end devices together within the same LAN. The function of a hub is the same as the switch but it is a slower version of a switch. The function of a repeater is to boost up the signals over large distances. The function of end devices (PCs, laptop and mobile phones) is to create data, send and receive them.
2) Serial cables are used to connect WANs and they are used only by routers. Ethernet cables are used to connect LANs and they are used by all devices.
3) 3 types of ethernet cables - Straight through, crossover and rollover cables
Same devices use crossover cables to connect
Different devices use straight through cables to connect
Special case : Router to PC, Switch to Hub uses crossover cables although they are different devices.
4) WAN - covers wide geographical distance and use only serial cables
LAN - covers small geographical distance and use only ethernet cables
5) 4 elements of a network
Devices (Routers, Switches, Hubs and End devices), Medium (Ethernet cables and serial cables), Messages (Data, Segment, Packet, Frame) , Rules (TCP and UDP protocols)
6) 4 characteristics of a network
Fault tolerance, Scalability, Quality of Service and Security
7) We also go through how to use packet tracer (how to connect the devices, setting the PC ip addresses)
2) Serial cables are used to connect WANs and they are used only by routers. Ethernet cables are used to connect LANs and they are used by all devices.
3) 3 types of ethernet cables - Straight through, crossover and rollover cables
Same devices use crossover cables to connect
Different devices use straight through cables to connect
Special case : Router to PC, Switch to Hub uses crossover cables although they are different devices.
4) WAN - covers wide geographical distance and use only serial cables
LAN - covers small geographical distance and use only ethernet cables
5) 4 elements of a network
Devices (Routers, Switches, Hubs and End devices), Medium (Ethernet cables and serial cables), Messages (Data, Segment, Packet, Frame) , Rules (TCP and UDP protocols)
6) 4 characteristics of a network
Fault tolerance, Scalability, Quality of Service and Security
7) We also go through how to use packet tracer (how to connect the devices, setting the PC ip addresses)
Summary of different modes and hostname/password commands
REMEMBER YOU MUST BE IN THE RIGHT MODES TO EXECUTE THE RIGHT COMMANDS.
For NWF, there are 3 main modes for now
User mode (denoted by the ">" sign)
Router>
Priviledged mode (denoted by the "#" sign)
Router> enable
Router#
Global config mode (denoted by the "(config)#")
Router# configure terminal or conf t (short form)
Router (config)#
To return to the previous mode, type exit
For example, to return to user mode from global config mode, use the following
Router (config)# exit
Router# exit
Router >
There are 4 passwords you will need to configure in the router.
1) Console password - The password you used when you first log in to the router. There is only one console session which is numbered "0"
router(config)# line console 0
router(config)# password XXX
router(config)# login
Remember to type login to activate the password
2) Enable password - The PLAINTEXT password you used after you type "enable"
router(config)# enable password XXX
3) Enable password - The ENCRYPTED password you used after you type "enable". Cisco router will use it instead of the PLAINTEXT password.
router(config)# enable secret XXX
4) Telnet password - The password you used when you telnet into the router (seldom used in NWF). There are 5 telnet sessions supported, which are numbered from "0" to "4".
router(config)# line vty 0 4
router(config)# password XXX
router(config)# login
Remember to type login to activate the password
To configure hostname, use the command
router (config)# hostname XXX
Knowing all these will help you score good grades in the semester later on.
Tuesday, 17 July 2012
Practice Lab 1
https://www.dropbox.com/s/x5n1octvnpi26o5/Practice%20Lab%201.pkt
This is the practice lab for today. You are required to connect the devices together according to the stated ports. You need to set the hostname and passwords for the fresh router. In addition, you need to change the hostname and passwords for the preconfigured router.
Monday, 16 July 2012
Chapter 2 slides uploaded
Hello ! The presentation slides for Chapter 2 are as follows:
Summary Slides (Beginner)
https://www.dropbox.com/s/vfhkzz7wct3k4mn/Chapter_2_Overview.ppt
Slightly Detailed Slides (Intermediate)
https://www.dropbox.com/s/sv5dnuj28faoeki/Expl_NetFund_chapter_02_Comm.ppt
Detailed Slides (Advanced)
http://ibizzone.ite.edu.sg/elearning/mod/resource/view.php?id=1257
Quiz
http://ibizzone.ite.edu.sg/elearning/mod/quiz/view.php?id=1258
Follow your skill level and go through the slides. If you feel comfortable, go through the higher level slides as well and finally, attempt the quiz
Summary Slides (Beginner)
https://www.dropbox.com/s/vfhkzz7wct3k4mn/Chapter_2_Overview.ppt
Slightly Detailed Slides (Intermediate)
https://www.dropbox.com/s/sv5dnuj28faoeki/Expl_NetFund_chapter_02_Comm.ppt
Detailed Slides (Advanced)
http://ibizzone.ite.edu.sg/elearning/mod/resource/view.php?id=1257
Quiz
http://ibizzone.ite.edu.sg/elearning/mod/quiz/view.php?id=1258
Follow your skill level and go through the slides. If you feel comfortable, go through the higher level slides as well and finally, attempt the quiz
Chapter 1 slides uploaded
Hello ! The presentation slides for Chapter 1 are as follows:
Summary Slides (Beginner)
https://www.dropbox.com/s/p33afn50vsrarcq/Chapter_1_Overview.ppt
Slightly Detailed Slides (Intermediate)
https://www.dropbox.com/s/rmzjzvq1y5s55ej/Expl_NetFund_chapter_01_Intro.ppt
Detailed Slides (Advanced)
http://ibizzone.ite.edu.sg/elearning/mod/resource/view.php?id=1256
Follow your skill level and go through the slides. If you feel comfortable, go through the higher level slides as well and finally, attempt the quiz
Summary Slides (Beginner)
https://www.dropbox.com/s/p33afn50vsrarcq/Chapter_1_Overview.ppt
Slightly Detailed Slides (Intermediate)
https://www.dropbox.com/s/rmzjzvq1y5s55ej/Expl_NetFund_chapter_01_Intro.ppt
Detailed Slides (Advanced)
http://ibizzone.ite.edu.sg/elearning/mod/resource/view.php?id=1256
Follow your skill level and go through the slides. If you feel comfortable, go through the higher level slides as well and finally, attempt the quiz
Welcome PL1201B to Networking Fundamentals !
Hi PL1201B, all materials pertaining to IT2020PA Networking Fundamentals will be posted here
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