Nt1310 Unit 7
Name: Date: Northampton Community College
CISC 231 – Data Communications and LANs (CCNA 1) STUDY GUIDE FOR CHAPTER 2
1. What is the purpose of a network protocol?
A network protocol defines rules and conventions for communication between network devices. Protocols for computer networking all generally use packet switching techniques to send and receive messages in the form of packets.
2. Define the role of an intermediary device in the network.
Communication to run smoothly across the network there are devices that place intermediary roles in networking. These intermediary devices provide connectivity and work behind the scenes to ensure that data flows across the network. These devices connect the individual hosts (end devices) to the network and can connect multiple individual networks to form an internetwork. …show more content…
Most intermediary devices use an IP address, in conjunction with information about the network interconnections, to determine best path that messages take through the network.
3. Define the role of an end device in the network.
The network devices that people are most familiar with are called end devices. These devices form the interface between the human network and the underlying communication network. They usually refer to a piece of equipment that is either the source or the destination of a message on a network.
4. What is encapsulation?
Encapsulation is an attribute of object design. It means that all of the object's data is contained and hidden in the object and access to it restricted to members of that class. A procedure is a type of encapsulation because it combines a series of computer instructions. Likewise, a complex data type, such as a record or class, relies on encapsulation.
5. What are the seven layers of the OSI model (in order)? What is the role of each layer?
7. Application
6. Presentation
5. Session
4. Transport
3.
Network
2. Data Link
1. Physical
7. Application Layer
The Application layer, also called Layer 7, is the highest layer in the OSI model. It contains applications that facilitate network communication. These are not applications like Microsoft Word or Excel, but rather application protocols such as Hypertext Transfer Protocol (HTTP) for browsing the World Wide Web or File Transfer Protocol (FTP) for transferring files on net-works and over the Web. At the Application layer, the data still resembles something that people can read and interpret.
6. Presentation Layer
At the Presentation layer (Layer 6) data is first converted into a form that can be sent over a network. At this layer data is compressed and decompressed and encrypted or decrypted, depending on which direction it's traveling. You can think of the Presentation layer as the "translation layer."
5. Session Layer
The Session layer (Layer 5) is responsible for establishing, synchronizing, maintaining, and then terminating the sessions between computers. It also handles error detection and notification. You can think of the Session layer as the "traffic cop" that directs the network traffic and lets the appropriate traffic flow at the appropriate time.
4. Transport Layer
The Transport layer (Layer 4) handles the actual processing of data between devices. This layer is responsible for resending any packets that do not receive an acknowledgment from the destination address. It's also responsible for any problems that are associated with fragmentation of packets.
3. Network Layer
The Network layer (Layer 3) is responsible for providing the mechanism by which data can be moved from computer to computer or from network to network. The Network layer does not actually move the data; instead it provides the addressing information and route discovery that are necessary to move the data to the appropriate location. The Network layer contains many protocols that facilitate these services, including Internet Protocol (IP), Internet Control Message Protocol (ICMP), Internet Group Management Protocol (IGMP), and Address Resolution Protocol (ARP).
2. Data Link Layer
The Data Link layer (Layer 2) is responsible for sending data to the Physical layer so that it can be put onto the "wire" or network media. The Data Link layer is subdivided into two other layers: the Logical Link Control (LLC) and the Media Access Control (MAC) layers. The LLC connects the Data Link layer to the higher-level protocols such as IP at the Network layer. The MAC layer connects the Data Link layer to the physical connection and provides the MAC address. The Data Link layer also defines the technology that is used for the network. This layer can also perform checksums, which are calculations that the system uses to make sure that packets are not damaged in transit.
1. Physical Layer
The Physical layer (Layer 1) defines the physical characteristics of the network such as the type of cable that must be used as well as the voltage that will be used to transmit data through the network. Since the Physical layer defines these characteristics, it also establishes the topology of the network. Many standards are defined at this layer, such as the IEEE 802.3 standard for Ethernet as well as the IEEE 802.5 standard for Token Ring networks.
6. Compare the OSI model to the TCP/IP model.
There are seven layers in the OSI Model, only four in the TCP/IP model. This is because TCP/IP assumes that applications will take care of everything beyond the Transport layer. The TCP/IP model also squashes the OSI's Physical and Data Link layers together into the Network Access Layer. Internet Protocol really doesn't (and shouldn't) care about the hardware underneath, so long as the computer can run the network device and send IP packets over the connection.
7. What is the frame trailer for at layer 2?
The trailer indicates the frame check sequence number. It is used for error correction.
8. What is a PDU?
(Protocol Data Unit), Information that is delivered as a unit among peer entities of a network and that may contain control information, such as address information, or user data. In a layered system, a unit of data which is specified in a protocol of a given layer and which consists of protocol-control information and possibly user data of that layer. For example: Bridge PDU or iSCSI PDU.
9. Describe a LAN.
A local area network (LAN) supplies networking capability to a group of computers in close proximity to each other such as in an office building, a school, or a home. A LAN is useful for sharing resources like files, printers, games or other applications. A LAN in turn often connects to other LANs, and to the Internet or other WAN. Most local area networks are built with relatively inexpensive hardware such as Ethernet cables, network adapters, and hubs. Wireless LAN and other more advanced LAN hardware options also exist. Specialized operating system software may be used to configure a local area network.
10. What is the difference between a LAN and a WAN?
While LAN and WAN are both two branches of networking and share many similarities, there’s a very fine line between them as well. There are differences on the basis of scope and connections. A WAN was typically over a large geographical area, like a huge private network (mini internet)
WAN is considered to be more vast and widespread. WAN is meant for networking between wide geographical regions like between two cities or even across different time zones while LAN is mainly used for private connectivity among residential offices or a single edifice. Hence a small scale WAN can be developed by creating many LANs. In case of LAN, Ethernet is the main device which is used for connecting the workstations or the computers. Ethernet is a bus based protocol device in which cables and wires and permanent. Ethernet helps is the interconnection of the different types of LANs. While in the case of WAN, common carriers are usually used and most people opt in for service providers. When it comes to the speed of both the network technologies, a LAN is usually faster as it is confined to a small space with servers in a nearby location.
11. What is multiplexing?
Multiplexing is the process of transmitting several different signals or information streams via a single carrier. The transmission of all these signals or streams takes place simultaneously by combining the several signals into one common signal that will efficiently moves through the carrier bandwidth. Once the signal reaches the destination point for one of the transmissions, that integrated signal re-assimilates into its original form and is received.
12. How are port numbers used in the Transport layer PDU?
Ports can provide multiple endpoints on a single node. For example, the name on a postal address is a kind of multiplexing, and distinguishes between different recipients of the same location. Computer applications will each listen for information on their own ports, which enables the use of more than one network service at the same time.
The UDP client process randomly selects a port number from the dynamic range of port numbers and uses this as the source port for the conversation. The destination port will usually be the Well Known or Registered port number assigned to the server process. The client software must know what port number is associated with the server process on the remote host. This destination port number is configured, either by default or manually. For example, when a web browser application makes a request to a web server, the browser uses TCP and port number 80 unless otherwise specified. This is because TCP port 80 is the default port assigned to web-serving applications. Many common applications have default port assignments.
Well Known Ports (Numbers 0 to 1023) - These numbers are reserved for services and applications. They are commonly used for applications such as HTTP (web server) POP3/SMTP (e-mail server) and Telnet. By defining these well-known ports for server applications, client applications can be programmed to request a connection to that specific port and its associated service.
Registered Ports (Numbers 1024 to 49151) - These port numbers are assigned to user processes or applications. These processes are primarily individual applications that a user has chosen to install rather than common applications that would receive a Well Known Port. When not used for a server resource, these ports may also be used dynamically selected by a client as its source port.
Dynamic or Private Ports (Numbers 49152 to 65535) - Also known as Ephemeral Ports, these are usually assigned dynamically to client applications when initiating a connection. It is not very common for a client to connect to a service using a Dynamic or Private Port (although some peer-to-peer file sharing programs do).
Using both TCP and UDP
Some applications may use both TCP and UDP. For example, the low overhead of UDP enables DNS to serve many client requests very quickly. Sometimes, however, sending the requested information may require the reliability of TCP. In this case, the well known port number of 53 is used by both protocols with this service.
13. Which layer encapsulates the segment into packets?
Transport layer, layer 4
14. What is the Layer 4 PDU called?
Segments
15. What is the Layer 3 PDU called?
Packets
16. What is the Layer 2 PDU called?
Frames
17. At what layer do bridges and switches function?
The session layer, layer 2
18. What is the difference between a bridge and a switch?
One of the main differences is that bridges do their jobs using processors, so they are slower than switches, which use ASICs. The other is regarding number of ports. ASIC is electronics dedicated to particular functions, so you will sometimes hear about "wire speed" when we are talking about switches, which means that things work as if we had nothing there, the switch would not affect the transmission speed, it is as if just a cable were in place. Sometimes a switch is called a multiport bridge, as if a switch is just a box with many bridges in that, switching is kind of doing bridging, but faster.
19. What do bridges and switches use to make switching decisions?
A switch uses the MAC address to make forwarding decisions. Switches use a MAC address table that stores the MAC address it has learned and the ports that they were learned from. When a packet comes into a switch the switch looks at the destination MAC address then looks up that address in the MAC Address Table to get the port to send the packet to.
20. At what layer do routers function?
Layer 3, Networking layer
21. What is a router?
A router is a networking device that forwards data from one network to another. This includes residential routers that also use Network Address Translation. They take information that arrives through your broadband signal via a modem, decipher it, and deliver it to your computer. The router will also choose the best route for the data packet so that you receive the information quickly.
22. What do we mean when we talk about the “Internet Cloud”? In science, cloud computing is a synonym for distributed computing over a network and means the ability to run a program on many connected computers at the same time. The phrase is also, more commonly used to refer to network-based services which appear to be provided by real server hardware, which in fact are served up by virtual hardware, simulated by software running on one or more real machines. Such virtual servers do not physically exist and can therefore be moved around and scaled up (or down) on the fly without affecting the end user - arguably, rather like a cloud.
“The Internet cloud, where the distributed and programmable network of services across the globe will serve all the data, resources and functionality we will ever use.”
23. What is a transceiver and what does it do?
A transceiver is a device which combines transmission and reception capability on shared circuitry. There are a number of different types of transceivers designed for an assortment of uses, and the transceiver is the cornerstone of wireless communication. One common example of a transceiver is a cellular phone, which is capable of sending and receiving data, unlike a basic radio, which can only receive signals.
Transceivers can be divided into two rough categories; full and half duplex. In a full duplex transceiver, the device can transmit and receive at the same time. Cell phones are, again, an excellent example of a full duplex transceiver, as both parties can talk at once. By contrast, a half duplex transceiver silences one party while the other transmits. Many radio systems operate on a half duplex method, which is why people signal when they are going “out,” alerting the other user to the fact that the frequency is open for transmission.
CISC 231 – Data Communications and LANs (CCNA 1) STUDY GUIDE FOR CHAPTER 2
1. What is the purpose of a network protocol?
A network protocol defines rules and conventions for communication between network devices. Protocols for computer networking all generally use packet switching techniques to send and receive messages in the form of packets.
2. Define the role of an intermediary device in the network.
Communication to run smoothly across the network there are devices that place intermediary roles in networking. These intermediary devices provide connectivity and work behind the scenes to ensure that data flows across the network. These devices connect the individual hosts (end devices) to the network and can connect multiple individual networks to form an internetwork. …show more content…
Most intermediary devices use an IP address, in conjunction with information about the network interconnections, to determine best path that messages take through the network.
3. Define the role of an end device in the network.
The network devices that people are most familiar with are called end devices. These devices form the interface between the human network and the underlying communication network. They usually refer to a piece of equipment that is either the source or the destination of a message on a network.
4. What is encapsulation?
Encapsulation is an attribute of object design. It means that all of the object's data is contained and hidden in the object and access to it restricted to members of that class. A procedure is a type of encapsulation because it combines a series of computer instructions. Likewise, a complex data type, such as a record or class, relies on encapsulation.
5. What are the seven layers of the OSI model (in order)? What is the role of each layer?
7. Application
6. Presentation
5. Session
4. Transport
3.
Network
2. Data Link
1. Physical
7. Application Layer
The Application layer, also called Layer 7, is the highest layer in the OSI model. It contains applications that facilitate network communication. These are not applications like Microsoft Word or Excel, but rather application protocols such as Hypertext Transfer Protocol (HTTP) for browsing the World Wide Web or File Transfer Protocol (FTP) for transferring files on net-works and over the Web. At the Application layer, the data still resembles something that people can read and interpret.
6. Presentation Layer
At the Presentation layer (Layer 6) data is first converted into a form that can be sent over a network. At this layer data is compressed and decompressed and encrypted or decrypted, depending on which direction it's traveling. You can think of the Presentation layer as the "translation layer."
5. Session Layer
The Session layer (Layer 5) is responsible for establishing, synchronizing, maintaining, and then terminating the sessions between computers. It also handles error detection and notification. You can think of the Session layer as the "traffic cop" that directs the network traffic and lets the appropriate traffic flow at the appropriate time.
4. Transport Layer
The Transport layer (Layer 4) handles the actual processing of data between devices. This layer is responsible for resending any packets that do not receive an acknowledgment from the destination address. It's also responsible for any problems that are associated with fragmentation of packets.
3. Network Layer
The Network layer (Layer 3) is responsible for providing the mechanism by which data can be moved from computer to computer or from network to network. The Network layer does not actually move the data; instead it provides the addressing information and route discovery that are necessary to move the data to the appropriate location. The Network layer contains many protocols that facilitate these services, including Internet Protocol (IP), Internet Control Message Protocol (ICMP), Internet Group Management Protocol (IGMP), and Address Resolution Protocol (ARP).
2. Data Link Layer
The Data Link layer (Layer 2) is responsible for sending data to the Physical layer so that it can be put onto the "wire" or network media. The Data Link layer is subdivided into two other layers: the Logical Link Control (LLC) and the Media Access Control (MAC) layers. The LLC connects the Data Link layer to the higher-level protocols such as IP at the Network layer. The MAC layer connects the Data Link layer to the physical connection and provides the MAC address. The Data Link layer also defines the technology that is used for the network. This layer can also perform checksums, which are calculations that the system uses to make sure that packets are not damaged in transit.
1. Physical Layer
The Physical layer (Layer 1) defines the physical characteristics of the network such as the type of cable that must be used as well as the voltage that will be used to transmit data through the network. Since the Physical layer defines these characteristics, it also establishes the topology of the network. Many standards are defined at this layer, such as the IEEE 802.3 standard for Ethernet as well as the IEEE 802.5 standard for Token Ring networks.
6. Compare the OSI model to the TCP/IP model.
There are seven layers in the OSI Model, only four in the TCP/IP model. This is because TCP/IP assumes that applications will take care of everything beyond the Transport layer. The TCP/IP model also squashes the OSI's Physical and Data Link layers together into the Network Access Layer. Internet Protocol really doesn't (and shouldn't) care about the hardware underneath, so long as the computer can run the network device and send IP packets over the connection.
7. What is the frame trailer for at layer 2?
The trailer indicates the frame check sequence number. It is used for error correction.
8. What is a PDU?
(Protocol Data Unit), Information that is delivered as a unit among peer entities of a network and that may contain control information, such as address information, or user data. In a layered system, a unit of data which is specified in a protocol of a given layer and which consists of protocol-control information and possibly user data of that layer. For example: Bridge PDU or iSCSI PDU.
9. Describe a LAN.
A local area network (LAN) supplies networking capability to a group of computers in close proximity to each other such as in an office building, a school, or a home. A LAN is useful for sharing resources like files, printers, games or other applications. A LAN in turn often connects to other LANs, and to the Internet or other WAN. Most local area networks are built with relatively inexpensive hardware such as Ethernet cables, network adapters, and hubs. Wireless LAN and other more advanced LAN hardware options also exist. Specialized operating system software may be used to configure a local area network.
10. What is the difference between a LAN and a WAN?
While LAN and WAN are both two branches of networking and share many similarities, there’s a very fine line between them as well. There are differences on the basis of scope and connections. A WAN was typically over a large geographical area, like a huge private network (mini internet)
WAN is considered to be more vast and widespread. WAN is meant for networking between wide geographical regions like between two cities or even across different time zones while LAN is mainly used for private connectivity among residential offices or a single edifice. Hence a small scale WAN can be developed by creating many LANs. In case of LAN, Ethernet is the main device which is used for connecting the workstations or the computers. Ethernet is a bus based protocol device in which cables and wires and permanent. Ethernet helps is the interconnection of the different types of LANs. While in the case of WAN, common carriers are usually used and most people opt in for service providers. When it comes to the speed of both the network technologies, a LAN is usually faster as it is confined to a small space with servers in a nearby location.
11. What is multiplexing?
Multiplexing is the process of transmitting several different signals or information streams via a single carrier. The transmission of all these signals or streams takes place simultaneously by combining the several signals into one common signal that will efficiently moves through the carrier bandwidth. Once the signal reaches the destination point for one of the transmissions, that integrated signal re-assimilates into its original form and is received.
12. How are port numbers used in the Transport layer PDU?
Ports can provide multiple endpoints on a single node. For example, the name on a postal address is a kind of multiplexing, and distinguishes between different recipients of the same location. Computer applications will each listen for information on their own ports, which enables the use of more than one network service at the same time.
The UDP client process randomly selects a port number from the dynamic range of port numbers and uses this as the source port for the conversation. The destination port will usually be the Well Known or Registered port number assigned to the server process. The client software must know what port number is associated with the server process on the remote host. This destination port number is configured, either by default or manually. For example, when a web browser application makes a request to a web server, the browser uses TCP and port number 80 unless otherwise specified. This is because TCP port 80 is the default port assigned to web-serving applications. Many common applications have default port assignments.
Well Known Ports (Numbers 0 to 1023) - These numbers are reserved for services and applications. They are commonly used for applications such as HTTP (web server) POP3/SMTP (e-mail server) and Telnet. By defining these well-known ports for server applications, client applications can be programmed to request a connection to that specific port and its associated service.
Registered Ports (Numbers 1024 to 49151) - These port numbers are assigned to user processes or applications. These processes are primarily individual applications that a user has chosen to install rather than common applications that would receive a Well Known Port. When not used for a server resource, these ports may also be used dynamically selected by a client as its source port.
Dynamic or Private Ports (Numbers 49152 to 65535) - Also known as Ephemeral Ports, these are usually assigned dynamically to client applications when initiating a connection. It is not very common for a client to connect to a service using a Dynamic or Private Port (although some peer-to-peer file sharing programs do).
Using both TCP and UDP
Some applications may use both TCP and UDP. For example, the low overhead of UDP enables DNS to serve many client requests very quickly. Sometimes, however, sending the requested information may require the reliability of TCP. In this case, the well known port number of 53 is used by both protocols with this service.
13. Which layer encapsulates the segment into packets?
Transport layer, layer 4
14. What is the Layer 4 PDU called?
Segments
15. What is the Layer 3 PDU called?
Packets
16. What is the Layer 2 PDU called?
Frames
17. At what layer do bridges and switches function?
The session layer, layer 2
18. What is the difference between a bridge and a switch?
One of the main differences is that bridges do their jobs using processors, so they are slower than switches, which use ASICs. The other is regarding number of ports. ASIC is electronics dedicated to particular functions, so you will sometimes hear about "wire speed" when we are talking about switches, which means that things work as if we had nothing there, the switch would not affect the transmission speed, it is as if just a cable were in place. Sometimes a switch is called a multiport bridge, as if a switch is just a box with many bridges in that, switching is kind of doing bridging, but faster.
19. What do bridges and switches use to make switching decisions?
A switch uses the MAC address to make forwarding decisions. Switches use a MAC address table that stores the MAC address it has learned and the ports that they were learned from. When a packet comes into a switch the switch looks at the destination MAC address then looks up that address in the MAC Address Table to get the port to send the packet to.
20. At what layer do routers function?
Layer 3, Networking layer
21. What is a router?
A router is a networking device that forwards data from one network to another. This includes residential routers that also use Network Address Translation. They take information that arrives through your broadband signal via a modem, decipher it, and deliver it to your computer. The router will also choose the best route for the data packet so that you receive the information quickly.
22. What do we mean when we talk about the “Internet Cloud”? In science, cloud computing is a synonym for distributed computing over a network and means the ability to run a program on many connected computers at the same time. The phrase is also, more commonly used to refer to network-based services which appear to be provided by real server hardware, which in fact are served up by virtual hardware, simulated by software running on one or more real machines. Such virtual servers do not physically exist and can therefore be moved around and scaled up (or down) on the fly without affecting the end user - arguably, rather like a cloud.
“The Internet cloud, where the distributed and programmable network of services across the globe will serve all the data, resources and functionality we will ever use.”
23. What is a transceiver and what does it do?
A transceiver is a device which combines transmission and reception capability on shared circuitry. There are a number of different types of transceivers designed for an assortment of uses, and the transceiver is the cornerstone of wireless communication. One common example of a transceiver is a cellular phone, which is capable of sending and receiving data, unlike a basic radio, which can only receive signals.
Transceivers can be divided into two rough categories; full and half duplex. In a full duplex transceiver, the device can transmit and receive at the same time. Cell phones are, again, an excellent example of a full duplex transceiver, as both parties can talk at once. By contrast, a half duplex transceiver silences one party while the other transmits. Many radio systems operate on a half duplex method, which is why people signal when they are going “out,” alerting the other user to the fact that the frequency is open for transmission.