IT2203 Routing Fundamentals: Data Encapsulation

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Questions and Answers

What is the main function of a routing device in a network?

To forward packets to a destination subnet based on routes (correct)

To modify the source IP address of packets

To filter packets based on destination addresses

To block packets from reaching their destination

What does a route contain according to the routing table?

Destination subnet, mask, outbound interface, and next hop (correct)

Source IP address and packet size

Sender and receiver email addresses

Packet priority and protocol type

What is the process of selecting paths on a network along which packets are sent from a source to a destination?

Routing (correct)

Packet filtering

Network topology

Packet switching

What is the purpose of a routing table in a router?

To store routing information for packet forwarding Signup and view all the answers

What is the role of a router in packet forwarding?

To select the best path for packet forwarding Signup and view all the answers

What is the purpose of the destination address in packet routing?

To select the next-hop address for packet forwarding Signup and view all the answers

What is the process of adding a new string of information to an existing unit to form a new unit of information called?

Encapsulation Signup and view all the answers

What is the term for the reverse process of encapsulation?

Decapsulation Signup and view all the answers

What is the format of a packet in a network?

Header+Data Payload+Tail Signup and view all the answers

What is the term for the information segment added before the data payload during packet assembly?

Header Signup and view all the answers

What is a specific block of information transferred over a network called?

Protocol Data Unit (PDU) Signup and view all the answers

In a hierarchical communication process, what can the data unit transmitted from the upper layer to the lower layer be called?

Data Payload of the lower layer Signup and view all the answers

What is the primary purpose of packet forwarding?

To specify the destination subnet and forwarding path Signup and view all the answers

What is the term for the way a packet is handled by the underlying physical networks under the control of the network layer?

Packet Delivery Signup and view all the answers

What occurs when a packet is forwarded to an intermediate node because the final destination is not on a directly attached network?

Indirect Delivery Signup and view all the answers

What does a router use to forward IP packets?

Routes in the IP routing table Signup and view all the answers

What is the purpose of the routing table in a router?

To determine which router network interface or port to send information to a particular network segment Signup and view all the answers

What can be determined from the destination address and mask of a specific route?

The IP address of the subnet to which the host or router belongs Signup and view all the answers

What protocol is used to obtain the physical address of a node from a specific IP number?

ARP Signup and view all the answers

Which protocol is used for data transfer across a serial line?

PPP Signup and view all the answers

What is the primary function of Proxy ARP?

To allow a network terminal to pass data from one segment to another without changing its IP address Signup and view all the answers

What type of delivery system is Ethernet?

Best-effort delivery system Signup and view all the answers

What is the primary purpose of RARP?

To find the Internet address of a host given its physical address Signup and view all the answers

What is the characteristic of ATM that makes it suitable for text, audio, and video data transfer?

High data rates and equalsized packets/cells Signup and view all the answers

What is the primary function of the Preference value in a routing table?

To compare routes from different routing protocols Signup and view all the answers

What is the purpose of the Cost value in a routing table?

To determine the optimal route when multiple routes have the same preference Signup and view all the answers

What is the function of the Next Hop value in a routing table?

To indicate the local router's next-hop address Signup and view all the answers

What command is used to check the IP routing table?

display ip routing-table Signup and view all the answers

What is the default preference value for a static route?

60 Signup and view all the answers

What happens when a computer constructs IP packets to be sent out at the network layer?

It searches the routing table for matching destination addresses Signup and view all the answers

Study Notes

Address Resolution Protocol (ARP)

Obtains the physical address of a node from a specific IP number
Dynamically binds a high-level IP address to a low-level physical hardware address
Limited to networks that support hardware broadcast

Reverse Address Resolution Protocol (RARP)

Allows a host with no local permanent data storage media to find its Internet address given its physical address

Common Network Access Layer Protocols

Ethernet: a family of LANs, covered by IEEE 802.3 standards, uses a CSMA/CD access method
Point-to-Point Protocol (PPP): used for data transfer across a serial line
Fiber Distributed Data Interface (FDDI): a set of ANSI protocols for sending digital data over fiber optic cable
Asynchronous Transfer Mode (ATM): a wide area protocol with high data rates and equal-sized packets/cells
Frame Relay: a WAN protocol for LAN internetworking, provides fast and efficient method of transmitting information
Proxy ARP: used when a network terminal needs to pass data from one segment to another without changing its current IP address information

Packet Forwarding and Delivery

Packet forwarding: passing or moving of information between interfaces according to "directions"
Packet delivery: the way a packet is handled by the underlying physical networks
Direct delivery: occurs when the IP node forwards a packet to its final destination in the network
Indirect delivery: occurs when the IP node forwards a packet to an intermediate node (IP router) because the final destination is not on a directly attached network

Routing Table

A database that contains information about which router network interface or port to place information to send it to a particular network segment
Destination/Mask: indicates the destination network address and mask of a specific route
Example: destination address is 1.1.1.1 and the mask is 255.255.255.0, the IP address of the subnet to which the host or router belongs is 1.1.1.0

Routing Fundamentals

Routing: the process of selecting paths on a network along which packets are sent from a source to a destination
Path determination: enables a router to compare the destination address to the available routes in its routing table and to select the best path
Routes: the path information used to guide packet forwarding
Routing device (Router): a network device that forwards packets to a destination subnet based on routes
Routing table: stores routing information

Route Components

Destination: identifies a destination subnet
Mask: identifies a subnet together with a destination IP address
Outbound interface: indicates the interface through which a data packet is sent out of the local router
Next hop: indicates the next-hop address used by the router to forward the data packet to the destination subnet

Data Encapsulation and Decapsulation

Encapsulation: a process wherein a new string of information is added to an existing unit to form a new unit of information
Decapsulation: the reverse process of encapsulation, wherein the header and tail of a packet are removed to obtain the data payload

TCP Protocol Data Units

Protocol Data Unit (PDU): a specific block of information transferred over a network
Protocol (Proto): indicates the protocol type of the route
Preference (Pre): indicates the routing protocol preference of the route
Cost: indicates the cost of the route
Next Hop: indicates the local router’s next-hop address of the route to the destination network
Interface: indicates the outbound interface of the route

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Description

This quiz covers the concepts of data encapsulation and decapsulation in network communication, including the process of adding headers and trailers to form a new unit of information.