160 Questions
What is the primary function of the path determination function in a router?
To select the most appropriate interface for forwarding a packet
What is a prerequisite for performing routing?
Designing an addressing plan
What is the main advantage of Subnetting?
It uses a fairly simple implementation model
What is the primary reason why routing is used almost exclusively at the IP level?
To construct large networks in which heavy broadcasting or huge routing tables are not feasible
What is the main purpose of assigning addresses to network elements?
To facilitate data delivery
What is the common design plan used in IP addressing?
IP Address Classes, Subnetting, and CIDR
What is the primary function of the switching function in a router?
To accept a packet on one interface and forward it on a second interface
What is a key feature of IP addressing design?
Addresses are broken into fields corresponding to levels in a physical hierarchy
What is the most stable configuration in routing?
Static routing
What happens to the routing tables as networks grow in size?
They grow proportionately
What is the primary function of routing algorithms and protocols?
To select the least-cost path to the destination
Why is it not possible to have every router keep an entry of every other router in the network?
Due to the large size of the network
What is the consequence of forcing dynamic routing on situations that do not need it?
It is a waste of bandwidth, effort, and money
What is the purpose of assigning costs to network paths?
To select the least-cost path to the destination
What is the result of having large routing tables?
All of the above
What is the hierarchical routing approach similar to?
A telephone network
What is the primary function of a router in Figure 2?
To pass the packet to the best network along the path
What is the destination network address of the packet sent out through interface S0 of Router 1?
100.1.0.0
What is the interface through which a packet destined for network 100.4.0.0 should be sent out from Router 1?
S2
What is the role of Router 2 in Figure 2?
The next hop, or router, along the path
What is the significance of the table in Figure 2?
It shows the best network along the path for each destination network
What is the primary purpose of using network layer addresses in routing?
To determine the best path to the destination network
What is the function of the path determination function in routing?
To determine the best path to the destination network
What is the relationship between Router 1 and Router 2 in Figure 2?
Router 2 is the next hop for Router 1
What is the primary feature of a networking switch?
Speed
What is the main function of IP routing?
To send packets from a host on one network to another host on a different remote network
What is used by IP routers to determine the next-hop address?
Routing tables
What is the main difference between a normal bridge and a layer 3 switch?
Routing capabilities
What is the purpose of RAM buffers in normal bridges and routers?
To store packets temporarily
What is the advantage of using special silicon chips in switches?
Faster packet forwarding
What is the function of a layer 2 switch?
Bridge packets
What is the main characteristic of an electrical switch?
Introduces no resistance
What is the primary goal of routing in a network?
To select the best path for packet transmission
What is the trade-off between fairness and optimality in packet transmission?
Higher throughput at the cost of fairness
What is the purpose of the ARP table in a router?
To map IP addresses to MAC addresses
What is the main function of the routing table in a router?
To store routing information
What is the primary reason why routers employ two basic functions?
To relay packets from one data link to another
What is the relationship between the routing table and the ARP table in a router?
The ARP table is used to map IP addresses to routing information
What is the primary benefit of using a routing algorithm?
Improved packet transmission efficiency
What is the main consideration in designing a routing algorithm?
Keeping overhead processing required to a minimum
What is the destination network address of the packet sent out through interface S1 of Router 1?
100.2.0.0
Which interface should a packet destined for network 100.3.0.0 be sent out from Router 1?
S2
What is the primary function of Router 1 in Figure 2?
To pass packets to the best network along the path
What is the role of the table in Figure 2?
To show the relationship between routers and networks
What is the primary benefit of using network layer addresses in routing?
To enable hierarchical routing
What is the primary function of Router 2 in Figure 2?
To act as the next hop along the path
What happens when a packet destined for network 100.1.0.0 arrives at Router 1?
Router 1 sends the packet out through interface S0
What is the primary goal of routing in a network?
To forward packets to their final destination
What is the main disadvantage of dynamic routing?
It consumes a lot of bandwidth and processor time
What is the primary reason for hierarchical routing?
To make networks more scalable
What do routing algorithms and protocols determine?
The least-cost path to the destination
What happens to routing tables as networks grow?
They grow proportionately
What is the primary function of IP routing?
To determine the next-hop address and forward it
Why is static routing considered stable?
Because it is less prone to changes
What is the main difference between a normal bridge and a layer 3 switch?
A normal bridge bridges whereas a layer 3 switch routes
What is the result of having large routing tables?
Router processor time increases
What is the main advantage of hierarchical routing?
It makes networks more scalable
What is used by IP routers to determine the next-hop address?
Routing tables
What is the primary feature of a networking switch?
Speed
What is the purpose of assigning costs to network paths?
To select the least-cost path
What happens to packets in RAM buffers?
They are stored temporarily while being processed
What is the advantage of using special silicon chips in switches?
They forward packets directly from source to destination without passing through RAM buffers
What is the function of a layer 2 switch?
To bridge packets to their destination
What is an electrical switch similar to?
A wire
What is the primary goal of routing in a network?
To determine the best path for packet transmission
Why is it important to keep overhead processing to a minimum in routers?
To ensure the efficiency of the routing algorithm
What is the result of prioritizing packet transmission between adjacent stations?
Higher throughput but unfairness to distant stations
What is the role of the ARP table in a router?
To map IP addresses to MAC addresses
What is the primary function of the routing table in a router?
To determine the path for packet transmission
What is the trade-off between fairness and optimality in packet transmission?
Higher throughput but unfairness to distant stations
What is the purpose of assigning network layer addresses in routing?
To identify the source and destination of packets
What is the primary function of a router in a network?
To relay packets from one data link to another
What is the primary purpose of breaking addresses into fields corresponding to levels in a physical hierarchy?
To permit addresses to be handled in blocks
What is a common design plan used in IP addressing?
IP Address Classes and Subnetting
What is the benefit of using Subnetting in IP addressing?
It provides great flexibility with a simple implementation model
What is the main advantage of assigning addresses to network elements?
It permits routers to forward packets without broadcasting
What is the primary consideration in designing a plan for assigning addresses?
The features provided by router manufacturers
What is the purpose of extracting path information from addresses in switching nodes?
To permit routers to forward packets efficiently
What is the primary constraint in designing an addressing plan?
The features provided by router manufacturers
What is the key feature of IP addressing design?
It is hierarchical
What is the destination network address of the packet sent out through interface S0 of Router 1?
100.1.0.0
What is the purpose of the table in Figure 2?
To illustrate the network layer addresses and their corresponding ports
What is the primary function of Router 1 in Figure 2?
To route packets to their destination networks
What is the interface through which a packet destined for network 100.4.0.0 should be sent out from Router 1?
S2
What is the role of Router 2 in Figure 2?
To forward packets to the next hop
What is the primary purpose of using network layer addresses in routing?
To enable routers to forward packets to their destination networks
What happens when a packet destined for network 100.1.0.0 arrives at Router 1?
The packet is sent out through interface S0
What is the primary goal of routing in a network?
To enable routers to forward packets to their destination networks
What is the primary advantage of using a hierarchical address assignment scheme?
It enables routers to forward packets without relying on a complete listing of all possible destinations.
What is a key feature of Subnetting?
It provides great flexibility while using a fairly simple implementation model.
What is the primary purpose of breaking addresses into fields corresponding to levels in a physical hierarchy?
To facilitate data delivery by allowing addresses to be handled in blocks.
What is a common design plan used in IP addressing?
IP Address Classes
What is a prerequisite for performing routing?
A plan must exist by which addresses are assigned.
What is the primary benefit of using CIDR?
It enables routers to forward packets without relying on broadcasting.
What is the primary function of the implementation phase of routing?
To extract path information from addresses.
What is the primary benefit of using a hierarchical addressing scheme?
It enables routers to forward packets efficiently without relying on broadcasting.
What is the result of prioritizing packet transmission between adjacent stations over distant stations?
Higher throughput but unfair to distant stations
What is the primary consideration in designing a routing algorithm?
Minimizing overhead processing required
What is the function of the path determination function in a router?
To determine the next-hop address
What is the trade-off between fairness and optimality in packet transmission?
Optimality is prioritized over fairness
What is the purpose of the routing table in a router?
To determine the next-hop address for packet transmission
What is the consequence of forcing dynamic routing on situations that do not need it?
Inefficient use of network resources
What is the primary benefit of using network layer addresses in routing?
Improved routing efficiency
What is the relationship between the routing table and the ARP table in a router?
The two tables are independent of each other
What is the primary function of a router in IP routing?
To examine the destination IP address of a packet and determine the next-hop address
What is the main difference between a normal bridge and a layer 3 switch?
Normal bridges use RAM buffers, while layer 3 switches use special silicon chips
What is the primary feature of a networking switch?
Speed
What do IP routers use to determine the next-hop address?
Routing tables
What is the primary function of a layer 2 switch?
To bridge networks
What is the advantage of using special silicon chips in switches?
They can forward packets directly from source to destination without passing through RAM buffers
What is the primary goal of routing in a network?
To send packets from a host on one network to another host on a different remote network
What is the main characteristic of an electrical switch?
It introduces no resistance, no attenuation, no delay
What is the primary concern when assigning costs to network paths?
Selecting the least-cost path to the destination
What is the main disadvantage of large routing tables?
They consume processor time and bandwidth
What is the purpose of hierarchical routing?
To route packets efficiently in large networks
What is the primary benefit of using static routing?
It consumes less bandwidth and effort
What is the main reason why dynamic routing is not always necessary?
It is a waste of bandwidth, effort, and money in certain situations
What is the primary function of routing algorithms and protocols?
To determine the least-cost path to the destination
What is the main consequence of having large networks?
Routing tables grow proportionately
What is the primary advantage of using hierarchical routing?
It makes routing more efficient in large networks
What is the primary characteristic of a routed protocol?
It defines the format and use of packet fields.
What is the primary purpose of assigning addresses to network elements?
To provide network-layer addressing information.
What is the main advantage of planning for routing in new network installations?
Enabling easier addition of routers in strategic locations.
What is the primary function of a routing protocol?
To update and maintain routing tables.
What is the main difference between static and dynamic routing?
Static routing is manual, while dynamic routing is automatic.
Why is it important to centralize addressing authority in a network?
To ensure that addresses are assigned in accordance with the design plan.
What is the primary reason for using routing at the IP level?
Because it is almost always used in the Internet environment.
What is the primary concern when designing an addressing scheme for a network?
Enabling routing.
What is the main trade-off in packet transmission?
Between fairness and optimality
What is the primary goal of routing in a network?
To ensure fairness and optimality in packet transmission
What is the relationship between the routing table and the ARP table in a router?
The routing table is used to determine the ARP table entries
What is the main function of a routing algorithm?
To determine the most efficient path between two nodes
What is the main consideration in designing a routing algorithm?
Minimizing overhead processing
What is the primary benefit of using network layer addresses in routing?
To enable efficient routing of packets
What is the primary function of the routing table in a router?
To determine the next-hop address
What is the primary function of a router in a network?
To relay packets between data links
What information do addresses convey to facilitate data delivery?
Partial information about where a host is located
What is the key feature of IP addressing design that enables routers to forward packets without broadcasting?
Hierarchical structure
What is the primary benefit of using Subnetting in IP addressing?
Greater flexibility
What is a key factor in classifying adaptive algorithms?
The source of information used by the algorithm
What is the primary reason why IP routing is used almost exclusively at the IP level?
To avoid broadcasting and large routing tables
What is the primary goal of a routing algorithm when updating the routing table?
To determine the best information to include in the table
What is referred to as convergence in dynamic routing?
The consistent and accurate information about the network topology
What is the relationship between the design and implementation of IP addressing?
The implementation is limited by the design
What is the purpose of a routing protocol in dynamic routing?
To define the set of rules for router communication
What is the primary function of a router in a network?
To accept packets on one interface and forward them on another
What is the primary advantage of using hierarchical routing in large networks?
Increased scalability
What is the term used to describe the number generated by a routing algorithm for each path through the network?
Metric
What is the primary benefit of assigning addresses to network elements in a hierarchical structure?
Increased routing efficiency
What are the two basic functions that dynamic routing relies on?
Routing table maintenance and routing update distribution
What is the primary goal of a routing algorithm?
To determine the best information to include in the routing table
What is the result of all routers having consistent information about the network topology?
The network is considered to have converged
What information do routers receive from other routers connected to the same network?
Distance vector information
What is the purpose of a router adding a distance vector number to the routing table?
To increase the distance vector
What is the similar concept to distance vector information in real life?
Signs at a highway intersection
What is the process of updating routing tables in distance vector algorithms?
Step-by-step process between directly connected neighbour routers
What is the result of routers receiving information from other routers in distance vector algorithms?
Routers accumulate network distances
What is the limitation of distance vector algorithms?
They do not allow a router to know the exact topology of an internetwork
How do routers update their routing tables in distance vector algorithms?
By receiving information from other routers and adding a distance vector number
What is the purpose of distance vector algorithms?
To maintain a database of network topology information
Study Notes
IP Routing Principles
- IP Routing is a process that sends packets from a host on one network to another host on a different remote network.
- It helps examine the destination IP address of a packet, determine the next-hop address, and forward it.
Switching
- A networking switch is designed to behave like an electrical switch, directing data signals to one of several wires.
- Its primary feature is speed, and it appears like a wire when relaying data signals.
- Layer 2 switches bridge, whereas layer 3 switches route.
- Switches use special silicon chips to forward packets directly from source to destination without passing through RAM buffers.
Routing and Network Layer Addresses
- Routers relay a packet from one data link to another.
- To relay a packet, a router employs two basic functions:
- Path determination function
- Switching function
- A router knows that the packet should be sent out on a specific port based on the network portion of the address.
Routing Functions
- Path determination function: determines the best direction to send the packet out.
- Switching function: enables a router to accept a packet on one interface and forward it on a second interface.
Prerequisites for Routing
- Design: a plan must exist for assigning addresses, typically broken into fields corresponding to levels in a physical hierarchy.
- Implementation: the design plan must be implemented in switching nodes, which must be able to extract path information from the addresses.
Routing Algorithms and Protocols
- Routing algorithms and protocols form the core of the Internet.
- Network engineers assign costs to network paths, and routing protocols select the least-cost path to the destination.
Types of Routing
- Static Routing: a plan must exist by which addresses are assigned.
- Default Routing: a default route is used when a router does not know where to send a packet.
- Dynamic Routing: routers update their routing tables based on changes in the network.
Routing Updates
- Routing updates are used to inform other routers of changes in the network.
- Figure 4 illustrates dynamic routing, where routers update their routing tables based on changes in the network.
Limitations of Routing
- As networks grow in size, the routing tables also grow proportionately, consuming considerable router memory.
- The processor time is eaten up in scanning these tables and bandwidth is consumed in sending status reports about the updated routing tables.
- Ultimately, the routing has to be done hierarchically, similar to a telephone network.
IP Routing Principles
- IP Routing is a process that sends packets from a host on one network to another host on a different remote network.
- It helps examine the destination IP address of a packet, determine the next-hop address, and forward it.
Switching
- A networking switch is designed to behave like an electrical switch, directing data signals to one of several wires.
- Its primary feature is speed, and it appears like a wire when relaying data signals.
- Layer 2 switches bridge, whereas layer 3 switches route.
- Switches use special silicon chips to forward packets directly from source to destination without passing through RAM buffers.
Routing and Network Layer Addresses
- Routers relay a packet from one data link to another.
- To relay a packet, a router employs two basic functions:
- Path determination function
- Switching function
- A router knows that the packet should be sent out on a specific port based on the network portion of the address.
Routing Functions
- Path determination function: determines the best direction to send the packet out.
- Switching function: enables a router to accept a packet on one interface and forward it on a second interface.
Prerequisites for Routing
- Design: a plan must exist for assigning addresses, typically broken into fields corresponding to levels in a physical hierarchy.
- Implementation: the design plan must be implemented in switching nodes, which must be able to extract path information from the addresses.
Routing Algorithms and Protocols
- Routing algorithms and protocols form the core of the Internet.
- Network engineers assign costs to network paths, and routing protocols select the least-cost path to the destination.
Types of Routing
- Static Routing: a plan must exist by which addresses are assigned.
- Default Routing: a default route is used when a router does not know where to send a packet.
- Dynamic Routing: routers update their routing tables based on changes in the network.
Routing Updates
- Routing updates are used to inform other routers of changes in the network.
- Figure 4 illustrates dynamic routing, where routers update their routing tables based on changes in the network.
Limitations of Routing
- As networks grow in size, the routing tables also grow proportionately, consuming considerable router memory.
- The processor time is eaten up in scanning these tables and bandwidth is consumed in sending status reports about the updated routing tables.
- Ultimately, the routing has to be done hierarchically, similar to a telephone network.
IP Routing Principles
- IP Routing is a process that sends packets from a host on one network to another host on a different remote network.
- It helps examine the destination IP address of a packet, determine the next-hop address, and forward it.
Switching
- A networking switch is designed to behave like an electrical switch, directing data signals to one of several wires.
- Its primary feature is speed, and it appears like a wire when relaying data signals.
- Layer 2 switches bridge, whereas layer 3 switches route.
- Switches use special silicon chips to forward packets directly from source to destination without passing through RAM buffers.
Routing and Network Layer Addresses
- Routers relay a packet from one data link to another.
- To relay a packet, a router employs two basic functions:
- Path determination function
- Switching function
- A router knows that the packet should be sent out on a specific port based on the network portion of the address.
Routing Functions
- Path determination function: determines the best direction to send the packet out.
- Switching function: enables a router to accept a packet on one interface and forward it on a second interface.
Prerequisites for Routing
- Design: a plan must exist for assigning addresses, typically broken into fields corresponding to levels in a physical hierarchy.
- Implementation: the design plan must be implemented in switching nodes, which must be able to extract path information from the addresses.
Routing Algorithms and Protocols
- Routing algorithms and protocols form the core of the Internet.
- Network engineers assign costs to network paths, and routing protocols select the least-cost path to the destination.
Types of Routing
- Static Routing: a plan must exist by which addresses are assigned.
- Default Routing: a default route is used when a router does not know where to send a packet.
- Dynamic Routing: routers update their routing tables based on changes in the network.
Routing Updates
- Routing updates are used to inform other routers of changes in the network.
- Figure 4 illustrates dynamic routing, where routers update their routing tables based on changes in the network.
Limitations of Routing
- As networks grow in size, the routing tables also grow proportionately, consuming considerable router memory.
- The processor time is eaten up in scanning these tables and bandwidth is consumed in sending status reports about the updated routing tables.
- Ultimately, the routing has to be done hierarchically, similar to a telephone network.
Routing Principles
- Fairness and optimality are competing requirements in routing, with a trade-off between the two.
- Performance criteria may prioritize packet transportation between adjacent stations over distant stations, resulting in higher throughput but unfairness to distant stations.
- Efficiency of a routing technique is determined by the minimum overhead processing required.
Routing Table and ARP Table
- A routing table is used to select the best path for forwarding packets.
- An ARP table is used to map IP addresses to physical addresses.
Routing and Network Layer Addresses
- Routers relay packets between data links using two basic functions: path determination and switching.
- Path determination selects the most appropriate interface for forwarding packets, while switching enables forwarding packets between interfaces.
- Routing assumes that addresses convey partial information about host locations, allowing routers to forward packets without broadcasting or complete listing of destinations.
- Three prerequisites for routing are:
- Design: a plan for assigning addresses, typically broken into fields corresponding to physical hierarchy levels.
- Implementation: the design plan must be implemented in switching nodes, which extract path information from addresses.
- Enforcement: the plan must be enforced in host addressing, with centralized addressing authority.
Routing Protocols
- A routed protocol is a protocol that contains sufficient network-layer addressing information for user traffic to be directed from one network to another.
- Routed protocols define the format and use of packet fields.
- Examples of routed protocols include IP and Novell's IPX.
- A routing protocol provides mechanisms for sharing routing information between routers.
- Routing protocol messages do not carry end-user traffic from network to network.
Types of Routing
- Static routing: routes to destinations are set up manually in the router.
- Dynamic routing: routes are adapted based on changing network conditions.
- Types of dynamic routing include:
- Distance vector routing
- Link state routing
Dynamic Routing Operations
- Two basic router functions are essential for dynamic routing:
- Maintenance of a routing table
- Timely distribution of knowledge to other routers through routing updates
- Dynamic routing relies on a routing protocol to disseminate knowledge.
Convergence
- Convergence refers to the consistency and accuracy of network topology information among routers.
- The network is considered to have converged when all routers contain consistent information.
Representing Distance with Metrics
- Routing algorithms use metrics to determine the best path for forwarding packets.
- Metrics can be based on distance, number of hops, or estimated transit time.
- Distance vector algorithms accumulate network distances to maintain a database of network topology information.
Test your knowledge of IP routing principles and switching concepts, including packet forwarding and data signal direction.
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