IT2050 Computer Networks Routing Protocols

Questions and Answers

What is the primary function of routing protocols in computer networks?

Storing data packets for future transmission

Encrypting data before sending it over the network

Managing user access and permissions

Dynamically advertising and learning routes (correct)

Which of the following protocols is categorized as an Interior Gateway Protocol (IGP)?

Enhanced Interior Gateway Routing Protocol (EIGRP) (correct)

Routing Information Protocol (RIP) (correct)

Open Shortest Path First (OSPF) (correct)

Border Gateway Protocol (BGP)

What is an Autonomous System (AS) in networking?

The public internet infrastructure

A single router managing multiple networks

A collection of routers under common administration (correct)

A type of network(configuration) for external communications

Which protocol would be most appropriate for routing between different autonomous systems?

Exterior Gateway Protocol (EGP) Signup and view all the answers

Which exit interface corresponds to the destination network 172.17.3.0?

S1 Signup and view all the answers

What is required for a packet to travel from source to destination in a network?

The packet should move from router to router. Signup and view all the answers

Which routing strategy requires a router to maintain a single record for each host?

Host Specific Routing Signup and view all the answers

What is a significant disadvantage of Host Specific Routing?

Updating the table is complex due to numerous records. Signup and view all the answers

What is the main advantage of Network Specific Routing compared to Host Specific Routing?

It allows easier updates as only network records are maintained. Signup and view all the answers

Which routing table update method allows routers to automatically identify connected networks?

Connected update Signup and view all the answers

What is one advantage of adaptive routing?

It minimizes network traffic. Signup and view all the answers

What is NOT a basic method to update routing tables?

Informed Signup and view all the answers

Which of the following routing strategies is characterized by sending packets to all possible routes?

Flooding Signup and view all the answers

What is expiration time in the context of routing protocols?

The duration after which updates from a neighboring router are removed if not received. Signup and view all the answers

What is the primary reason for slow convergence in RIP?

All routers must wait for a complete update cycle. Signup and view all the answers

In the context of RIP, what does route poisoning achieve?

It marks a down network as unreachable by setting its hop count to 16. Signup and view all the answers

What problem arises from routers continuously sending updates back to each other?

The creation of loops that may destabilize the network. Signup and view all the answers

What mechanism allows immediate notification of necessary routing updates in RIP?

Triggered updates. Signup and view all the answers

What does the code 'C' represent in the routing table?

Connected networks Signup and view all the answers

Which command is used to enter a static route in the router's configuration?

ip route Signup and view all the answers

What is a potential disadvantage of static routing?

Configuration is time-consuming Signup and view all the answers

What type of networks primarily use default routing?

Stub networks Signup and view all the answers

Which of the following static routes is configured correctly?

ip route 172.16.1.0 255.255.255.0 172.16.2.2 Signup and view all the answers

What is indicated by the entry 'S 192.168.1.0/24 [1/0] via 172.16.2.2' in the routing table?

This is a static route to the subnet through a gateway Signup and view all the answers

What must an administrator have to implement static routing properly?

Complete knowledge of the entire network Signup and view all the answers

What does the command 'ip route 0.0.0.0 0.0.0.0' configure?

A default static route Signup and view all the answers

What is the primary function of Split Horizon in routing protocols?

To avoid sending the same information back to the router from which it originated. Signup and view all the answers

What is the purpose of a hold down timer in routing protocols?

To ignore updates regarding a network for a specified period after a failure is detected. Signup and view all the answers

Which routing protocol is characterized as a Cisco proprietary distance-vector protocol with a maximum hop count of 255?

IGRP Signup and view all the answers

What is unique about the EIGRP protocol compared to IGRP?

EIGRP was made an open standard allowing interoperability with non-Cisco devices. Signup and view all the answers

Poison Reverse is applied in which scenario?

To prevent loops by indicating that a certain route is down. Signup and view all the answers

What characteristic differentiates EIGRP from other protocols regarding its initial release?

It was initially available only on Cisco devices. Signup and view all the answers

What issue is Split Horizon designed to address in routing?

The risk of routing loops. Signup and view all the answers

What is the administrative distance (AD) associated with IGRP?

100 Signup and view all the answers

Study Notes

Packet Transmission

Packets travel through a network from router to router, requiring routers to maintain routing tables.
Routers analyze IP packets to select the correct path based on the routing table.
Indirect delivery of packets is facilitated by various routing strategies.

Routing Strategies

Four main routing strategies exist: Fixed Routing, Flooding, Random Routing, Adaptive Routing.
Adaptive Routing allows routers to adjust routing tables automatically based on changing network conditions.
Advantages of adaptive routing include minimized traffic, low latency, and optimal route selection; however, it requires memory to maintain routing tables.

Routing Methods in Adaptive Routing

Next Hop Routing: Can be host-specific or network-specific.
Default Routing: Used to set a route for unrecognized destination IP addresses, typically in stub networks.

Host Specific Routing

Each entry in the routing table corresponds to an individual host, detailing Host IP and Interface information.
Disadvantages include a large number of records and complex updates if host IPs change.

Network Specific Routing

Maintains one entry per network, simplifying updates and limiting the number of records.
Provides easier management compared to host-specific entries.

Routing Table Update Methods

Connected: Automatically updates the routing table when routers are connected to a network.
Static: Routing table entries are manually entered by the administrator; while easier to understand, it can be time-consuming and error-prone.
Dynamic: Automatically adapts to changes in the network.

Default Routing

The last entry in a routing table directs traffic if no match is found for a destination IP.
Commonly utilized in stub networks, which have a single exit point.

Routing Protocols

Autonomous System (AS): A collection of routers under a unified administration.
IGP (Interior Gateway Protocols): Used for routing within an AS.
EGP (Exterior Gateway Protocols): Used for routing between multiple ASes.

Expiration Timer

Updates from neighboring routers that are not received within a set time (typically 180 seconds) lead to the removal of that information, indicating a potential issue.

Challenges with RIP (Routing Information Protocol)

Slow Convergence: Routing tables are updated every 30 seconds, causing delays. Triggered updates help mitigate this by sending immediate changes.
Counting to Infinity: When a network fails, affected routers mark it as unreachable (infinity hops) to prevent misinformation cycles.
Instability: Updates can create incorrect tables over time. Solutions include Split Horizon to prevent sending back information received from a router.

Solutions to Common Routing Issues

Hold Down Timer: Temporarily ignores updates about a downed network, preventing erroneous routing decisions.
Poison Reverse: Ensures that routing table info related to downed networks does not get confused with other updates.

IGRP and EIGRP

IGRP (Interior Gateway Routing Protocol): Cisco's proprietary distance-vector protocol, limited to a maximum hop count of 255.
EIGRP (Enhanced IGRP): Updates the original IGRP protocol, released in 1992; made an open standard by Cisco in 2013 for interoperability with various routers.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers essential concepts in routing protocols within the IT2050 Computer Networks course. It focuses on the functioning of routing tables and the decision-making process for packet delivery from source to destination. Test your understanding of how routers choose paths and maintain efficient communication across the network.