IT2050 Computer Networks Routing Protocols
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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?

    <p>Exterior Gateway Protocol (EGP)</p> Signup and view all the answers

    Which exit interface corresponds to the destination network 172.17.3.0?

    <p>S1</p> Signup and view all the answers

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

    <p>The packet should move from router to router.</p> Signup and view all the answers

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

    <p>Host Specific Routing</p> Signup and view all the answers

    What is a significant disadvantage of Host Specific Routing?

    <p>Updating the table is complex due to numerous records.</p> Signup and view all the answers

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

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

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

    <p>Connected update</p> Signup and view all the answers

    What is one advantage of adaptive routing?

    <p>It minimizes network traffic.</p> Signup and view all the answers

    What is NOT a basic method to update routing tables?

    <p>Informed</p> Signup and view all the answers

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

    <p>Flooding</p> Signup and view all the answers

    What is expiration time in the context of routing protocols?

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

    What is the primary reason for slow convergence in RIP?

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

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

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

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

    <p>The creation of loops that may destabilize the network.</p> Signup and view all the answers

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

    <p>Triggered updates.</p> Signup and view all the answers

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

    <p>Connected networks</p> Signup and view all the answers

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

    <p>ip route</p> Signup and view all the answers

    What is a potential disadvantage of static routing?

    <p>Configuration is time-consuming</p> Signup and view all the answers

    What type of networks primarily use default routing?

    <p>Stub networks</p> Signup and view all the answers

    Which of the following static routes is configured correctly?

    <p>ip route 172.16.1.0 255.255.255.0 172.16.2.2</p> 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?

    <p>This is a static route to the subnet through a gateway</p> Signup and view all the answers

    What must an administrator have to implement static routing properly?

    <p>Complete knowledge of the entire network</p> Signup and view all the answers

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

    <p>A default static route</p> Signup and view all the answers

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

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

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

    <p>To ignore updates regarding a network for a specified period after a failure is detected.</p> 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?

    <p>IGRP</p> Signup and view all the answers

    What is unique about the EIGRP protocol compared to IGRP?

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

    Poison Reverse is applied in which scenario?

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

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

    <p>It was initially available only on Cisco devices.</p> Signup and view all the answers

    What issue is Split Horizon designed to address in routing?

    <p>The risk of routing loops.</p> Signup and view all the answers

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

    <p>100</p> 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.

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    Related Documents

    CN IT2050 Lecture 4 Routing Protocols PDF

    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.

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