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Difficulty: MediumRouting Concepts and Dynamic Routing Protocols

A network architect is evaluating dynamic routing protocol behaviors for an enterprise network expansion. Which of the following statements accurately contrast the operational characteristics and algorithms of link-state routing protocols with distance-vector routing protocols? (Select TWO.)

  1. Link-state protocols maintain a complete topology database of the network before calculating paths, whereas distance-vector protocols rely on routing updates received from immediate neighbors.Answer
  2. B
    Distance-vector protocols calculate path metrics based strictly on interface bandwidth and latency, whereas link-state protocols evaluate path quality based solely on hop count.
  3. Link-state protocols calculate optimal paths using Dijkstra's Shortest Path First (SPF) algorithm, whereas distance-vector protocols compute routes using the Bellman-Ford algorithm.Answer
  4. D
    Distance-vector routing updates operate at Layer 3 of the OSI model, whereas link-state protocols function exclusively at Layer 2 using unrouted Ethernet frames.

Answer

Link-state protocols maintain a complete topology database of the network before calculating paths, whereas distance-vector protocols rely on routing updates received from immediate neighbors; and link-state protocols calculate optimal paths using Dijkstra's Shortest Path First (SPF) algorithm, whereas distance-vector protocols compute routes using the Bellman-Ford algorithm.
The correct selections describe fundamental operational differences between dynamic routing protocol classes: (1) Link-state protocols assemble a complete topological map (LSDB) before determining optimal paths, while distance-vector protocols rely on periodic vector updates from adjacent neighbors ('routing by rumor'); and (2) Link-state protocols apply Dijkstra's Shortest Path First (SPF) algorithm to their topology database, while distance-vector protocols use the Bellman-Ford algorithm.

Step-by-Step Solution

1
Analyze network topology visibility across routing protocol families
Link-state protocols (such as OSPF) build a complete link-state database (LSDB) representing the entire network topology before running path calculation. Distance-vector protocols (such as RIP) only receive destination subnets and distance values from adjacent neighbors.
This core distinction defines how topology information is gathered and maintained.
2
Evaluate path calculation algorithms
Link-state protocols process their LSDB using Dijkstra's Shortest Path First (SPF) algorithm to construct a shortest-path tree. Distance-vector protocols calculate route metric updates using the Bellman-Ford routing algorithm.
Algorithmic foundation differentiates link-state database processing from distance-vector metric accumulation.
3
Verify metric definitions and protocol layering
Link-state protocols evaluate cost based on bandwidth, while standard distance-vector protocols use hop count. Both protocol families serve Layer 3 network routing operations.
Options reversing metrics or categorizing link-state protocols as Layer 2 mechanisms are incorrect.

Key Concept

Operational Differences Between Link-State and Distance-Vector Routing Protocols
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Topics

Routing Concepts and Dynamic Routing Protocols

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