Which two statements are true about link-state routing protocols? (Choose two.)

Link-state routing protocols, such as OSPF, are designed for efficiency and accuracy. They achieve this by having each router build a complete map of the network topology. Updates, known as Link-State Advertisements (LSAs), are not sent periodically but are triggered by an event, such as a link failure or a change in link cost. This makes the protocol efficient in stable networks. To ensure every router maintains an identical and accurate topology database, these updates are flooded throughout the network using a reliable transport mechanism that includes acknowledgments, ensuring all neighbors receive the information correctly.

C. Link-state protocols use a metric called 'cost,' typically derived from bandwidth, not hop-count, which is characteristic of distance-vector protocols like RIP.

D. Dijkstra's algorithm, used by link-state protocols, is more processor-intensive than distance-vector algorithms because it calculates a complete topology map.

1. Kurose

J. F.

& Ross

K. W. (2017). Computer Networking: A Top-Down Approach (7th ed.). Pearson. In Chapter 5.2

"The Link-State (LS) Routing Algorithm

" the text states

"LS is an algorithm with global state information... The algorithm is often referred to as Dijkstra's algorithm... When a link's cost changes

the link-state broadcast algorithm is initiated." This confirms that updates are event-triggered (A) and that Dijkstra's is the link-state algorithm (relevant to D).

2. Moy

J. (1998). RFC 2328: OSPF Version 2. IETF. Section 13

"The Flooding Procedure

" describes the reliable mechanism for disseminating link-state advertisements using Link State Update and Link State Acknowledgment packets

which supports the claim of a reliable update mechanism (B).

3. Stanford University. (2013). CS144: Introduction to Computer Networking

Lecture 13 - Routing. [Lecture Slides]. Slide 23 compares Distance Vector and Link State

noting that Link State has a "high computation cost" (Dijkstra's algorithm) and that Distance Vector (RIP) uses "hop count" as a metric (relevant to C). This confirms the reasoning for D and C being incorrect. Available at: https://web.stanford.edu/class/cs144/lectures/13-routing.pdf