How many collision domains are in Fig 1? Explain your answer
How many broadcast domains are in Fig 1? Explain your answer
The Correct Answer and Explanation is:
Answer:
- Collision Domains: 9
- Broadcast Domains: 3
Explanation
In Figure 1, the network topology includes 3 routers (Router0, Router1, Router2) and 4 switches (Switch0, Switch1, Switch2, Switch3). To calculate collision and broadcast domains, we must understand the behavior of each device.
Collision Domains:
A collision domain is a network segment where data packets can collide with each other when sent on a shared medium, typically found in hubs or half-duplex Ethernet. However, modern switches and routers break collision domains.
- Each port on a switch represents a separate collision domain because switches operate at Layer 2 and forward traffic based on MAC addresses, isolating collisions.
- Each router interface also represents a separate collision domain because routers operate at Layer 3 and do not forward Ethernet frames.
In the diagram:
- Each switch has one connection shown (so 4 ports → 4 collision domains).
- Router1 connects to 3 switches and 2 routers (5 interfaces = 5 collision domains).
Collision domain breakdown:
- Router0 to Switch0: 1
- Router1 to Switch1, Switch2, and two routers: 4
- Router2 to Switch3: 1
- Switch0, Switch1, Switch2, Switch3 ports: 4
Total collision domains = 1 (Router0-Switch0) + 4 (Router1 connections) + 1 (Router2-Switch3) + 3 remaining switch ports = 9
Broadcast Domains:
A broadcast domain is a network segment where a broadcast frame is forwarded. Routers break broadcast domains, while switches extend them.
In the diagram:
- Each router interface marks a broadcast boundary.
- Routers connect 3 separate networks: one for each LAN segment.
Broadcast domain breakdown:
- Router0–Switch0 segment: 1
- Router1–Switch1 & Switch2 segment: 1
- Router2–Switch3 segment: 1
Total broadcast domains = 3
Thus, Figure 1 has 9 collision domains and 3 broadcast domains.
