Question

Difficulty: MediumNetwork Components Roles and Functions

An enterprise network engineer is reviewing the functional boundaries of network components deployed at a branch office. The topology includes Layer 2 access switches, a Layer 3 distribution switch acting as the Inter-VLAN routing gateway, and a perimeter router. Which two functions are performed by Layer 3 switches or routers, but are NOT supported on standard Layer 2 switches? (Choose two.)

  1. Forwarding traffic between different IPv4 subnets using IP header destination addressesAnswer
  2. Containing broadcast traffic to specific VLANs by acting as default gateways for routed subnetsAnswer
  3. C
    Dividing the physical network into separate collision domains on a per-port basis
  4. D
    Providing bare-metal Type 1 hypervisor hosting capabilities to run virtual endpoints directly inside hardware switch ASICs

Answer

The functions performed exclusively by Layer 3 switches or routers are forwarding traffic between different IPv4 subnets based on destination IP addresses and containing broadcast domains by acting as default gateways.
Layer 3 switches and routers operate at Layer 3 of the OSI model, allowing them to inspect destination IP addresses to route packets between distinct subnets and restrict broadcast traffic from crossing subnets. Standard Layer 2 switches only forward frames within a single VLAN based on Layer 2 MAC addresses.

Step-by-Step Solution

1
Analyze the operational capabilities of standard Layer 2 switches
Layer 2 switches make forwarding decisions based on Layer 2 MAC addresses within a single broadcast domain/subnet and separate collision domains per port.
Layer 2 switches lack routing logic and routing tables needed to forward packets across different subnets.
2
Analyze the operational capabilities of Layer 3 switches and routers
Layer 3 switches and routers inspect Layer 3 IP headers to route packets between subnets and define broadcast domain boundaries.
Broadcast frames are not forwarded past Layer 3 boundaries (routers/L3 interfaces), isolating broadcast domains.
3
Compare capabilities and identify unique Layer 3 functions
Inter-subnet routing based on IP destination addresses and broadcast domain isolation are Layer 3 routing functions.
Collision domain isolation is accomplished by both Layer 2 and Layer 3 switches on every port.

Key Concept

Distinguishing Layer 2 switching capabilities (MAC addressing, collision domain segmentation) from Layer 3 routing capabilities (IP addressing, inter-subnet forwarding, broadcast domain segmentation).
Estimated Time:1m 30s
Rate this question