What is the primary purpose of an IRB Layer 3 interface?

Question

Options

• Ato provide load balancing
• Bto provide a default VLAN ID
• Cto provide inter-VLAN routing
• Dto provide port security

• A
  3% (1)
• B
  6% (2)
• C
  89% (31)
• D
  3% (1)

Explanation

The primary purpose of an IRB (Integrated Routing and Bridging) interface is to enable inter- VLAN routing in a Layer 3 environment. An IRB interface in Junos combines the functionality of both Layer 2 bridging (switching) and Layer 3 routing, allowing devices in different VLANs to communicate with each other. VLANs and Layer 2 Switching: Devices within the same VLAN can communicate directly through Layer 2 switching. However, communication between devices in different VLANs requires Layer 3 routing. IRB Interface for Inter-VLAN Routing: The IRB interface provides a Layer 3 gateway for each VLAN, enabling routing between VLANs. Without an IRB interface, devices in different VLANs would not be able to communicate. In Juniper devices, the IRB interface is configured by assigning Layer 3 IP addresses to it. These IP addresses serve as the default gateway for devices in different VLANs. Example configuration: set interfaces irb unit 0 family inet address 192.168.1.1/24 set vlans vlan-10 l3-interface irb.0 This allows VLAN 10 to use the IRB interface for routing.

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