Integrated Routing and Bridging (IRB)

You have just learned how to create a Layer 2 bridge group on a threat defense in transport mode. Also, the preceding chapter described how to configure Layer 3 interfaces in routed mode. On a traditional firewall, when you enable a firewall mode, all the interfaces on that firewall solely support that particular mode. Because each routed interface or Bridge Virtual Interface (BVI) represents a separate subnet, a router is essential to route traffic between the different subnets. However, in your deployment use case, if you need to configure some interfaces in routed mode, while the other interfaces will run in bridge groups, you can configure your threat defense to do so. A single threat defense can route traffic between any regular routed interfaces and Bridge Virtual Interfaces natively and simultaneously. This functionality is known as integrated routing and bridging (IRB). IRB enables you to deploy a threat defense in diverse design scenarios, as it integrates the capabilities of separate Layer 2 and Layer 3 devices into a single device.

Summary

This chapter discusses the transparent firewall mode and how to configure the physical and virtual interfaces. It discusses integrated routing and bridging (IRB). Furthermore, it describes various command-line tools that enable you to investigate any potential configuration issues.

Exam Preparation Tasks

As mentioned in the section “How to Use This Book” in the Introduction, you have a couple of choices for exam preparation: the exercises here, Chapter 22, “Final Preparation,” and the exam simulation questions in the Pearson Test Prep practice test software.

Review All Key Topics

Review the most important topics in this chapter, noted with the Key Topic icon in the outer margin of the page. Table 5-3 lists a reference of these key topics and the page numbers on which each is found.

Table 5-3 Key Topics for Chapter 5

Key Topic Element	Description	Page
Paragraph	Transparent mode	92
Bullet list	Bridge Virtual Interface (BVI)	94
Bullet list	Special handling of traffic	94
Paragraph	Integrated routing and bridging (IRB)	118