Explain how network traffic is routed between VLANs in a converged network. Configure inter-VLAN routing on a router to enable communications between end-user devices on separate VLANs Troubleshoot common inter-VLAN connectivity issues.

• Functionally, the router-on-a-stick model for inter-VLAN routing is the same as using the traditional routing model, but instead of using the physical interfaces to perform the rout[r]

CCNA – Semester1

Chapter 6 Inter – VLAN Routing

-CCNA Exploration version 4.0

Objectives

• Explain how network traffic is routed between

VLANs in a converged network.

• Configure inter-VLAN routing on a router to

enable communications between end-user devices on separate VLANs

• Troubleshoot common inter-VLAN

connectivity issues.

Introduction

Introduction

Inter-VLAN Routing permits computers on separate VLANs can communicate with each other

Traditional Inter-VLAN Routing

• In a traditional network that uses multiple VLANs to

segment the network traffic into logical broadcast domains, routing is performed by connecting different physical router interfaces to different physical switch ports

"Router-on-a-stick" Inter-VLAN Routing

• "Router-on-a-stick" is a type of router configuration in which

a single physical interface routes traffic between multiple

VLANs on a network

Switched-based Inter-VLAN Routing

• Some switches can perform Layer 3 functions, replacing the need for dedicated routers to perform basic routing on a

network Multilayer switches are capable of performing VLAN routing

Interface and Subinterface

Interface Configuration

Subinterface

• To overcome the hardware limitations of inter-VLAN routing based on router physical interfaces, virtual subinterfaces and trunk links are used

• Each subinterface is configured with its own IP address,

subnet mask, and unique VLAN assignment, allowing a

single physical interface to simultaneously be part of multiple logical networks

• Functionally, the router-on-a-stick model for inter-VLAN

routing is the same as using the traditional routing model,

but instead of using the physical interfaces to perform the

routing, subinterfaces of a single interface are used

Subinterface (cont)

Subinterface Configuration

Comparison

Features Physical Interface Subinterface

Port Limits One physical interface

per VLAN

One physical interface for many VLANs

Performance No bandwidth contention Bandwidth contention

Access Ports and

Trunk Ports

Connected to access mode switch port

Connected to trunk mode switch port

Complexity More complex

connection configuration

Less complex connection configuration

Configure Inter-VLAN Routing

Configure Traditional Inter-VLAN Routing

Switch Configuration

Configure Traditional Inter-VLAN Routing

Router Configuration

Configure Traditional Inter-VLAN Routing

Configure Router-on-a-Stick Inter-VLAN Routing

Switch Configuration

Configure Router-on-a-Stick Inter-VLAN Routing

Router Configuration

Configure Router-on-a-Stick Inter-VLAN Routing

Some ISSUES with

Inter-VLAN Routing

Switch Configuration Issues

• Switch ports are not configured on the correct VLAN

• No redundant connection or path between the devices

Router Configuration Issues

• Connect the physical router interface to the wrong switch

port, placing it on the incorrect VLAN and preventing it from reaching the other VLANs

Router Configuration Issues

Router R1 has been configured to use the wrong VLAN on

subinterface F0/0.10, preventing devices configured on

VLAN10 from communicating with subinterface F0/0.10

IP Addressing Issues

Router R1 has been configured with an incorrect IP address

on interface F0/0 This prevents PC1 from being able to

communicate with router R1 on VLAN10

IP Addressing Issues (cont)

PC1 has been configured with an incorrect IP address for the subnet associated with VLAN10 This prevents PC1 from

being able to communicate with router R1 on VLAN10

IP Addressing Issues (cont)

PC1 has been configured with the incorrect subnet mask

Summary