Free CCNA | VLANs (Part 3) | Day 18 | CCNA 200-301 Complete Course

Welcome to Jeremy’s IT Lab

In this section, Jeremy introduces his free CCNA course and covers the topic of VLANs.

Introduction

• Jeremy welcomes viewers to his IT Lab and invites them to subscribe and follow along with the series.

• He mentions that this video will cover VLANs for the CCNA certification.

Overview of VLANs

This section provides an overview of VLANs and outlines the topics covered in the video.

Basics of VLANs

• Jeremy mentions that he has already covered the important basics of VLANs but there are still a few more things to know for the CCNA.

• He states that this will be a long video and proceeds to list the topics covered in it.

Topics Covered

• Native VLAN on a router using router-on-a-stick for inter-VLAN routing.

• Wireshark captures to understand dot1q tags.

• Layer 3 switching or multilayer switching for inter-VLAN routing.

• DTP (Dynamic Trunking Protocol) and VTP (VLAN Trunking Protocol) - removed from CCNA exam topics but still important to understand at a basic level.

Using Native VLAN on a Router

This section explains how to use the native VLAN feature on a router when using router-on-a-stick for inter-VLAN routing.

Benefits of Native VLAN

• Frames in the native VLAN are not tagged, making it more efficient as each frame is smaller, allowing more frames per second.

Configuring Native VLAN on a Router

• Two methods:

• Using subinterfaces with ENCAPSULATION DOT1Q vlan-id NATIVE command.

• Configuring IP address directly on physical interface without subinterface. No need for ENCAPSULATION DOT1Q command.

Wireshark Captures and Native VLAN

This section demonstrates the use of Wireshark captures to understand the native VLAN.

Wireshark Capture

• Jeremy sets up a Wireshark capture between R1 and SW2 to monitor traffic.

• He sends an ICMP echo request message from SW2 to R1 for inter-VLAN routing.

Analysis of Capture

• The captured frame shows source and destination IP addresses.

• The Ethernet header encapsulating the IP packet includes a dot1q tag with a TPID field and other fields like PCP (Priority Code Point).

These are the main sections covered in the transcript.

Understanding VLAN Tagging and Native VLAN

In this section, we learn about VLAN tagging and the concept of a native VLAN. We explore how VLAN tags are added to Ethernet headers and how untagged frames are treated in a native VLAN.

VLAN Tagging and Encapsulation

• Ethernet headers include a TYPE field indicating the encapsulated packet type, such as IPv4.

• The dot1q tag is inserted between the SOURCE MAC ADDRESS field and the TYPE field to indicate the VLAN.

• ICMP echo requests can be encapsulated with a new Ethernet header that does not have a dot1q tag.

Native VLAN Function

• The native VLAN is configured as untagged frames on both devices (e.g., R1 and SW2) participating in communication.

• Untagged frames belong to the native VLAN (e.g., VLAN10) without needing explicit dot1q tagging.

• ICMP echo requests in the native VLAN will continue untagged until reaching their destination.

Configuring Native VLAN on a Router

• One method is configuring an IP address directly on the router's physical interface without using subinterfaces or encapsulation commands.

• To configure it, delete the subinterface using NO INTERFACE G0/0.10 command, then configure the appropriate IP address on the interface.

Configuring Native VLAN on a Router

This section explains how to configure the native VLAN on a router by assigning an IP address directly to its physical interface.

Configuring Native VLAN

• Delete any existing subinterface using NO INTERFACE G0/0.10 command.

• Enter interface configuration mode for G0/0 and assign the desired IP address directly to the physical interface.

Inter-VLAN Routing Methods

In this section, we explore different methods of inter-VLAN routing and their advantages.

Inter-VLAN Routing Methods

• Method 1: Using separate connections between the router and switch for each VLAN.

• Method 2: Router on a stick, which uses a single trunk connection to carry traffic from all VLANs between the switch and router.

• In large networks, a multilayer switch is preferred for inter-VLAN routing due to its capabilities.

Introduction to Layer 3 Switches

This section introduces layer 3 switches (multilayer switches) and explains their capabilities in switching, routing, and inter-VLAN communication.

Layer 3 Switches

• A layer 3 switch is capable of both switching and routing.

• It is Layer 3 aware, unlike regular layer 2 switches that only care about MAC addresses.

• Layer 3 switches can have routed ports, physical or virtual interfaces with assigned IP addresses for routing at Layer 3.

• They can also be used for inter-VLAN routing and support configuring routes like static routes.

Inter-VLAN Routing with a Layer 3 Switch

This section demonstrates how inter-VLAN routing is performed using a layer 3 switch instead of a router on a stick.

Inter-VLAN Routing with Layer 3 Switch

• Replace one of the layer 2 switches (SW2) with a layer 3 switch.

• Configure point-to-point Layer 3 links between the new layer 3 switch and other devices.

• Assign IP addresses to the appropriate interfaces on both the new layer 3 switch (SW2's G0/1 interface) and R1's G0/0 interface.

SVIs and Inter-VLAN Routing

This section explains the concept of SVIs (Switch Virtual Interfaces) and how they are used for inter-VLAN routing on a multilayer switch. It also covers the configuration steps involved in setting up SVIs and routing between VLANs.

SVIs and Routing on Multilayer Switches

• SVIs (Switch Virtual Interfaces) are virtual interfaces that can be assigned IP addresses on a multilayer switch.

• PCs can be configured to use the SVI as their gateway address instead of a router when performing inter-VLAN routing.

• Traffic between different subnets/VLANs is sent to the switch, which then routes the traffic using its own routing table.

• The destination MAC address is checked in the switch's MAC address table, and if not found, the frame is flooded to all interfaces in the corresponding VLAN.

• To reach destinations outside of the LAN, SW2 (the default gateway for hosts) needs additional configurations.

Configuring Point-to-Point Link and SVIs on SW2

• A point-to-point link between SW2 and R1 is established by assigning IP addresses to their respective physical interfaces.

• The G0/1 interface of SW2 is configured with an IP address of 192.168.1.193/30, while R1's G0/0 interface has an IP address of 192.168.1.194/30.

• Layer 3 routing on SW2 is enabled using the command IP ROUTING.

• The G0/1 interface on SW2 is changed from a Layer 2 switchport to a Layer 3 routed port using NO SWITCHPORT command.

• A default route pointing towards R1 (next hop: 192.168.1.194) is configured on SW2 using IP ROUTE 0.0.0.0 0.0.0.0.

Configuring SVIs on SW2

• SVI configuration on SW2 is straightforward.

• Each VLAN (e.g., VLAN10, VLAN20, VLAN30) is associated with an SVI using the command INTERFACE VLANX.

• An IP address is assigned to each SVI, and the NO SHUTDOWN command is used to enable them.

Troubleshooting and Conclusion

This section covers troubleshooting tips and demonstrates a potential problem that may arise during SVI configuration.

Troubleshooting and Potential Issues

• When configuring SVIs, it's important to remember to use the NO SHUTDOWN command to enable them since they are shutdown by default.

• If subinterfaces were previously configured for router-on-a-stick setup, they need to be deleted before configuring new SVIs.

• Deleting subinterfaces does not remove them completely; they remain in a "deleted" status until the router is reloaded.

• The status of interfaces can be checked using the SHOW IP INTERFACE BRIEF command.

• For point-to-point links between switches and routers, physical interfaces can be configured as Layer 3 routed ports instead of switchports.

Conclusion

• Switch Virtual Interfaces (SVIs) are used for inter-VLAN routing on multilayer switches.

• PCs can be configured to use SVIs as their gateway addresses instead of routers.

• Point-to-point links between switches and routers can be established by assigning IP addresses to their respective physical interfaces.

• Layer 3 routing must be enabled on switches using the IP ROUTING command for inter-VLAN communication.

• Troubleshooting steps include deleting previous configurations, checking interface statuses, and ensuring proper enabling of SVIs.

New Section

This section discusses the requirements for the SVI (Switched Virtual Interface) to become UP/UP on a switch.

Requirements for SVI to Become UP/UP

• The VLAN must exist on the switch. If the VLAN does not exist, the SVI will not become UP/UP.

• The switch must have at least one access port or trunk port in an up/up state in the VLAN.

• The VLAN itself must not be shutdown. Disabling the VLAN with the SHUTDOWN command will prevent the SVI from becoming UP/UP.

• If the SVI itself is shutdown, it won't be up/up. Use the NO SHUTDOWN command after creating an SVI to enable it.

New Section

This section covers additional rules for SVIs and shows how connected and local routes are added to the route table for each SVI.

Additional Rules for SVIs

• The VLAN must not be shutdown (not applicable to the SVI itself).

• Use SHOW IP ROUTE command to view connected and local routes added to the route table for each SVI.

New Section

This section explains how inter-VLAN routing works within a LAN and mentions that no routes were configured on R1 in this lab.

Inter-VLAN Routing

• Traffic from a PC within a LAN destined for a destination outside of the LAN is sent to SW2, which forwards it to R1.

• SW2 performs inter-VLAN routing without involving R1 when a PC wants to reach a destination within a different subnet and VLAN.

• No routes were configured on R1 in this lab as it focuses solely on inter-VLAN routing.

New Section

This section summarizes the topics covered in the video, including configuring the native VLAN on a router and using a Layer 3 switch for inter-VLAN routing.

Summary of Covered Topics

• Configuring the native VLAN on a router using two methods: ENCAPSULATION DOT1Q NATIVE command on subinterface or configuring IP address on physical interface.

• Analyzing Wireshark captures of dot1q-tagged and untagged frames in the native VLAN.

• Introducing Layer 3 switches (multilayer switches) and their ability to perform inter-VLAN routing using SVIs.

• DTP (Dynamic Trunking Protocol) and VTP (VLAN Trunking Protocol) will be discussed in the next lecture video.

New Section

This section introduces a quiz and mentions Boson's ExSim practice exams for CCNA.

Quiz Introduction

• A quiz with questions to review what was learned in the video is presented.

• One question from Boson's ExSim practice exams for CCNA is featured.

• Boson ExSim is recommended as a helpful resource for exam preparation.

New Section

This section provides answers to question 1 of the quiz, which focuses on configuring the native VLAN on a router in a ROAS configuration.

Quiz Question 1 Answer

• Two valid options to configure the native VLAN on a router in a ROAS configuration are:

• Option B: Using ENCAPSULATION DOT1Q NATIVE command on subinterface.

• Option C: Configuring IP address directly on physical interface without ENCAPSULATION DOT1Q command.

New Section

This section provides answers to question 2 of the quiz, which addresses an SVI remaining down/down despite being configured.

Quiz Question 2 Answer

• Two possible reasons for an SVI remaining down/down are:

• Option A: The VLAN associated with the SVI does not exist on the switch.

• Option D: No interfaces in the VLAN associated with the SVI are in an up/up state.

New Section

This section provides answers to question 3 of the quiz, which asks about configuring a switch interface as a routed port.

Quiz Question 3 Answer

• The command used to configure a switch interface as a routed port is:

• Option A: no switchport.

New Section

This section discusses a practice question related to VLAN traffic on a Catalyst 2950 switch.

Understanding VLAN Traffic on FastEthernet0/7

• VLAN 1 traffic will be untagged.

• VLAN 44 traffic will be untagged.

• All VLAN traffic will be tagged.

• All VLAN traffic will be untagged.

Correct Answer and Explanation

The correct answer is B: VLAN 44 traffic will be untagged because the SWITCHPORT TRUNK NATIVE VLAN 44 command was issued.

• Traffic from VLAN 44 will be untagged when sent over port FastEthernet0/7.

• The native VLAN has been configured as VLAN 44 using the SWITCHPORT TRUNK NATIVE VLAN (vlan-id) command.

• By default, the native VLAN is VLAN 1, but it was changed to VLAN 44 in this scenario.

Additional Information and Resources

• The SHOW INTERFACES TRUNK command can display the list of ports configured for trunking, the native VLAN for each port, and the currently allowed VLANs for each trunk port.

• Further reading on Ethernet virtual LANs (VLANs) can be found in Cisco's official cert guide, Volume 1, Chapter 8.

• Links to additional Cisco documentation and resources are provided in the video description.

New Section

This section provides information about supplementary materials and resources related to the practice question discussed earlier.

Supplementary Materials and Resources

• Boson ExSim practice exams are highly recommended for further preparation.

• Link to download Boson ExSim is provided in the video description.

• Review flashcard deck for use with the software 'Anki' is available for download.

• Link to download the flashcard deck is provided in the video description.

• Packet tracer practice lab for practicing configurations from the video will be available in a separate video.

Shoutout to Channel Members

A shoutout is given to JCNP-level channel members, expressing gratitude for their support.

Conclusion and Call to Action

• Viewers are encouraged to subscribe to the channel, like the video, leave comments, and share it with others studying for CCNA.

• Tips can be given via Basic Attention Token (BAT) or through other links provided in the video description.