Implementing Trunking with 802.1q Ethernet Trunks

Questions and Answers

What does the command 'switchport mode access' do?

Configures the port as an access port for one VLAN (correct)

Disables DHCP services on the port

Configures the port as a trunk port

Enables negotiation of a trunk on the port

Why did the PC not receive an IP address initially?

The PC was not connected to the correct VLAN

DHCP services were not enabled on MLS1

The trunk between MLS1 and MLS2 was not configured

The VLAN interfaces on MLS1 were down (correct)

What is the purpose of recreating the VLAN interfaces on MLS1?

To bring up the logical layer 3 interfaces (correct)

To enable trunking between MLS1 and MLS2

To enable DHCP services on MLS1

To change the VLAN IDs

What is the function of the 'show interface status' command?

To display the status of the physical interfaces Signup and view all the answers

What is the purpose of using the 'no interface vlan 10' and 'no interface vlan 20' commands?

To delete the VLAN interfaces and recreate them Signup and view all the answers

What is the purpose of the 'show ip interface brief' command?

To display the IP address configuration of the interfaces Signup and view all the answers

Why did the capture show multiple discover messages with incorrect tags?

Because the VLAN interfaces on MLS1 were down Signup and view all the answers

What is the purpose of using the display filter 'DHCP' in the capture?

To display only the DHCP traffic in the capture Signup and view all the answers

What is the function of the 'show vlan brief' command?

To display the VLAN membership of the interfaces Signup and view all the answers

What is the purpose of stopping and starting the capture on the PC?

To verify that the VLAN tagging is working correctly Signup and view all the answers

Why was there no tag added to the DHCP discover message coming from PC2?

The trunk port on MLS2 was not configured to be in a specific VLAN, so the traffic was treated as native VLAN traffic and not tagged. Signup and view all the answers

What is the purpose of the 802.1q tag in the demonstration?

To associate the frame with VLAN 10 Signup and view all the answers

Why did the DHCP discover messages from PC2 not receive a response?

The DHCP server on MLS1 was not able to see the DHCP discover messages due to the missing VLAN tag. Signup and view all the answers

What type of message was sent by the device to initiate the discovery process?

Layer 2 broadcast Signup and view all the answers

Which of the following best describes the role of the trunk port on MLS2 in this scenario?

To allow traffic to be forwarded between MLS2 and MLS1 with tagging for identification. Signup and view all the answers

What happens to the 802.1q tag when the frame is received by MLS2?

It is stripped off and not used anymore Signup and view all the answers

Why was only one interface used between MLS1 and MLS2?

Due to layer 2 detection by spanning tree Signup and view all the answers

What is the function of the layer 3 logical interface for VLAN 10 on MLS1?

To provide a gateway for devices on VLAN 10 to access other networks. Signup and view all the answers

What is the importance of associating end devices with the correct VLANs?

To ensure correct forwarding of traffic Signup and view all the answers

What is the significance of the 'native VLAN' on a trunk port?

The native VLAN is the VLAN that traffic is assigned to if it does not have a VLAN tag. Signup and view all the answers

What is the role of MLS1 in the demonstration?

It acts as a layer 2/3 multilayer switch Signup and view all the answers

What command was used to verify the VLAN assignments on MLS2?

show vlan brief Signup and view all the answers

What is the purpose of the switched virtual interface on MLS1?

To forward traffic to other devices in the same VLAN Signup and view all the answers

What command was used to configure Gig 0/0 on MLS2 as an access port associated with VLAN 10?

interface gig 0/0; switchport mode access; switchport access vlan 10 Signup and view all the answers

What is the outcome of the troubleshooting process in the demonstration?

The VLAN associations were incorrect Signup and view all the answers

What is the purpose of capturing traffic on the trunk port between MLS2 and MLS1?

To verify that VLAN tags are being added to traffic sent from MLS2 to MLS1. Signup and view all the answers

What is the meaning of the term 'DHCP discover' as mentioned in this scenario?

A request from a device on the network to find a DHCP server. Signup and view all the answers

What is the significance of the 'layer 2 and 1/2' term used in the demonstration?

It refers to the VLAN tagging process Signup and view all the answers

What is the relevance of implementing trunking between MLS1 and MLS2?

To extend VLANs across multiple switches Signup and view all the answers

What is the primary benefit of using VLANs in a network?

All of the above. Signup and view all the answers

What command is used to display the interfaces operating as an 802.1q trunk on a Cisco switch?

show interface trunk Signup and view all the answers

What encapsulation method is specified for the switchports in the configuration?

dot1q Signup and view all the answers

Which interfaces are configured simultaneously on MLS1 for trunking?

Gig 0/1 and Gig 1/1 Signup and view all the answers

What is the main advantage of using the interface range command during configuration?

It speeds up the configuration process. Signup and view all the answers

What command follows the entry into configuration mode to set the trunk encapsulation to dot1q?

switchport trunk encapsulation dot1q Signup and view all the answers

What is the purpose of using the command 'configure space terminal'?

To access configuration mode. Signup and view all the answers

Which encapsulation method is considered outdated and not used anymore?

ISL Signup and view all the answers

What will the 'show interface trunk' command display if no trunks are configured?

No interfaces are operating as trunks Signup and view all the answers

What command is used to set a port to operate as a trunk on a Cisco multilayer switch?

switchport mode trunk Signup and view all the answers

Which VLANs were created on MLS1 as mentioned?

VLAN 10 and 20 Signup and view all the answers

What does the command 'no shutdown' accomplish on a Cisco device?

It activates the specified interface. Signup and view all the answers

What encapsulation method is used for trunking between the devices?

802.1q Signup and view all the answers

What should the output indicate when running 'show interface trunk' on MLS1?

Gig 0/1 and Gig 1/1 are trunks Signup and view all the answers

What function does a trunk port serve in the VLAN context?

It carries traffic for multiple VLANs between switches. Signup and view all the answers

If VLAN 20 exists already, what happens when the command to create it is sent again?

It will remain unchanged and no error occurs. Signup and view all the answers

Which command confirms the VLAN configuration on all switches at once?

send commands to all devices Signup and view all the answers

What does the DORA process stand for in relation to DHCP?

Discover, Offer, Request, Acknowledge Signup and view all the answers

What happens to the broadcast discover message in VLAN 10?

It is forwarded to all ports in VLAN 10. Signup and view all the answers

Study Notes

Implementing VLAN Trunking with 802.1q

Configuration of trunking between multilayer switches MLS1 and MLS2 uses 802.1q Ethernet trunks.
Initiate trunk configuration by utilizing the command show interface trunk to check any existing trunk interfaces.
On MLS1 and MLS2, initially, no interfaces act as 802.1q trunks.
Enter configuration mode on MLS1 with configure terminal and utilize interface range command to configure multiple interfaces simultaneously (Gig 0/1, Gig 1/1).
Set trunk encapsulation to dot1q using switchport trunk encapsulation dot1q on both switches.

Configuring VLANs

Change the interface mode to trunk using switchport mode trunk.
Ensure that VLANs exist on both switches; create VLAN 10 (HR) and VLAN 20 (Sales) on MLS2 to match with MLS1.
Use the command send commands to all sessions for consistent VLAN configuration across switches.

Enabling Interfaces

Enable interfaces using no shutdown command to ensure they are active and ready for trunking.
Verify trunk interface status again using show interface trunk, checking for active 802.1q trunks on both switches.

DHCP Process and Troubleshooting

Understand that DHCP Discover messages initially sent by a client on VLAN 10 need proper tagging for effective handling.
Highlight the importance of VLAN tagging during the DORA process; untagged packets indicate misconfiguration.
Identify the need to assign correct VLANs to interfaces with commands like switchport access vlan 10 for Gig 0/0 and switchport access vlan 20 for Gig 0/1 on MLS2.
Confirm the configuration through commands like show vlan brief and ensure operational status.

Resolving Interface Issues

If Layer 3 interfaces (SVIs) for VLANs are down, recreate them to activate functionality.
Monitor the network traffic using packet capture; observe DHCP Discovery messages to confirm they carry the correct VLAN tag in captured frames.

Summary of Key Concepts

Ensure switch ports are associated with the correct VLANs for successful communication.
Maintain active Layer 3 interfaces to facilitate routing and DHCP responses efficiently.
Trunking allows for the passage of VLAN traffic between switches, tagging frames appropriately for correct delivery.
Utilize troubleshooting skills to identify configuration issues that may impact networking functions.

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Description

This quiz covers the implementation of trunking with 802.1q Ethernet trunks between MLS1 and MLS2, including configuring Cisco Systems' multilayer switches. The quiz focuses on the commands and configuration required for this process.