Podcast
Questions and Answers
What is a primary benefit of VLANs in network administration?
Which of the following is NOT a common use case for VLANs?
What is a potential security concern with VLANs?
What can quality of service schemes optimize on trunk links?
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Which of the following network technologies has VLAN capabilities?
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Why was Ethernet limited in scaling up?
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What was the speed of Ethernet in the early experiments?
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What was the estimated total bandwidth of the telephone network?
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Who addressed the problem of scaling up Ethernet networks?
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What is the primary purpose of VLANs?
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What does VLAN stand for?
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At which OSI layer do VLANs operate?
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What is the purpose of VLAN tagging?
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What is the benefit of using VLAN trunks?
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What is the purpose of network architects setting up VLANs?
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What is the function of routers between VLANs?
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What is a benefit of VLANs in terms of network management?
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What is the purpose of link aggregation in VLAN trunks?
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What was the main issue with using IP routing to connect multiple Ethernet networks together?
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What did Sincoskie reinvent while looking for alternatives to IP routing?
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What is required to connect multiple Ethernet networks in a fault-tolerant fashion using switches?
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What is the purpose of the VLAN tag in an Ethernet frame?
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What is the result of sending a mix of different frame colors in a multitree bridge?
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What is the IEEE standard that describes Ethernet VLANs?
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What is the purpose of the IEEE 802.1ad standard?
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Why did Sincoskie invent VLANs?
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What is the term used to describe the VLAN tag in an Ethernet frame?
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What is a trunk in the context of VLANs?
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What is the primary purpose of a router in a VLAN?
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Why is tagging necessary when extending a VLAN port group to another device?
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What is the most commonly used protocol to support VLANs today?
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Why are VLAN port assignment charts or diagrams necessary in wiring closets?
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What type of ports do trunks typically run between?
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What is the purpose of the IEEE 802.1 working group's VLAN multiplexing method?
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What is a potential issue with switches in wiring closets?
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What is a common scenario where tagging is used in VLANs?
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What is used as a label in VLAN cross connect (CC or VLAN-XC)?
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What is the command to create a VLAN?
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What is the command to name a VLAN?
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What is the command to configure an interface as an access port?
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What is the command to assign a VLAN to a port?
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What is the command to configure multiple ports for a VLAN?
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What is the command to verify the VLAN configuration?
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What happens when you try to assign a VLAN that does not exist?
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What is the default VLAN name for VLAN 1?
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Study Notes
VLAN Concept and Introduction
- A Virtual Local Area Network (VLAN) is a broadcast domain that is partitioned and isolated in a computer network at the data link layer (OSI layer 2)
- VLANs work by applying tags to network frames and handling these tags in networking systems, creating the appearance and functionality of network traffic that is physically on a single network but acts as if it is split between separate networks
- VLANs can keep network applications separate despite being connected to the same physical network, without requiring multiple sets of cabling and networking devices to be deployed
VLAN Implementation
- To subdivide a network into VLANs, one configures network equipment
- Simpler equipment might partition only each physical port, while more sophisticated devices can mark frames through VLAN tagging, allowing a single interconnect (trunk) to transport data for multiple VLANs
- VLANs can be used to partition a local network into several distinctive segments, such as production, voice over IP, network management, storage area network (SAN), guest internet access, and demilitarized zone (DMZ)
- A common infrastructure shared across VLAN trunks can provide a measure of security with great flexibility for a comparatively low cost
VLANs Benefits
- VLANs address issues such as scalability, security, and network management
- VLANs provide the flexibility to adapt to changes in network requirements and allow for simplified administration
- VLANs can keep network applications separate despite being connected to the same physical network
- VLANs can optimize traffic on trunk links for real-time or low-latency requirements
VLAN History
- Dr. W. David Sincoskie invented VLANs by adding a tag to each Ethernet frame, allowing for improved scalability and bandwidth
- Sincoskie referred to this as a multitree bridge
- The concept of VLANs was first introduced in the 1980s, and the IEEE 802.1Q standard was published in 1998
VLAN Trunks
- A trunk denotes a network link carrying multiple VLANs, which are identified by labels (or tags) inserted into their packets
- Such trunks must run between tagged ports of VLAN-aware devices, often switch-to-switch or switch-to-router links rather than links to hosts
- VLAN port assignment charts or diagrams are necessary to indicate VLAN to port associations
VLAN Protocols and Design
- The protocol most commonly used today to support VLANs is IEEE 802.1Q
- Prior to the introduction of the 802.1Q standard, several proprietary protocols existed, such as Cisco Inter-Switch Link (ISL) and 3Com's Virtual LAN Trunk (VLT)
- VLAN cross connect (CC or VLAN-XC) is a mechanism used to create Switched VLANs, using IEEE 802.1ad frames where the S Tag is used as a Label as in MPLS
VLAN Configuration
- To configure a VLAN, one must login to the switch with console and type the commands to create a VLAN, name it, and assign it to ports
- The commands include
switch#configure terminal
,switch(config)#vlan 2
,switch(config-vlan)#name CSC
,switch(config-vlan)#exit
, andswitch(config)#interface fastEthernet 0/14
for a single port, orswitch(config)#int range fastEthernet 0/15-16
for multiple ports - The
show vlan brief
command is used to verify VLANs and their associated ports
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Description
This quiz covers the concepts of VLAN, Virtual Local Area Network, and its configuration. Understand how VLAN divides a single broadcast domain into multiple broadcast domains.