In this lesson,
we're going to cover VLAN configurations.
Virtual local area networks or VLANs
are a fundamental aspect
of our modern network designs and architecture
because they offer us with more flexibility,
improved performance, and enhanced security
over our traditional networks.
To effectively use A VLAN though,
you must properly configure it.
So in this lesson,
we're going to take a look
at some common interface configurations
that you should consider
when setting up or managing a VLAN in your network,
including 802.1Q tagging,
the native VLAN,
a voice VLAN, link aggregation,
and speed and duplex configurations.
Now, first we have 802.1Q tagging.
802.1Q tagging is a crucial element in VLAN configurations.
802.1Q tagging, also known simply as VLAN tagging,
refers to the IEEE standard
that facilitates the management of multiple VLANs
on a single network.
VLAN tagging works by inserting a VLAN tag
into an ethernet frame
to enable your switches to identify
and forward the frames to the proper VLAN.
Each tag is going to contain a VLAN identifier or VID,
which is used by our switches
to distinguish one VLAN from another.
This will allow for trunking to occur as well.
Now, when I talk about trunking,
trunking is just the transmission of traffic
from different VLANs
across the same physical network infrastructure
while keeping that traffic from each VLAN
separate and secure.
In many large enterprise networks,
we're going to use 802.1Q tagging
to create logical separations
between our different departments,
like human resources and accounting,
so that each one is put into a separate VLAN
and they can each have different security measures
put into place to protect each department
against threats that are specific to their daily work.
Whenever a data packet originates
from the HR department's network, for example,
it's going to be tagged with a unique VLAN ID
for the human resources VLAN
as that data leaves the departmental switch.
Whenever these packets traverse the network
through the shared switches and links,
the 802.1Q tag that was applied to the frame
will ensure that they remain isolated
from the finance department's traffic as well.
Similarly, the finance department's traffic
will also be tagged with a different VID
to signify that it belongs to the finance VLAN instead.
This type of tagging
is going to help to maintain data segregation
as well as enabling the use of our network resources
by allowing multiple VLANs to coexist
on the same physical network infrastructure devices.
Second, we have the native VLAN.
The native VLAN is the one VLAN on a trunk port
that does not get tagged with a VLAN identifier
when the frames are being passed over that trunk link.
Essentially, this is the default VLAN for untagged frames,
and you'll often hear the native VLAN
also called the default VLAN because of this.
Whenever a switch received an untagged frame
on a trunk port,
it's going to assign that frame to the native VLAN.
Now, if you're transferring data from multiple VLANs
over a single trunk link between your switches,
you're also going to need to interact with devices or networks
that may not understand VLAN tags.
And in this case,
you can assign that type of data to the native VLAN
to increase your capability and compatibility.
So let's pretend that you have a network
that you're going to be designing
that has to support some older legacy network devices
that simply can't support VLAN tagging.
These legacy devices are going to be sending untagged traffic
to your newer, more modern network switches.
And when the traffic reaches those modern switches,
the trunk port on those modern switches
is going to be designed to assign every piece of traffic
to a specific VLAN.
Since the data received
from the legacy switches is untagged,
the modern switch will simply tag that traffic
as part of the native VLAN when it's received,
and then it'll continue to pass that traffic
along the native VLANs default pathway.
For example, if your modern switch uses VLAN 10
as its native VLAN,
any untagged traffic coming into the trunk port
is automatically going to be assigned to VLAN 10.
This setup ensures seamless communication
between our older legacy equipment
that doesn't support VLANs
and our newer more modern VLAN capable switches.
This helps to maintain our network functionality
without requiring us to do a complete overhaul
of all of our existing network infrastructure.
Now, for the native VLAN to work though,
you have to ensure that the native VLAN
is consistently configured
across all of your interconnected switches
to avoid misrouting your untagged traffic.
By default, the native VLAN is usually defined as VLAN one,
but most cybersecurity experts will recommend
that you rename the native VLAN to something else
like VLAN 10 or VLAN 100
in order to prevent an attacker
from successfully implementing what's known
as a VLAN hopping attack.
Third, we have a voice VLAN.
Now, a voice VLAN is a specialized VLAN
that's dedicated to your voice traffic,
particularly voiceover IP
or VoIP traffic within your network.
The primary purpose of the voice VLAN
is to ensure that the quality
and reliability of your voice communications is insured
by separating voice traffic out
from your regular data traffic.
This segregation by traffic type
is essential because voice traffic is highly sensitive
to delays and packet loss.
By setting up a dedicated voice VLAN,
we can configure our switches
to prioritize the voice traffic
by enabling the application of quality of service
or QOS policies
to optimize our voice communications
and to ensure that we maintain higher levels of clarity
and better continuity for our voice calls,
even when our network is under heavy loads.
For example, in a business environment
where both data and VoIP services are used extensively,
implementing a voice VLAN
can significantly improve your call quality.
When you set up a network device like your VoIP phones
and your conference room video teleconference
or VTC systems,
you need to configure them
to send their traffic through the voice VLAN.
This way, whenever an employee places a VoIP call,
the data packets from that call
are going to be tagged for the voice VLAN,
and this VLAN will have its traffic prioritized
over other types of data traffic like email or web browsing.
By doing this,
you can ensure that the voice packets
are given precedence in your network
so that the latency, jitter, and packet losses
are going to be reduced.
Fourth, we have link aggregation.
Now, link aggregation,
also known as port channeling or bonding,
is a method used in networks
to combine multiple network connections together
into a single logical link.
This link aggregation technique
enhances the bandwidth capacity
and it provides redundancy
for higher levels of network availability.
By aggregating, bonding,
or teaming our network lines together this way,
we can combine multiple network links
so that our data can be distributed across multiple links
in an organized manner
to utilize the combined bandwidth
of all of those combined links.
Now, additionally,
link aggregation will help
to provide redundancy and resiliency
because our network traffic can continue to flow
over the remaining links
to minimize the risk of a complete network outage
if one of your links in the aggregated links
happens to fail.
Now, link aggregation is commonly used
to support trunking lines between our switches as well.
After all, if I have a 24 port one gigabit per second switch
and we're only using one gigabit per second network uplinks
between each of our switches,
this will cause a bottleneck in our network
because these trunk lines can quickly become overloaded.
Instead, if you have a 24 port switch
with one gigabit per second switch ports on it,
I recommend that you use
either a 10 gigabit per second fiber link
between your switches,
or you use link aggregation across four switchboards
to provide at least an aggregated
four gigabits per second network link between your switches
for your VLAN trunks to use.
For example, if you're working in a data center
where consistent high speed connectivity
is crucial for your server operations,
you probably want to configure the use of link aggregation
with all of your switches.
By implementing link aggregation,
your server can be connected to a switch
via multiple ethernet cables
to effectively multiply the available bandwidth
to that server.
So if we're able to aggregate
four one gigabit per second links together,
we're actually creating a total bandwidth
of four gigabits per second for us to use.
This aggregation not only provides
a high throughput connection
that's suitable for intensive data operations,
but also ensures network resilience
because our server can maintain its network connection
to its remaining links
if one of those four links happens to fail.
This type of redundancy
is particularly critical in environments
where downtime will have a significant operational
or financial implications on your business.
Fifth, we have speed and duplex configurations.
Now, speed and duplex configurations in a network
are the settings that are used to determine
the rate at which data is going to be transmitted
and the mode of communication between your network devices.
Now, when we talk about speed,
we're referring to the rate of data transfer,
and this is typically going to be measured
in megabits per second or gigabits per second.
Now, duplex, on the other hand,
refers to how data is going to be sent over that connection,
and this can either be half duplex or full duplex.
In half duplex mode,
data transmission and reception cannot occur simultaneously,
and instead, your device can either send or receive data,
but it can't do both at any given time.
Now, this works like walkie-talkies
that you may have used back when you were a kid.
If you were talking,
your friend on the other end had to listen.
Then when they wanted to talk,
you had to stop and listen before you could transmit again.
Now in full duplex mode, on the other hand,
this allows for a device
to send and receive data simultaneously.
Full duplex mode
will help to increase our overall transfer speed
because it effectively doubles our network capacity
when compared to half duplex mode.
Now, speed and duplex configurations
are something that network administrators
will often overlook,
and it can really slow down your network's performance
if you don't ensure it's properly configured.
For example, let's assume
that you have a high performance server
that's connected to one of your network switches.
If that server is capable
of handling a one gigabit per second full duplex connection,
but the device was incorrectly configured
to operate at 100 megabits per second,
using a half duplex mode connection,
this misconfiguration will significantly limit
your data throughput
to one 10th of the service capacity
because it's configured to send and receive data
at only a hundred megabits per second
of that one gigabit per second
that the server could support
at its maximum transmission speed.
Additionally, if that device is configured for half duplex,
even though it could support full duplex,
this misconfiguration will restrict our communication
to one way at a given time,
and this will lead to more network congestion
and performance issues
that could effectively half the amount of speed
that we're going to see out our networks.
So by correcting the misconfiguration
of the server speed and duplex settings
to match its maximum capabilities,
we're going to be able to ensure
that we're receiving optimal network performance
for all of our devices.
Now, most devices are going to be configured out of the box
to support what's known as auto-negotiation.
Auto-negotiation is commonly used
when devices automatically select
the highest performance settings that they have in common.
However, in certain situations
such as when you're using legacy equipment
or specific performance requirements,
you may want to use manual configurations instead
to be able to achieve the desired network efficiency
because auto-negotiation can sometimes lead to lower speeds
and wrong duplex settings being negotiated
because the devices aren't being configured
for their maximum settings like they should be.
So remember, configuring VLAN is a critical skill
for network professionals.
You have to understand 802.1Q tagging,
the native VLAN,
a voice VLAN, link aggregation,
and speed and duplex configurations
if you want to be able to design
and manage efficient, secure, and robust networks.
802.1Q tagging is a network standard
that adds a VLAN ID to ethernet frames
to help efficiently manage and route data
across multiple virtual local area networks or VLANs
on your same physical network.
The native VLAN is going to be the default VLAN on a trunk port
that carries all of your untag traffic
to ensure compatibility with devices
that do not support VLAN tagging
such as older legacy devices.
A voice VLAN is a dedicated VLAN on a network switch
that's configured to prioritize
and segregate voiceover IP traffic
to ensure its quality and reliability
of those voice communications.
Link aggregation is going to combine
multiple physical network connections
into a single logical connection
that will increase the bandwidth
and provide redundancy for us.
And then we have speed and duplex configurations,
which are going to be used to determine
the rate of data transmission
in either megabits per second or gigabits per second,
and the mode of communication
that is going to be used between the network devices
like full duplex
for simultaneous sending and receiving of your data
or half duplex for devices that will alternate
between sending and receiving data at any given time.