Hub, Bridge, Switch, Router - Network Devices - Networking Fundamentals - Lesson 1b
Summary
TLDRThis video script delves into the fundamentals of networking, explaining how data flows through the internet. It covers the roles of network devices like hosts, IP addresses, networks, repeaters, hubs, bridges, switches, and routers, emphasizing their functions in data transmission and network connectivity.
Takeaways
- 🌐 The purpose of the module is to teach how data flows through the internet.
- 🔌 A network is created when two computers are connected using a wire, and data signal decay occurs over greater distances.
- 🔁 A repeater's function is to regenerate signals to allow connectivity over longer distances.
- 🔄 A hub is a multi-port repeater used to connect multiple devices, but it doesn't filter traffic, causing all devices to receive all data.
- 🚦 A bridge connects two network segments and learns which hosts are on which side, containing traffic to necessary segments.
- 🔄 A switch is like a hub and bridge combination, facilitating communication within a network on a per-port basis.
- 🏢 Networks are logical groupings of hosts with similar connectivity needs, sharing the same IP address space.
- 🔄 Routers facilitate communication between different networks and are essential for internet connectivity.
- 🛡️ Routers provide traffic control points and are used for applying security policies and traffic filtering between networks.
- 🗺️ Routing tables in routers store the networks they are aware of and guide the data flow to the appropriate interfaces.
- 🌐 The internet is a network of routers that direct data flow between different networks globally.
Q & A
What is the main purpose of a repeater in networking?
-A repeater's main purpose is to regenerate signals that come in on one end and output them on the other side, allowing for the connection of devices over greater distances by overcoming signal decay.
Why do we need a hub in a network?
-A hub is needed to address the scalability issue of connecting multiple hosts directly to each other. It acts as a multi-port repeater, allowing all connected hosts to have connectivity with each other.
What is the fundamental problem with using a hub for connecting multiple hosts?
-The fundamental problem with using a hub is that it broadcasts data to all connected ports, meaning every host receives a copy of every transmission, which can lead to inefficiencies and security concerns.
How does a bridge help in mitigating the issues of a hub?
-A bridge helps by learning which hosts are connected to each of its ports and only forwarding packets to the necessary side, thereby containing communication to relevant networks and reducing unnecessary traffic.
What is the primary function of a switch in a network?
-A switch's primary function is to facilitate communication within a network by learning which hosts are connected to each port and forwarding packets only to the necessary ports, thus optimizing traffic flow.
How does a switch differ from a hub in terms of handling network traffic?
-Unlike a hub, which broadcasts traffic to all ports, a switch forwards traffic only to specific ports where the intended recipient host is connected, thus preventing broadcast storms and improving network efficiency.
What is the role of a router in a network?
-A router's role is to facilitate communication between different networks. It acts as a traffic control point, allowing for the application of security policies and traffic filtering, and directs data to the appropriate network based on its routing table.
Why are routers essential for connecting to the internet?
-Routers are essential for connecting to the internet because they provide a gateway for local networks to reach the global network of networks. They manage the flow of data to and from the internet based on their routing information.
What is a routing table and how is it used by a router?
-A routing table is a data structure that stores the networks a router knows about and the paths to reach them. Routers use this table to determine the best interface to forward packets to their destination networks.
How does a router create a hierarchy in networks?
-Routers create a hierarchy in networks by connecting different subnetworks and managing the flow of traffic between them. They direct data packets through the most efficient paths, creating a structured flow from local to global networks.
What is the difference between routing and switching in the context of network devices?
-Routing refers to the process of moving data between networks, while switching is the process of moving data within a network. Routers primarily perform routing, and switches primarily perform switching, but many network devices can perform both functions.
Outlines
🌐 Understanding Network Devices and Data Flow
This paragraph introduces the second part of a lesson on network devices, focusing on switches and routers. It emphasizes the importance of understanding how data flows through the internet. The discussion starts by reviewing the concepts of hosts, IP addresses, and networks from the first part of the lesson. The script then delves into the limitations of direct host-to-host connections due to signal decay over long distances, highlighting the role of repeaters in regenerating signals. The introduction of hubs as multi-port repeaters and their limitations in managing data traffic among multiple devices is also covered. The paragraph concludes with an explanation of bridges, which help contain communication within specific networks by learning which hosts are connected to each side of the bridge.
🔌 The Role of Switches in Network Communication
This paragraph builds on the previous discussion by introducing switches as a combination of hubs and bridges. Switches allow multiple devices to connect and learn which hosts are connected to each port, facilitating communication within a network. The formal definition of a switch is provided, emphasizing its role in facilitating communication within a logical grouping of hosts that require similar connectivity. The paragraph also discusses the concept of IP address spaces and how different devices, such as those in a home Wi-Fi network or a school classroom, can belong to the same network. The importance of separating devices with different connectivity requirements into different networks is highlighted, with switches facilitating communication within these networks. The paragraph concludes with an introduction to routers, which are necessary for communication between different networks, and their role in providing traffic control points and security policies.
🌐 Routers: Facilitating Communication Across Networks
This paragraph focuses on routers and their primary purpose of facilitating communication between networks. It explains how routers learn which networks they are attached to by having an IP address in each network, serving as gateways for hosts to exit their local network. The concept of routing tables, which store the networks a router knows about, is introduced. The paragraph illustrates how routers create a hierarchy in networks and IP addresses, connecting different routers to facilitate communication across various networks. The script uses the example of the Acme Corporation's offices to explain how data flows across the internet, with routers directing traffic through a series of routers to reach the destination. The paragraph concludes by emphasizing the role of routers in creating the internet's structure and the importance of understanding routing and switching in the context of various network devices.
📚 Engaging with the Networking Fundamentals Course
In this final paragraph, the script shifts from technical explanations to a more personal and engaging tone. The instructor invites viewers to participate in shaping the course by suggesting topics they would like to see covered. The paragraph encourages viewers to like, subscribe, and share the video as a way of showing appreciation for the content. The instructor expresses gratitude for the viewers' engagement and looks forward to their feedback in the comments section. The paragraph concludes with a teaser for the next lesson, which will provide a practical perspective on the OSI model, laying the foundation for understanding how various network devices enable data flow through the internet.
Mindmap
Keywords
💡Network
💡Host
💡IP Address
💡Repeater
💡Hub
💡Bridge
💡Switch
💡Router
💡Gateway
💡Routing Table
Highlights
Introduction to the second part of a lesson on network devices, focusing on switches and routers.
Explanation of signal decay over long distances and the role of repeaters in regenerating signals.
The concept of a network and the impracticality of connecting hosts directly to each other for scalability.
Introduction of hubs as multi-port repeaters to facilitate communication among multiple hosts.
The issue of data traffic in hubs where all hosts receive each other's data.
Role of bridges in containing communication to relevant networks and learning host connections.
Definition and function of switches as devices that combine the features of hubs and bridges.
Switches' ability to facilitate communication within a network on a per-port basis.
The concept of a network as a logical grouping of hosts with similar connectivity requirements.
Differentiation of networks within an organization based on connectivity needs.
Introduction of routers as devices facilitating communication between different networks.
Routers' role in traffic control and security policy application at network boundaries.
Explanation of routing tables and how routers use them to direct traffic to appropriate networks.
The concept of a gateway as the exit point for a host to communicate with a different network.
Hierarchy in networks created by routers and the flow of data across different networks.
Understanding the broader definition of routing and switching in the context of various network devices.
Overview of other network devices like access points, firewalls, load balancers, and their roles in routing or switching.
Conclusion of the lesson with a summary of the key takeaways on network devices.
Invitation for feedback on course content and an encouragement to like, subscribe, and share the video.
Transcripts
hello welcome to the second part of our
lesson on network devices
this is the first lesson from the first
module of my new course on networking
fundamentals
the purpose of this module is to teach
you how data flows through the internet
in part one of this lesson we discussed
the concepts of a host
an ip address and a network if you
haven't watched that video go ahead and
pause this video right now and watch the
first video
there'll be a link in the description in
this video we're simply going to
continue right where we left off
now the main idea we want to teach in
this video are these last two devices
switches and routers but we can't really
understand those
until we understand where we've come
from so we have to start there
in the last video we unpacked the idea
of a network we identified that a
network is created anytime you connect
two computers to each other using a wire
one thing to understand about sending
data across a wire is that it decays as
it travels greater and greater distances
if the two computers you're connecting
are in the same room then you don't
really have to worry about it
the decay will still occur but the
signal will still get through and
therefore
connectivity between these hosts is
still attained if
however these hosts span greater
distances maybe
you're connecting two computers on
opposite sides of a building or even in
two different buildings
then you might have a problem if the
signal decays before it gets the other
side
then these two hosts cannot share data
in those cases what you need is a
repeater a repeater
is a device whose sole purpose is to
regenerate signals
anything that comes in on one end simply
gets regenerated out the other side
this allows you to connect devices
together which span greater distances
so far we've been talking about
networking from the perspective of
connecting one host
directly to another host well if you add
a third host
you now have to connect that host to all
the other hosts which you've already
established and if you add a fourth host
you now have to connect this fourth host
to all the hosts that already exist
and again if you add a fifth host you
now have to connect this fifth host
to every host that has already been
connected as you can see
connecting host directly to each other
simply doesn't scale
instead we created devices which we
could put at the center of every network
and connect all the hosts to those
devices
and these devices would then handle
funneling communication between these
different hosts
the benefit to these types of devices is
that if a sixth host gets spun up
it's very easy to simply connect it once
to that device and now it has
connectivity to every host that has
already existed
that's what all of these are and the
first of these types of device that
we're going to discuss
is known as a hub a hub
is nothing more than a multi-port
repeater
earlier we discussed repeaters and we
said all they do is regenerate signals
hubs do the same thing except they do it
across multiple ports
for example if these two hosts over here
need to communicate
one of them sends a packet to the other
it'll hit the hub and the hub will
simply duplicate that packet and send it
out all remaining ports
that allow what this guy sends to arrive
over here
this fixes the scale problem hub is the
first device that allows us to connect
multiple devices in the center and now
all of them have connectivity to each
other
but as you can probably see the problem
with the hub is that everybody receives
everybody else's data
these two hosts over here which are
uninvolved in the communication between
these two hosts
are receiving a copy of everything they
send
which brings us to bridges here
we have two sets of hosts all
interconnected using a hub
and a bridge is meant to sit in between
hub-connected hosts
bridges by definition only have two
ports one port facing one set of
hub-connected devices and another port
facing the other set of hub connected
devices
bridges will also then learn which hosts
are on which
side of the bridge this would allow the
bridge to contain communication
to only the side that is necessary for
example
if these hosts again need to speak to
each other
when they send data to each other
through that hub the hub is of course
going to simply regenerate that signal
at all ports
and notice that the bridge can be
getting a copy of that packet
but the bridge knows that the other
green host is on this side of the bridge
and therefore the bridge isn't going to
bring that packet to the other side
the bridge is the first type of device
that helps contain packets only to their
relative networks
on the other side if these hosts need to
speak to each other
they can also send packets to each other
through their hub and once again the
bridge will not let those packets bleed
into the other side because it knows
the yellow devices exist on the right
hub
and of course if this device needs to
send something to this device
the bridge is going to know that that
traffic is going to have to cross the
bridge
and the bridge will allow that packet to
traverse to the other side
the main takeaway is understanding that
bridges can learn which hosts are
connected
on either side of the two ports of the
bridge now this
finally brings us to switches switches
are sort of like a combination
of hubs and bridges they are like hubs
in the sense that many devices can
connect to the switch
and they are like bridges in the sense
that they can learn which hosts are
connected to each port
the main difference is that they're
doing it on a per port basis
which means if these two hosts want to
speak to each other
the switch will know that the only ports
that need to receive this traffic
are the two that are connected to those
green hosts and will keep that
communication contained to just
those ports moreover if these two hosts
want to speak to each other
the switch will again make sure that
that communication only flows between
the relative ports
so this is how a switch is like a
combination of a hub and a bridge
the formal definition of a switch that
we want to use is that a switch is a
device
which facilitates communication within a
network
earlier we defined a network as a
logical grouping of hosts which require
similar connectivity which means
all of these devices over here all
belong to the same
network moreover networks
all share the same ip address space
which means this network owns all the ip
addresses which start with
192.168.1.anything
and this host's identity is the ip
address 192.168.1
dot and this host would be 192.168.1.66
and this set of devices could very
easily represent
all the different hosts on your home
wi-fi network
maybe this device is your printer and
this device is your laptop
and this device is your mobile phone and
so on
or maybe this network and these devices
represent all the pcs that might exist
within a particular classroom
of the school network or maybe even
further all these devices represent
hosts that exist in the sales team
of the london office of the acme
corporation
one way or another since all these
devices are connected with a switch
they all belong to the same network now
let's go back to that example of the
school network
we said that the school likely has many
different classrooms
and each of those classrooms belong to
their own network
which means this would be a more
accurate representation of the school
network we would have classroom two
owning that ipspace and classroom three
owning that ipspace
now the reason you might want to
separate these two sets of devices into
their own network is because they might
have different connectivity requirements
for example maybe these computers over
here
all belong to the biology classroom and
all they need is simple internet
connectivity
but maybe these computers over here
belong to the computer science classroom
and they not only need internet
connectivity but also access to various
cloud resources
to do their studies well since these
computers have different connectivity
requirements than
these computers it's a good idea to
separate those out into separate
networks
now in both cases we can still use
switches to facilitate
all the communication within the
networks meaning
this switch can handle all the
communication between these three
hosts and this switch can handle all the
communication
between these three hosts
but what happens if this host down here
wants to speak
to this host on a different network
well if a switch can only facilitate
communication within
a network we would need another type of
device to handle the communication
between networks and that device would
be
a router a router is a device whose
primary purpose is to facilitate
communication
between networks at the very least
you're going to need that router to
connect you with the ultimate network of
networks
known as the internet so let's unpack
this further
routers provide traffic control points
between
networks let's say we wanted to limit
the traffic that could go from this pc
to this pc
well since these two pcs aren't separate
networks all that traffic
has to flow through the router creating
a great place
to add security policies or traffic
filtering or even redirecting that
traffic elsewhere entirely
since routers sit on the boundary
between networks
they provide a logical location to apply
security policies
this type of security filtering isn't
traditionally available on switches
these days there are modern switches
that can do such filtering
but it is generally accepted that the
devices sitting on the same network
don't typically need filtering for
traffic traveling within the network
if you had devices that needed different
types of connectivity you'd want to
place them in different networks
the network boundary is what is meant to
be the logical separation of devices
the way routers work is that they learn
which networks that they are
attached to meaning this router is going
to learn that on this interface it's
connected to the 172 16.20 network
and on this interface it's connected to
the 172 1630 network
and out here is the direction to go to
the internet
the knowledge of each of these different
networks is known as a route
and all these routes are stored in what
the router calls a routing
table a routing table is therefore
all the networks that a router knows
about and the router is going to use
this routing table in order to funnel
traffic
out the appropriate interface now
when we say a router learns which
networks they are attached to
what we mean is that a router has an ip
address
in every network that they're attached
to for example
when this router is attached to this
network it is given
an ip address in that network this
interface's identity
is the ip address 172.16.20.1
and this interface's identity is the ip
address 172
16.30.254
this ip address is going to serve as
what's known as a gateway
a gateway is a host's way out of their
local network
for example this host over here has the
ip address 172
16.20.33 but if that host
wants to speak to something on a
different network it knows it's going to
have to go
through a router and the ip address for
that router is stored as that host's
default gateway
notice this host has a default gateway
of 172.16.20.1
that's this interface ip address of that
router
now if we go a step higher than that
routers are actually what create
the hierarchy in networks and ip
addresses that we discussed in the prior
sections of this lesson for example the
new york office of the acme corporation
that had all the different teams that
each had their own ip networks
well each of those networks are
connected to different routers
and each of those routers are then
connected to another router
and if a host in the sales team wants to
speak to a host on the marketing team
it's going to use its gateway which is
its closest router ip address
which is then going to send the packet
to the next router to the next router
and then finally to the host on the
marketing team
the tokyo office of the acme corporation
is likely going to have a similar setup
and both of these routers are then
likely going to connect to the internet
the internet is nothing more than a
bunch of different routers itself
meaning if a host on the marketing team
wants to speak to a host on the
engineering team in tokyo
that host will send the data to the
router which will send the data to the
next router
which will send it through all the
routers on the internet which will
finally send it to the tokyo router and
finally to the engineering team
that is how data is going to flow across
the internet
and that is the role that routers play
in making that possible
now the last idea i want to leave you
with actually involves pulling back the
definition of switches as well
there's something important you have to
understand about what we've defined as
routers and switches
route ding is the process of moving data
between
networks a router as we have described
it
is simply a device whose primary purpose
is to perform
routing in the same way switching
is the process of moving data within
networks
and a switch as we have described it is
a device whose primary purpose
is switching the reason i bring that up
is there are many other types of network
devices that exist out there
access points firewalls load balancers
layer 3 switches proxies
and there's even devices that only exist
in the cloud like virtual switches and
virtual routers
one way or another all these devices are
going to perform
routing or switching or both so later on
in this module when we describe
what a router does or what a switch does
what we are actually describing is what
any device does that implements routing
or any device does that implement
switching
and with that we close our lesson on
network devices
in part one of this lesson we unpacked
hosts
ip addresses and networks and in part
two
we continued that discussion by
illustrating repeaters
hubs bridges switches and routers
in the next lesson we're going to give
you a practical perspective on the osi
model
this will lay the foundation to
understand what all of these devices do
to enable data flowing through the
internet
but that wraps up this lesson your main
takeaways are on the slide right now
i hope you enjoyed this lesson i want to
thank you for watching
and we'll see you in the next one
hey youtube i hope you enjoyed that free
lesson for my new course on networking
fundamentals
i'll be releasing the entire first
module for free here on youtube
i want this course to be the ultimate
networking fundamentals course and since
i'm still scoping out the outline you
could have a say in what topics will be
covered
let me know in the comments below what
subjects you want included in this
course
otherwise remember to like and subscribe
and of course if you learned something
from this video the best way to thank me
is to share this video
it's a small act of gratitude but one i
appreciate greatly
i hope you enjoyed this lesson i want to
thank you for watching and we'll see you
in the next one
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