🚨📢 Update: *Full Course is Under Construction* --> pracnet.net/networking 👉👉 Enroll now for *discounted early access* to the course and a chance to help shape its content. 📺▶ Module 1 Playlist - Networking Fundamentals: th-cam.com/play/PLIFyRwBY_4bRLmKfP1KnZA6rZbRHtxmXi.html 💭💬 Join us on Discord: pracnet.net/discord _--- Original Comment below: ---_ *Full Course Status: Wait and See.* Hopefully you've come to realize that I put _a lot_ of effort into the content I create. I'm not a course creator that will simply turn on the screen recording and ramble, then call that teaching. I meticulously plan _every_ module and lesson to _maximize the learning and value_ for the student. To that end, it takes me a while to put together courses. If I'm going to dedicate the time, resources, and energy to putting this full course together, I need to know that there is enough interest in the full course. I'm rating that by how wide a reach this series achieves. *If you are interested in seeing the full course developed, then the best way to bring that to fruition is to spread the word about this content* . By itself it already conveys _a lot_ of value. So sharing even just the 7 lessons (13 videos) in this series will surely help whoever you share it with. Plus ... many online communities would greatly benefit from these videos. Think of all the Internet points you could acquire if you shared this series (karma, likes, follows, etc.) 😉 Use this link to share the full series: th-cam.com/play/PLIFyRwBY_4bRLmKfP1KnZA6rZbRHtxmXi.html Also, if you share it on Twitter or LinkedIn, please tag me =): twitter.com/ed_pracnet/ www.linkedin.com/in/eharmoush/
@@ultimatewarriorfrieza275 Just published Part 1 of the Router video a few days ago: th-cam.com/video/AzXys5kxpAM/w-d-xo.html Part 2 releases next week =)
Well, you probably don't understand it, but you helped quite a lot of people, and the thing you have done is something most people ask to be paid for, and their quality cannot compare with this. I am slowly watching every single one of your videos, and I just felt a need to say thank you for all these nice lessons. All the best to you sir!
Hey Danilo! Thanks for the kind note. I'm so happy you're getting a lot out of this series and you recognize the effort I put into making these as high quality as I could. Feel free to say hello on Discord! pracnet.net/discord =)
Albert Einstein once said: “If you can't explain it to a six-year-old, you don't understand it yourself.” And you are my dear teacher can take 2 years old and teach him everything you want no matter how complicated that subject is. That is an amazing gift you have. Bravo!!! Thank you so much Professor.
This means a lot to me, actually. That quote from Albert Einstein is the same quote I have on my mission statement: www.practicalnetworking.net/about/ Thank you for the note. Truly.
I have to say that I literally searched plenty of courses on TH-cam about networking fundamental , never come across a one that explains it this clearly, sorry for my bad english, thank you so much from the bottom of my heart 🙏
I learned more from this channel in a few days than I ever did in university in 4 years. You're amazing. Because of you, I have a better understanding of networking fundamentals. Thank you very much and keep up the good work. ❤
We didn’t have a networking class in college and this video explains networking so simply and intuitively. Thank you for demystifying computer networking.
Hi Kagame, thank you so much for the kind words and the donation. I'm honored to have helped with your networking journey and I'm sorry that a class like this wasn't available to you through your college! Your donation helps support the channel and the creation of more content. Thank you very much for your support =).
Omg 😮 you're simple and easy to listen too! Are you a teacher? If you're not you should be and they should pay you large! You're wonderful thank you for all of this at the end I'll donate and share!!! 10/5 stars you're brilliant!!!!!
Thanks for the kind words =) I was a professional trainer at one point. Never formally an academic teacher (although, I was a adjunct professor for one semester at a tech school) Either way thanks for your support and thank you for your shares =)
Hi Jonathan, thank you for your Super Thanks donation! Your generosity is greatly appreciated =) Donations like this directly aid in the development of more free, top-notch training content for all viewers. =) I'm humbled at your willingness to support the the channel. Thank you again. Cheers !
Really appreacited what this man did!! From the introduction to in depth lessons!! Omg this is brillant. You need to replace all the professors here in melbourne lol
Now that you've explained Networking Fundamentals in such a way... Could you tackle other things like Stock Market Calls and Puts?! Only partially kidding. Best internet instructor I've ever seen.
Excellent Content. I am glad that I came across the channel sooner or later. The WireShark captures on the website for concepts such as ARP, GARP on the website in addition to videos are icing on the cake. Please keep the videos coming, only a matter of time that you get more views and subscribers if you keep up the same level of quality in the future videos. Thanks for everything.
Thank you for the kind words. Glad you found these videos and the ARP/GARP articles on my blog helpful =). Hoping to get back at it with this series some time in the next four weeks. =)
Thank you for the superb quality of the information you've made available and for the effort involved in putting it together. I also really appreciate that this information is generic rather than product specific so we get to learn how the fundamentals work rather than having to filter out marketing hype.
Just finished the series, man these videos were so helpful! It's a shame that there is no more, but I appreciate all you have taught me in such a simple way. I Liked all the vids, and I will share with my friends. Thank you. :)
I just discovered your top notch videos. They're very easy to follow and understand, actually I find them very exciting. I'm binging on them. Thank you. I consider your style and content to be the best out of all on TH-cam.
THank you for the kind words, Sarinaht. Glad you are enjoying this series! Could you do me a favor? Do you mind sharing this video on Linked In, Reddit, Twitter, Facebook, or any other social media you use? As an independent creator, that would be an _enormous_ help, and I would appreciate it _greatly_ .
Thank you so much for these very clear and concise instructional videos! You are a truly a gifted teacher! Around 9:03 mark I think the 2nd MAC Address Table's last 2 entries will be swapped if I understood your explanations correctly i.e. entries would be in the order? 4 aaaa.aaaa.aaaa 6 bbbb.bbbb.bbbb 4 cccc.cccc.cccc 5 dddd.dddd.dddd
🚨📢 Update: *Full Course is Under Construction* --> pracnet.net/networking 👉👉 Enroll now for *discounted early access* to the course and a chance to help shape its content. 📺▶ Module 1 Playlist - Networking Fundamentals: th-cam.com/play/PLIFyRwBY_4bRLmKfP1KnZA6rZbRHtxmXi.html 💭💬 Join us on Discord: pracnet.net/discord _--- Original Comment below: ---_ *Full Course Status: Wait and See.* Hopefully you've come to realize that I put _a lot_ of effort into the content I create. I'm not a course creator that will simply turn on the screen recording and ramble, then call that teaching. I meticulously plan _every_ module and lesson to _maximize the learning and value_ for the student. To that end, it takes me a while to put together courses. If I'm going to dedicate the time, resources, and energy to putting this full course together, I need to know that there is enough interest in the full course. I'm rating that by how wide a reach this series achieves. *If you are interested in seeing the full course developed, then the best way to bring that to fruition is to spread the word about this content* . By itself it already conveys _a lot_ of value. So sharing even just the 7 lessons (13 videos) in this series will surely help whoever you share it with. Plus ... many online communities would greatly benefit from these videos. Think of all the Internet points you could acquire if you shared this series (karma, likes, follows, etc.) 😉 Use this link to share the full series: th-cam.com/play/PLIFyRwBY_4bRLmKfP1KnZA6rZbRHtxmXi.html Also, if you share it on Twitter or LinkedIn, please tag me =): twitter.com/ed_pracnet/ www.linkedin.com/in/eharmoush/
That's almost exactly my mission statement =). Knowledge that is easy to learn and easy to pass on. Glad you enjoyed it, Alice. www.practicalnetworking.net/about/
That's gonna be probably the only TH-cam tutorial series I will ever finish :) Incredible content and clear presentaton. I am currently doing Google's cybersecurity certificate and their module on networking can't even compare to yours. The plan is first finish to this series and then go back to the certificate.
Hi Vicki-Ann! Thank you for supporting the channel. Contributions like this help support the continued development of free content for everyone else. =) If anyone else reads this comment, you should thank Vicki-Ann for funding the free resources you are enjoying. =) Thanks again, Vicki-Ann !
Thanks for the kind words and all your comments. I enjoyed seeing them on all the video series you watched. So glad you enjoyed them. Wish you luck w/ your studies =). Cheers !
So in simple definition the difference between broadcast(ing) and flood(ing) is that: Broadcast is an intentional way of sending messages or packets to all the devices connected to the network, but flooding is a way of unintentionally or uncontrollably sending messages or data to all the connected devices in a network. In broadcasting the destination address is known while in flooding the destination is unknown. Real world example of these can be as follow: Broadcast : For example you are in a room and you intentionally speak loudly to everyone in the room so they can hear and understand you. Flooding: For example - you have a pipe and there is a leak in the pipe and the water spreads out of the hole and spreads unintentionally and uncontrollably across the room, and make the room wet. The same thing happen to network. I hope I made it clear and understandable......... give me a like for understanding this real world example of "Broadcast & Flood"
If the computer is disconnected from the port or does not communicate for a long time, or in case of changing the network card, the MAC address table entry is erased due to aging time? Does the Switch remove the MAC input because it has detected that the port is no longer connected or is the MAC input removed because the lifetime has expired (aging time counter)?
Both. If a switch detects the cable is disconnected typically it will purge the mac addresses associated with that port. Also, typically MAC address also age out if there is no activity from the host (5min is common, but probably each vendor has different values).
@@PracticalNetworking In case if I send a command to shut down a computer will the Switch be able to detect that the port is still connected even with the computer turned off and then the MAC will only be removed after the MAC lifetime expires? If the network cable is disconnected it will remove immediately because the Switch detected that the port is no longer connected is that it? Is there then such a difference?
Hello sir. great course. I have a question, why on the mac address in the green one, the cccc is the last one? it not should be one before? because the 4 port get the cccc, and only after its get the dddd back. Please if you can explain, Thank you
This is the kind of videos I was looking for to learn networking! Thanks a lot for this! I had a follow up question: 1. What happens to the MAC address mapping table when I disconnect a host from a switch and replace it with another host which has a different MAC address? How does the MAC Address Table (and ARP Cache) get refreshed ? Is there a retry on fail, or are the MAC Address Table (and ARP Cache) proactively refreshed on detection of a new hardware connected to the network ? Also, is there a networking fundamentals course (paid) that you have? I would love to learn more about networking fundamentals from you.
What happens when the MAC Address Table for Host D has been mapped out and the physical connection of Host D is moved from the green switch to the blue switch? Will the next packets from Host A to Host D be undelivered?
Great question! It shows you are really thinking about this stuff. Typically, when a device is disconnect, the switch will detect that a port is no longer connected and "forget" any MAC addresses learned on that port. So if Host D was removed, it's MAC entry would be purged from the green switch, and the next communication with a destination MAC of Host D would be flooded. But in your example, the Blue switch had no physical connection removed, so will continue to think that Host D exists out port 3... and will continue to forward packets that direction to (try to) reach Host D. This would occur until Host D sent _anything_ in which case the Blue switch will see traffic with a source MAC address of DDDD arrive on a different port, and will therefore update it's MAC address table. With nearly any computer these days, as soon as you are plugged in, software is attempting to speak on the network so this actually happens pretty much instantly (consider software/app updates, weather apps, location apps, email apps, etc... all of them are constantly speaking in the background).
6:27--> "the blue switch just did unicast flooding". I think the correct term is broadcast flooding since the switch send the frame wherever possible (I understand that switches don't cast, but I only try to convey the meaning...)
Hi Sir. Thank you for all your videos. I'm rewatching everything and I have a question. What happens to the MAC address table after you unplug the host from the switch? Will the switch automatically delete the entry related to that port in the MAC address table?
was going to edit my previous comment after I learned a bit more about MAC address table but it disappeared for some reason. The answer to your question is yes, when a host is disconnected from a switch, the entry related to that port in the MAC address table gets deleted.
Great video and really in depth explanation, i having difficulties to understand the Unicast frame and the Broadcast Frame, I grasped their terminology, but what i am struggling to understand is that, wont a Unicraft frame always use ARP protocol to determine where the traffic its going and so it can be added to the MAC address Table?? Thank you
9.35 : when port 3 has bbbb mac address, and when host c wants to sent to host d obviously port 3 has B's address so to find out host D 's address switch going to flood frames to all hosts ?
Nice video!!! I have one question. In the last video, you mentioned you said we need IP address of a switch when we are communicating something TO the switch but do not need IP address when we are communicating through the switch. What is the difference. I don’t understand in which cases we will be communicating to the switch. I am sorry if it sounds like a stupid question. I am actually unable to understand.
Hi @Practical Networking Shouldn't the second Switch have this MAT: 4. aaa 6. bbb 4. ccc 5. ddd Since it receives a new frame from an unknown MAC address, shouldn't it map CCC first before DDD? Regardless, I very well understood the concept on this video. Thank you!
great video!! but I want to ask you does the order in the MAC address matters? because what I got in order for green switch MAC address table was 4. aaaa, 6. bbbb, then 4. cccc (host C sent data intended to host d), finally 5. dddd. sorry if it's confusing I just want to make sure my understanding about this one. thanks!
Does a switch only flood ports that it does not have a MAC address assigned to? I guess probably not for the cases where a port might contain multiple MAC addresses?
No, they are different. Broadcast - send this frame to *everyone* on this network Multicast - send this frame to *everyone in a specific multicast group* on this network Unicast - send this frame to *one other person* on this network I know you didn't ask for Unicast, but the definition helps clarify how Multicast is "in between" Broadcast and Unicast. HTH
Is it possible that a switch, instead of storing multiple mac addresses for one port(indicating that that port is likely connected to another switch), that an implementation might overwrite? Just wondering if that's a valid implementation. I'm speculating about this next part but if this is done then the next time another device tries to send to the MAC that was overwritten that it would just unicast flood again.
It's possible, but that wouldn't scale. There are hierarchies of switches that might have 1000s of hosts on a single port. If each is overwriting the last, it would cause 999 hosts to be unicasting flooding at any given time.
Hi, when u say switch can flood and learn , then why at all ,there is a need of sending ARP request. ? just send the frame from host A , switch will learn the from next time.
I have a question. When the green switch forwards the frame to the blue switch, why doesn’t it change the source max to its own mac, instead of keeping the source mac as the mac of device A? Lovely videos btw ❤️
Switches were intended to be transparent -- almost like an extension to the wire itself. So they make no modifications of the packet/frames that are sent through them. Glad you enjoyed it =)
I have a small question. From 5:14 the network that both switches using is the same right? Since switch communicates within network and router are for foreign network. Hope my question is clear enough to understand.
7:01 why doesn't the switch doesn't perform ARP at this point, to save itself having to broadcast the unicast frame ? isn't it safer aswell since you are not sending private information to hosts ??
@9:33, I got the solution as: 1 aaaa 4 aaaa 3 bbbb 6 bbbb 2 cccc 4 cccc 3 dddd 5 dddd Is this incorrect? I could see that in your solution the order between 4cccc and 5dddd in mac address table 2 is the reverse of mine. Kindly suggest.
What the host sends is independent of what the switch knows. If the host knows the MAC, it can sent a Unicast frame. If the host doesn't know the MAC, it _must_ send an ARP request. But remember the Switch is completely independent. Consider if the switching path changes _after_ the host already learned the MAC address. Then the new switch might not know the destination MAC and might resort to Unicast flooding. hope this helps =) Glad you've enjoyed this series!
This differs declaring the port as a switch or using the port suggested for it? I think not. Or in many Cisco switches are a yellow one or 2 or 4 for it. With special cables. In the 9300 cascading is made redundant making an extension of the switch.
5.10 onwards, if we are assuming the ARP part is done and the source host (aaaa.aaaa.aaaa) knows the MAC address of the destination (bbbb.bbbb.bbbb), then why the blue switch is flooding the frame? it should go directly to the destination... please explain..
I think the scenario here is that source host knows the destination host MAC maybe due to previous ARP but the destination hosts MAC is not present in the switch so switch has to flood
If I unplug hosts A and C form blue switch port 2, and then reconnect them but on different ports, what will prevent the switch from incorrectly sending it to the wrong port due to a now inaccurate MAC address table?
Thank you for this great content. So how would this work in a LAN where instead of a switch between the computers, you have those modern home routers that also act as wireless access point and a switch (has Ethernet ports)? If two computers in the same network are wirelessly connected to this device, how would they communicate? And will it be the same if it’s multiple devices in between them? like how you showed having a chain of switches in between the computers doesn’t change much.
You're welcome, Dez. The home routers act as both Routers and Switches. As Switches they sit in between all the Wifi devices and direct traffic between devices that are speaking to each other. The only difference is because of the WiFi joining process, they never need to flood, they always know the devices that are connected. With multiple Wireless Access Points (AP's) it's a little closer to the multiple switches depiction. Except that the AP's themselves are connected to each other physically.
@@PracticalNetworking Thank you for explaining that to me! Do you think you'll ever make a video about IANA, Autonomous Systems, the internet’s infrastructure, and how it's related to what we've learned so far? I’ve been trying to connect all the dots but I’m struggling with it.
@@DesertHash Hey, sorry, just saw this. TH-cam's comment system isn't good for responding to responses =/ At some point, yes, probably. It might be a later lesson in the full Networking Fundamentals course, possibly around when I'll be talking about Routing Protocols on the Internet. In the mean time, a lot of what you are asking about is discussed in the CCNA exam, you might find answers to what you are looking for in some of my CCNA related content: www.practicalnetworking.net/index/ccna/ Hope it helps.
Quick query. Once C has sent- received with B when it sends packet for D, will the second router still do a unicast flooding or forward to only port 5 knowing that port 6 is already mapped to B (and therefore not D)?
Hi Partha. Great question. The second switch *will* do a unicast flood. Just like Port 4 was connected to another switch, Port 6 might also be connected to a third switch, and maybe Host D is connected to *that* switch. Therefore, since the second switch doesn't know where the all D's MAC address is, it will always flood. Hope this helps. Glad you've enjoyed this series. It's been fun reading your comments and progression on the videos so far!
@@PracticalNetworking got it. Thanks for clarifying that. One more, how does it resolve localhost? I mean, what's the packet flow for curl localhost:80
@@parthamishra09 That's a product of DNS... sort of. But it's uninvolved in the process of switching. Localhost always resolves to 127.0.0.1. Which is a special IP address pointing to "itself". So when you curl or ping localhost/127.0.0.1, you are actually pinging/connecting to your own computer. Normally when pinging a name (like PracNet.net) your computer uses DNS to turn "PracNet.net" into an IP address, which it can then use as the destination IP address for packets. In the case of LocalHost, that one is special, so the computer doesn't actually need DNS to resolve it to 127.0.0.1.
@@PracticalNetworking Agreed/ Understood. Now, when the destination IP is 127.0.0.1, how would the packet be sent if you could help me understand that.
Normally it doesn't, and therefore has to use ARP. But for this illustration I skipped ARP on the hosts intentionally in order to focus on teaching Switching.
Question: When the switch does the broadcast or unicast it seems to send the actual data along with L2 layer to other hosts who are not intended to receive the data .. I feel like sending the actual payload to other hosts is unnecessary.. please correct me if i have wrongly understood .. thanks!!
It _does_ include the actual payload in the floods. This is what actually gets the data to the intended host. And is also why you shouldn't assume privacy from other hosts on the same IP network as you. (this in fact is why you separate hosts with similar connectivity requirements on to different "networks" - remember the classroom example back in Lesson 1). Consider, if the payload was *not* sent, there would have to be an acknowledgement system by the receiving host to receive the "empty" L2 header from the switch and then respond by saying "Yes, this is me" to populate the MAC table, such that the header _with_ the payload can then be sent. But that is a lot of additional complexity... remember every host is chatty, so switch mac address tables almost instantly get populated as soon as a host is connected. In fact, often hosts send a "Gratuitous ARP" when joining a new network just to announce their existence, which also serves to populate all the MAC address tables. Details here: www.practicalnetworking.net/series/arp/gratuitous-arp/
The Switch doesn't know IP addresses. The ARP question is looking for a MAC addresses associated with a particular IP address. So the switch can not know which port a particular IP belongs to.
Hi @Practical Networking, I just want to ask, in 7:30 why green switch did not flooding or perfom unicast to host D. I think it supposed to be done, since MAC Address table for port 5 is not populated yet. Am i right ?
Because no frames were sent with a destination MAC address of DDDD. The frame was sent to AAAA, and at that point in time, the Green switch knew where AAAA existed (and didn't need to flood).
In case if I send a command to shut down a computer will the Switch be able to detect that the port is still connected even with the computer turned off and then the MAC will only be removed after the MAC lifetime expires? If the network cable is disconnected it will remove immediately because the Switch detected that the port is no longer connected is that it? Is there then such a difference?
If the computer is off, it's not powering it's side of the NIC, which means no signal is going to the Switch, which means it's identical to the computer being not plugged in. The Switch detects something is disconnected because the electrical signal on the port stops. That will happen if you unplug something, or turn off the computer.
@@PracticalNetworking I am going to make sure i check you before anyone else when it comes to networking etc. Thankyou for all your hard work my friend.
🚨📢 Update: *Full Course is Under Construction* --> pracnet.net/networking
👉👉 Enroll now for *discounted early access* to the course and a chance to help shape its content.
📺▶ Module 1 Playlist - Networking Fundamentals: th-cam.com/play/PLIFyRwBY_4bRLmKfP1KnZA6rZbRHtxmXi.html
💭💬 Join us on Discord: pracnet.net/discord
_--- Original Comment below: ---_
*Full Course Status: Wait and See.*
Hopefully you've come to realize that I put _a lot_ of effort into the content I create. I'm not a course creator that will simply turn on the screen recording and ramble, then call that teaching. I meticulously plan _every_ module and lesson to _maximize the learning and value_ for the student.
To that end, it takes me a while to put together courses. If I'm going to dedicate the time, resources, and energy to putting this full course together, I need to know that there is enough interest in the full course. I'm rating that by how wide a reach this series achieves.
*If you are interested in seeing the full course developed, then the best way to bring that to fruition is to spread the word about this content* . By itself it already conveys _a lot_ of value. So sharing even just the 7 lessons (13 videos) in this series will surely help whoever you share it with.
Plus ... many online communities would greatly benefit from these videos. Think of all the Internet points you could acquire if you shared this series (karma, likes, follows, etc.) 😉
Use this link to share the full series:
th-cam.com/play/PLIFyRwBY_4bRLmKfP1KnZA6rZbRHtxmXi.html
Also, if you share it on Twitter or LinkedIn, please tag me =):
twitter.com/ed_pracnet/
www.linkedin.com/in/eharmoush/
definitely !!
@@parthamishra09 Thank you =)
Where's the router part of the playlist?
@@ultimatewarriorfrieza275 Just published Part 1 of the Router video a few days ago:
th-cam.com/video/AzXys5kxpAM/w-d-xo.html
Part 2 releases next week =)
Well, you probably don't understand it, but you helped quite a lot of people, and the thing you have done is something most people ask to be paid for, and their quality cannot compare with this. I am slowly watching every single one of your videos, and I just felt a need to say thank you for all these nice lessons. All the best to you sir!
Hey Danilo! Thanks for the kind note. I'm so happy you're getting a lot out of this series and you recognize the effort I put into making these as high quality as I could. Feel free to say hello on Discord! pracnet.net/discord =)
Albert Einstein once said:
“If you can't explain it to a six-year-old, you don't understand it yourself.”
And you are my dear teacher can take 2 years old and teach him everything you want no matter how complicated that subject is.
That is an amazing gift you have.
Bravo!!! Thank you so much Professor.
This means a lot to me, actually. That quote from Albert Einstein is the same quote I have on my mission statement: www.practicalnetworking.net/about/
Thank you for the note. Truly.
@@PracticalNetworking Choosing precisely this quote shows us all how wonderful a guy you are. Thank you very very much!!!
I have to say that I literally searched plenty of courses on TH-cam about networking fundamental , never come across a one that explains it this clearly, sorry for my bad english, thank you so much from the bottom of my heart 🙏
Glad this content is helping, Hicham =)
I learned more from this channel in a few days than I ever did in university in 4 years. You're amazing. Because of you, I have a better understanding of networking fundamentals. Thank you very much and keep up the good work. ❤
We didn’t have a networking class in college and this video explains networking so simply and intuitively. Thank you for demystifying computer networking.
Hi Kagame, thank you so much for the kind words and the donation. I'm honored to have helped with your networking journey and I'm sorry that a class like this wasn't available to you through your college!
Your donation helps support the channel and the creation of more content. Thank you very much for your support =).
Omg 😮 you're simple and easy to listen too! Are you a teacher? If you're not you should be and they should pay you large! You're wonderful thank you for all of this at the end I'll donate and share!!! 10/5 stars you're brilliant!!!!!
Thanks for the kind words =) I was a professional trainer at one point. Never formally an academic teacher (although, I was a adjunct professor for one semester at a tech school)
Either way thanks for your support and thank you for your shares =)
Thank you very much! So much more interactive and intuitive than trying to learn this from a book :)
Oh fuck man, he is really good at this!
Hi Jonathan, thank you for your Super Thanks donation! Your generosity is greatly appreciated =)
Donations like this directly aid in the development of more free, top-notch training content for all viewers. =) I'm humbled at your willingness to support the the channel.
Thank you again. Cheers !
Really appreacited what this man did!! From the introduction to in depth lessons!! Omg this is brillant. You need to replace all the professors here in melbourne lol
Would love to =)
Now that you've explained Networking Fundamentals in such a way... Could you tackle other things like Stock Market Calls and Puts?!
Only partially kidding. Best internet instructor I've ever seen.
This is the ultimate fundamental course …. Lovely support and respect
Thank you, Mohammad!
Wonderful content, as always. Very clear, plenty of detail. A must for those learning from the ground up how networking works!
Thank you, Ataru. Thank you for your support.
These are by far the best computer networking videos on TH-cam. Thank you for all your work @PracticalNetworking!
You're very welcome. Glad you enjoyed it!
I am watching this again, like new wine, its evergreen. Thank you.
Excellent Content. I am glad that I came across the channel sooner or later. The WireShark captures on the website for concepts such as ARP, GARP on the website in addition to videos are icing on the cake. Please keep the videos coming, only a matter of time that you get more views and subscribers if you keep up the same level of quality in the future videos. Thanks for everything.
Thank you for the kind words. Glad you found these videos and the ARP/GARP articles on my blog helpful =).
Hoping to get back at it with this series some time in the next four weeks. =)
as always in this series you explained everything so well and in detail. Thank you for all of these videos.
Keep up the good work👍
Thank you, Jamal. I appreciate the kind words =)
Thank you for the superb quality of the information you've made available and for the effort involved in putting it together. I also really appreciate that this information is generic rather than product specific so we get to learn how the fundamentals work rather than having to filter out marketing hype.
Yes! Keeping it vendor agnostic was a goal for this series. This way the knowledge applies all devices/software.
Glad you enjoyed it =)
Just finished the series, man these videos were so helpful! It's a shame that there is no more, but I appreciate all you have taught me in such a simple way. I Liked all the vids, and I will share with my friends. Thank you. :)
Thank you, Raymond. I appreciate your support and shares =).
Join us for the live stream today, I'm teaching through the newest content (Routers!)
I just discovered your top notch videos. They're very easy to follow and understand, actually I find them very exciting. I'm binging on them. Thank you. I consider your style and content to be the best out of all on TH-cam.
THank you for the kind words, Sarinaht. Glad you are enjoying this series!
Could you do me a favor? Do you mind sharing this video on Linked In, Reddit, Twitter, Facebook, or any other social media you use? As an independent creator, that would be an _enormous_ help, and I would appreciate it _greatly_ .
Thank you so much for these very clear and concise instructional videos! You are a truly a gifted teacher!
Around 9:03 mark I think the 2nd MAC Address Table's last 2 entries will be swapped if I understood your explanations correctly i.e. entries would be in the order?
4 aaaa.aaaa.aaaa
6 bbbb.bbbb.bbbb
4 cccc.cccc.cccc
5 dddd.dddd.dddd
You're correct. The 4cccc.cccc.cccc and 5 dddd.dddd.dddd on the right side have to be swapped.
This network fundamentals simply awesome.
Glad you're enjoying it, Surender =). Thank you again for helping bring attention to this content.
Good job as usual. You deserve way more viewers and subscribers. Keep it up!
Thanks Antonio. I appreciate the kind words. =)
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_--- Original Comment below: ---_
*Full Course Status: Wait and See.*
Hopefully you've come to realize that I put _a lot_ of effort into the content I create. I'm not a course creator that will simply turn on the screen recording and ramble, then call that teaching. I meticulously plan _every_ module and lesson to _maximize the learning and value_ for the student.
To that end, it takes me a while to put together courses. If I'm going to dedicate the time, resources, and energy to putting this full course together, I need to know that there is enough interest in the full course. I'm rating that by how wide a reach this series achieves.
*If you are interested in seeing the full course developed, then the best way to bring that to fruition is to spread the word about this content* . By itself it already conveys _a lot_ of value. So sharing even just the 7 lessons (13 videos) in this series will surely help whoever you share it with.
Plus ... many online communities would greatly benefit from these videos. Think of all the Internet points you could acquire if you shared this series (karma, likes, follows, etc.) 😉
Use this link to share the full series:
th-cam.com/play/PLIFyRwBY_4bRLmKfP1KnZA6rZbRHtxmXi.html
Also, if you share it on Twitter or LinkedIn, please tag me =):
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Man, it can't any clearer than this!! Thanks
Cheers, Mohammed. Glad you enjoyed it =)
amazing explanation , thank u for making this serie.
Great content, your explanation so far is the easiest for me to understand AND remember afterwards. Thanks a lot!
That's almost exactly my mission statement =). Knowledge that is easy to learn and easy to pass on. Glad you enjoyed it, Alice.
www.practicalnetworking.net/about/
Very good video.
Thanks again for your work !
That's gonna be probably the only TH-cam tutorial series I will ever finish :) Incredible content and clear presentaton. I am currently doing Google's cybersecurity certificate and their module on networking can't even compare to yours. The plan is first finish to this series and then go back to the certificate.
A lot of folks are here from Google's cert. Glad you're finding help and knowledge with this series. Good luck with completing it!
Thanks so much, I know I'm going to pass my Network+ exam because of you - your videos and explanations are so clear and easy to understand.
Hi Vicki-Ann! Thank you for supporting the channel. Contributions like this help support the continued development of free content for everyone else. =)
If anyone else reads this comment, you should thank Vicki-Ann for funding the free resources you are enjoying. =)
Thanks again, Vicki-Ann !
Update, I passed!
@@vicki-annthornton8330 WOhooo! Congratulations! Net+ is no small undertaking =)
@@vicki-annthornton8330
Wow, congratulations!
Very well done with crisp clear example! You definitely know your stuff, thank you for sharing the knowledge.
It was very clear!
Thank you for the video!
This is amazing!!
You are a great teacher. Thanks for your explanations so simple to understand
If I were a teacher in high school or college I would use your videos to explain the infrastructure of the world we live.
Really enjoying the course so far. Great job and thank you!
Thanks Bro, really appreciated your work. I am truly amazed with the quality of your work.....thank you thank you
Thanks for the kind words and all your comments. I enjoyed seeing them on all the video series you watched. So glad you enjoyed them. Wish you luck w/ your studies =). Cheers !
Thanks for such a detailed video ❤❤
Thank you for this! I hope you continue to make these wonderful videos
Better than my professors in college.
Excellent video!
So in simple definition the difference between broadcast(ing) and flood(ing) is that: Broadcast is an intentional way of sending messages or packets to all the devices connected to the network, but flooding is a way of unintentionally or uncontrollably sending messages or data to all the connected devices in a network. In broadcasting the destination address is known while in flooding the destination is unknown. Real world example of these can be as follow:
Broadcast : For example you are in a room and you intentionally speak loudly to everyone in the room so they can hear and understand you.
Flooding: For example - you have a pipe and there is a leak in the pipe and the water spreads out of the hole and spreads unintentionally and uncontrollably across the room, and make the room wet. The same thing happen to network.
I hope I made it clear and understandable......... give me a like for understanding this real world example of "Broadcast & Flood"
I'd say flooding is more of the same speaking loudly in a room, but you not addressing everyone, but the unknown person in the crowd.
Always helpful....Thank you ❤️
You're welcome!
thank you so much sir, no one could understand networking like you...please we need full course...we stand in front of you
Great video
Thanks again.
Thank you very much
If the computer is disconnected from the port or does not communicate for a long time, or in case of changing the network card, the MAC address table entry is erased due to aging time? Does the Switch remove the MAC input because it has detected that the port is no longer connected or is the MAC input removed because the lifetime has expired (aging time counter)?
Both. If a switch detects the cable is disconnected typically it will purge the mac addresses associated with that port. Also, typically MAC address also age out if there is no activity from the host (5min is common, but probably each vendor has different values).
@@PracticalNetworking In case if I send a command to shut down a computer will the Switch be able to detect that the port is still connected even with the computer turned off and then the MAC will only be removed after the MAC lifetime expires? If the network cable is disconnected it will remove immediately because the Switch detected that the port is no longer connected is that it? Is there then such a difference?
Hello sir.
great course.
I have a question, why on the mac address in the green one, the cccc is the last one? it not should be one before? because the 4 port get the cccc, and only after its get the dddd back.
Please if you can explain,
Thank you
Thanks for the amazing video
Thank you
This is the kind of videos I was looking for to learn networking! Thanks a lot for this!
I had a follow up question:
1. What happens to the MAC address mapping table when I disconnect a host from a switch and replace it with another host which has a different MAC address? How does the MAC Address Table (and ARP Cache) get refreshed ? Is there a retry on fail, or are the MAC Address Table (and ARP Cache) proactively refreshed on detection of a new hardware connected to the network ?
Also, is there a networking fundamentals course (paid) that you have? I would love to learn more about networking fundamentals from you.
Great job
What happens when the MAC Address Table for Host D has been mapped out and the physical connection of Host D is moved from the green switch to the blue switch? Will the next packets from Host A to Host D be undelivered?
Great question! It shows you are really thinking about this stuff.
Typically, when a device is disconnect, the switch will detect that a port is no longer connected and "forget" any MAC addresses learned on that port. So if Host D was removed, it's MAC entry would be purged from the green switch, and the next communication with a destination MAC of Host D would be flooded.
But in your example, the Blue switch had no physical connection removed, so will continue to think that Host D exists out port 3... and will continue to forward packets that direction to (try to) reach Host D.
This would occur until Host D sent _anything_ in which case the Blue switch will see traffic with a source MAC address of DDDD arrive on a different port, and will therefore update it's MAC address table.
With nearly any computer these days, as soon as you are plugged in, software is attempting to speak on the network so this actually happens pretty much instantly (consider software/app updates, weather apps, location apps, email apps, etc... all of them are constantly speaking in the background).
Thanks Bro, really appreciated your work.
Thanks!
thank you, let's boost the algorithm!
6:27--> "the blue switch just did unicast flooding". I think the correct term is broadcast flooding since the switch send the frame wherever possible (I understand that switches don't cast, but I only try to convey the meaning...)
Hi Sir. Thank you for all your videos. I'm rewatching everything and I have a question. What happens to the MAC address table after you unplug the host from the switch? Will the switch automatically delete the entry related to that port in the MAC address table?
was going to edit my previous comment after I learned a bit more about MAC address table but it disappeared for some reason. The answer to your question is yes, when a host is disconnected from a switch, the entry related to that port in the MAC address table gets deleted.
@Hello World answered it correctly =). If you have more questions, feel free to ask in Discord: pracnet.net/discord
Great video and really in depth explanation,
i having difficulties to understand the Unicast frame and the Broadcast Frame, I grasped their terminology, but what i am struggling to understand is that, wont a Unicraft frame always use ARP protocol to determine where the traffic its going and so it can be added to the MAC address Table?? Thank you
Ed you're 00000010 good!
=)
great video!
THANK YOU SIR, Iget to know there is no sound attached to the video.
9.35 : when port 3 has bbbb mac address, and when host c wants to sent to host d obviously port 3 has B's address so to find out host D 's address switch going to flood frames to all hosts ?
At the timestamp you linked, both switches knew where all hosts existed, so there would be no flooding. Only forwarding out the necessary switchports.
You are the best.
LOVE YOU SIR
Nice video!!! I have one question. In the last video, you mentioned you said we need IP address of a switch when we are communicating something TO the switch but do not need IP address when we are communicating through the switch. What is the difference. I don’t understand in which cases we will be communicating to the switch.
I am sorry if it sounds like a stupid question. I am actually unable to understand.
This is great!
=)
Hi @Practical Networking
Shouldn't the second Switch have this MAT:
4. aaa
6. bbb
4. ccc
5. ddd
Since it receives a new frame from an unknown MAC address, shouldn't it map CCC first before DDD?
Regardless, I very well understood the concept on this video. Thank you!
great video!! but I want to ask you does the order in the MAC address matters? because what I got in order for green switch MAC address table was 4. aaaa, 6. bbbb, then 4. cccc (host C sent data intended to host d), finally 5. dddd. sorry if it's confusing I just want to make sure my understanding about this one. thanks!
Nope, order is irrelevant! Glad you enjoyed the video!
Does a switch only flood ports that it does not have a MAC address assigned to? I guess probably not for the cases where a port might contain multiple MAC addresses?
Thanks
is multicast another term for broadcast?
No, they are different.
Broadcast - send this frame to *everyone* on this network
Multicast - send this frame to *everyone in a specific multicast group* on this network
Unicast - send this frame to *one other person* on this network
I know you didn't ask for Unicast, but the definition helps clarify how Multicast is "in between" Broadcast and Unicast.
HTH
Is it possible that a switch, instead of storing multiple mac addresses for one port(indicating that that port is likely connected to another switch), that an implementation might overwrite? Just wondering if that's a valid implementation. I'm speculating about this next part but if this is done then the next time another device tries to send to the MAC that was overwritten that it would just unicast flood again.
It's possible, but that wouldn't scale. There are hierarchies of switches that might have 1000s of hosts on a single port. If each is overwriting the last, it would cause 999 hosts to be unicasting flooding at any given time.
@@PracticalNetworking Lol, that's kinda funny to think about. I only ask if it's something i would need to watch out for. Thanks.
Hi, when u say switch can flood and learn , then why at all ,there is a need of sending ARP request. ? just send the frame from host A , switch will learn the from next time.
Why doesn't ARP update the mac address table? It seems like the flood is redundant after the first broadcast from ARP
Could I ask something, do we need IP address for communicating within the same network, why or why not?
I have a question. When the green switch forwards the frame to the blue switch, why doesn’t it change the source max to its own mac, instead of keeping the source mac as the mac of device A? Lovely videos btw ❤️
Switches were intended to be transparent -- almost like an extension to the wire itself. So they make no modifications of the packet/frames that are sent through them.
Glad you enjoyed it =)
Take a look at the explanation about "data THROUGH the switch" and "data TO the switch" in the previous video of this series.
I have a small question. From 5:14 the network that both switches using is the same right? Since switch communicates within network and router are for foreign network. Hope my question is clear enough to understand.
7:01 why doesn't the switch doesn't perform ARP at this point, to save itself having to broadcast the unicast frame ? isn't it safer aswell since you are not sending private information to hosts ??
To do arp you are going to require ip address and switch is layer 2 device .
@9:33, I got the solution as:
1 aaaa 4 aaaa
3 bbbb 6 bbbb
2 cccc 4 cccc
3 dddd 5 dddd
Is this incorrect? I could see that in your solution the order between 4cccc and 5dddd in mac address table 2 is the reverse of mine. Kindly suggest.
The order is irrelevant. As long as you got the right entries in the right ports =)
@@PracticalNetworking thank you so much for the explanation.
I dont understand why we still use a unicast frame even without knowing the destination MAC.
What the host sends is independent of what the switch knows.
If the host knows the MAC, it can sent a Unicast frame. If the host doesn't know the MAC, it _must_ send an ARP request.
But remember the Switch is completely independent. Consider if the switching path changes _after_ the host already learned the MAC address. Then the new switch might not know the destination MAC and might resort to Unicast flooding.
hope this helps =) Glad you've enjoyed this series!
What happens when the network configuration changes? I.e. a device is removed, replaced by another one, etc.
A switch detects the interface going down and purges the MAC address table entries associated with that port.
This differs declaring the port as a switch or using the port suggested for it? I think not. Or in many Cisco switches are a yellow one or 2 or 4 for it. With special cables. In the 9300 cascading is made redundant making an extension of the switch.
Not sure I'm following your question =/
Is there a difference on choosing the port for link between switches?
Thanks Sir
You're welcome =)
5.10 onwards, if we are assuming the ARP part is done and the source host (aaaa.aaaa.aaaa) knows the MAC address of the destination (bbbb.bbbb.bbbb), then why the blue switch is flooding the frame? it should go directly to the destination... please explain..
I think the scenario here is that source host knows the destination host MAC maybe due to previous ARP but the destination hosts MAC is not present in the switch so switch has to flood
If I unplug hosts A and C form blue switch port 2, and then reconnect them but on different ports, what will prevent the switch from incorrectly sending it to the wrong port due to a now inaccurate MAC address table?
Great Q. When a switch port is disconnected, switches clear all Mac addresses associated with that port.
Thank you for this great content.
So how would this work in a LAN where instead of a switch between the computers, you have those modern home routers that also act as wireless access point and a switch (has Ethernet ports)?
If two computers in the same network are wirelessly connected to this device, how would they communicate? And will it be the same if it’s multiple devices in between them? like how you showed having a chain of switches in between the computers doesn’t change much.
You're welcome, Dez.
The home routers act as both Routers and Switches. As Switches they sit in between all the Wifi devices and direct traffic between devices that are speaking to each other. The only difference is because of the WiFi joining process, they never need to flood, they always know the devices that are connected.
With multiple Wireless Access Points (AP's) it's a little closer to the multiple switches depiction. Except that the AP's themselves are connected to each other physically.
@@PracticalNetworking Thank you for explaining that to me!
Do you think you'll ever make a video about IANA, Autonomous Systems, the internet’s infrastructure, and how it's related to what we've learned so far?
I’ve been trying to connect all the dots but I’m struggling with it.
@@DesertHash Hey, sorry, just saw this. TH-cam's comment system isn't good for responding to responses =/
At some point, yes, probably. It might be a later lesson in the full Networking Fundamentals course, possibly around when I'll be talking about Routing Protocols on the Internet.
In the mean time, a lot of what you are asking about is discussed in the CCNA exam, you might find answers to what you are looking for in some of my CCNA related content: www.practicalnetworking.net/index/ccna/
Hope it helps.
Quick query. Once C has sent- received with B when it sends packet for D, will the second router still do a unicast flooding or forward to only port 5 knowing that port 6 is already mapped to B (and therefore not D)?
Hi Partha. Great question. The second switch *will* do a unicast flood. Just like Port 4 was connected to another switch, Port 6 might also be connected to a third switch, and maybe Host D is connected to *that* switch. Therefore, since the second switch doesn't know where the all D's MAC address is, it will always flood.
Hope this helps. Glad you've enjoyed this series. It's been fun reading your comments and progression on the videos so far!
@@PracticalNetworking got it. Thanks for clarifying that. One more, how does it resolve localhost? I mean, what's the packet flow for curl localhost:80
@@parthamishra09 That's a product of DNS... sort of. But it's uninvolved in the process of switching.
Localhost always resolves to 127.0.0.1. Which is a special IP address pointing to "itself". So when you curl or ping localhost/127.0.0.1, you are actually pinging/connecting to your own computer.
Normally when pinging a name (like PracNet.net) your computer uses DNS to turn "PracNet.net" into an IP address, which it can then use as the destination IP address for packets. In the case of LocalHost, that one is special, so the computer doesn't actually need DNS to resolve it to 127.0.0.1.
@@PracticalNetworking Agreed/ Understood. Now, when the destination IP is 127.0.0.1, how would the packet be sent if you could help me understand that.
How will the 1st host know the Mac address of the other host communicating in beginning when using switching. In 1:00
Normally it doesn't, and therefore has to use ARP. But for this illustration I skipped ARP on the hosts intentionally in order to focus on teaching Switching.
Question: When the switch does the broadcast or unicast it seems to send the actual data along with L2 layer to other hosts who are not intended to receive the data .. I feel like sending the actual payload to other hosts is unnecessary.. please correct me if i have wrongly understood .. thanks!!
It _does_ include the actual payload in the floods. This is what actually gets the data to the intended host. And is also why you shouldn't assume privacy from other hosts on the same IP network as you. (this in fact is why you separate hosts with similar connectivity requirements on to different "networks" - remember the classroom example back in Lesson 1).
Consider, if the payload was *not* sent, there would have to be an acknowledgement system by the receiving host to receive the "empty" L2 header from the switch and then respond by saying "Yes, this is me" to populate the MAC table, such that the header _with_ the payload can then be sent.
But that is a lot of additional complexity... remember every host is chatty, so switch mac address tables almost instantly get populated as soon as a host is connected. In fact, often hosts send a "Gratuitous ARP" when joining a new network just to announce their existence, which also serves to populate all the MAC address tables. Details here:
www.practicalnetworking.net/series/arp/gratuitous-arp/
@@PracticalNetworking Thank you so much .. this helps .. 🙏
@@antonyrichard369 Glad to hear, Antony =). Hope you get a chance to check out the rest of the series, I feel you will get a lot out of it. Cheers!
Does the port of the two switches i.e. port 3&4 will every time modify when new host communicate to the other host? In 8:18
Yes. Every time communication flows across that switch link, a mac table entry will be added/updated.
if we do consider arp , doesnt that mean switch will know what the mac add of destination pc is?
The Switch doesn't know IP addresses. The ARP question is looking for a MAC addresses associated with a particular IP address. So the switch can not know which port a particular IP belongs to.
@@PracticalNetworking oh yes duh, but for arp reply , switch will update its mac table right ?
Hi @Practical Networking,
I just want to ask, in 7:30 why green switch did not flooding or perfom unicast to host D. I think it supposed to be done, since MAC Address table for port 5 is not populated yet.
Am i right ?
Because no frames were sent with a destination MAC address of DDDD. The frame was sent to AAAA, and at that point in time, the Green switch knew where AAAA existed (and didn't need to flood).
@@PracticalNetworking Thanks.. Sorry, just find out after I finished your video.
In case if I send a command to shut down a computer will the Switch be able to detect that the port is still connected even with the computer turned off and then the MAC will only be removed after the MAC lifetime expires? If the network cable is disconnected it will remove immediately because the Switch detected that the port is no longer connected is that it? Is there then such a difference?
If the computer is off, it's not powering it's side of the NIC, which means no signal is going to the Switch, which means it's identical to the computer being not plugged in.
The Switch detects something is disconnected because the electrical signal on the port stops. That will happen if you unplug something, or turn off the computer.
👍👍🙏🙏
Blimey that was somewhat hard
Take your time. Step through it slowly. Ask questions if you have any =)
@@PracticalNetworking I am going to make sure i check you before anyone else when it comes to networking etc. Thankyou for all your hard work my friend.
@@AliTwaij You're welcome, Ali. Cheers =)
Dude go with fastest speed on fundamental this course i want to learn basic so that i can go for advance
why did it take too long for me to find this
Wish I knew the answer to that question =). But glad you found it now!
Its 2 ccc 4 ccc and 3 ddd and 5 ddd.
Host C -> Host D..... HOST DEEZ NUTS
Press FFFF to pay respects
Is that a broadcast joke =) ?