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2 points · 1 day ago

255.255.255.255 -- this is an IPv4 L3 broadcast, a packet sent to this address will be delivered to every member of the local network

FF02::1 -- this is an IPv6 L3 "All Nodes" multicast, a packet sent to this address will be delivered to every member of the local network.

The effect is the same.

IPv6 doesn't have a dedicated "broadcast address", instead IPv6 uses a dedicated multicast address to have the same effect as an IPv4 broadcast.

1 point · 1 day ago
3 points · 1 day ago

Why? Because the standard said so.

No seriously. That is it.

You'll get why's along the lines of "because the Network ID is used to as the identifier of the network, and hence can not be assigned to a host that is a member of the network. But in IPv6, the concept of the "Network ID" doesn't exist -- the first IP address is 100% usable as a host address as well.

It would have been absolutely possible for the first address in an IPv4 address to also be usable as a Host address, but the standard chose not to for the sake of seperating the "combination of bits" which identify the network vs the 'combination of bits" which identify a host on the network.

IPv6 does not make the same restriction, proving the technical feasibility.

167

The complete Subnetting Mastery Video series has released! This series is intended to be the last Subnetting videos you will ever need to watch (and the feedback seems to confirm the goal is achieved).

Watching this series will take you from knowing little or nothing about Subnetting, to being a Subnetting pro. The series also includes a practice problem generator to practice your new found skills (see the end of Video 4 for details).

The series is offered 100% free. The Youtube channel is not monetized. I make no revenue from you watching. I am offering it because Subnetting is something junior Network Engineers have struggled with for too long, and its time for us (as in industry) to move past it.

Subnetting Mastery

Part 1: What is Subnetting?

Part 2: Drawing the Subnetting Cheat Sheet

Part 3: Using the Cheat Sheet

Part 4: Practice Examples

Part 5: Time-Saving Tricks

Part 6: Subnetting in the /17-/24 range

Part 7: Subnetting in the /1-/16 range

If you're already comfortable with Subnetting and just want a sample of what the videos are like, I would recommend Video 5, 6, or 7 to see the quality of the series and the subnetting process in action.

If you know of someone that could benefit from learnining to Subnet, please share with them this short link: pracnet.net/sm -- it will automatically redirect them to the full series on Youtube.

I've worked really hard on this series, put a lot of hours into them, and am very proud of the results of course, I am still open to feedback. I truly hope you enjoy the videos and learn once and for all how to subnet.

167
31 comments

Hey mate I am from your youtube channel the guy who requested VLSM if you remember, and yes these videos along with my own understanding of subnetting helped me a lot. awesome work there looking forward to more router/ and switch practicals plz lol

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Original Poster2 points · 13 days ago

Glad it helped =) Thanks for the comment on YT =)

And VLSM has been added to my "list of projects" for the future. Maybe I'll do an informal session for the /r/ccna community.

hey mate

thx for the reply, what do you do actually are you a IT tutor?, I am in the process of doing CCENT to CCNA just wondering if you got anything to help me out with it?
cheers

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Original Poster1 point · 3 days ago

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4 points · 5 days ago

There are two parts to configuring an access port: 1. Telling the port it is an access port, and 2. Telling the port what VLAN it is a member of.

These commands fulfill the two steps above:

switchport mode access
switchport access vlan 33
  • If you don't configure the 1st command, the Switchport's default switchport mode is dynamic auto, which will conditionally negotiate as either a Trunk or an Access port (as opposed to being explicitly set as one or the other). This is a function of Dynamic Trunking Protocol.

  • If you don't configure the 2nd command, the Switchport will by default be a member of VLAN 1.

To learn more about all the other commands required to configure VLANs on Cisco switches, read this. To learn more about all the show commands available to verify the VLAN operation of a switch, read this. Lastly, to read about all the default settings a switchport is in before you apply any commands, read this.

erh_ commented on
r/ccnaPosted by
4 points · 7 days ago

Yes. Each layer adds its own header, and everything else is simply considered "Data".

Check out this animation for an illustration:

https://www.practicalnetworking.net/wp-content/uploads/2016/01/packtrav-encap-decap.gif

^source

Great video (other than that the header doesn't actually become a footer).

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1 point · 7 days ago

Yea, I can see how it can appear as that. I wanted to keep the headers facing the OSI model in the animation, to keep the whole illustration vertically symmetrical.

I also didn't want to include the trailer for L2. The article this animation comes from is intentionally staying very high level. It is from a series that is meant to teach anyone how packets move through a network -- which means the audience isn't just network engineers or cisco candidates, etc.

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Question ...so I have vlan 10, ports 1 and 2

and vlan 20 ports 3 and 4

and vlan 30 ports 5 and 6 on switch 1

now I want to make a trunk port on port 8

This port is not in any of those vlans right?

Int fa 0/8

switchport trunk encapsulation dot1q

switchport mode trunk

switchport trunk native vlan 2

And I repeat this on the other side on the other switch.

So the trunk port is in a vlan on its own?

and if i have three switches connected then they all have to be native vlan 2?

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1 point · 8 days ago

After this on both Switches:

Int fa 0/8
switchport trunk encapsulation dot1q
switchport mode trunk

Traffic for VLANs 10, 20, and 30 will flow between the switch and a VLAN Tag will be added to traffic as it traverses the trunk (fa0/8).

Remember, the traffic traversing between these switches is just a bunch of 1s and 0s -- the VLAN tag identifies which 1s and 0s belong to VLAN 10, or VLAN 20, or VLAN 30, etc.

Then you configure this on both switches:

Int fa 0/8
switchport trunk native vlan 2

And the behavior above is identical -- no changes.

Then, if you configure this (on both switches):

Int fa 0/8
switchport trunk native vlan 30

Now Traffic for VLANs 10, 20, and 30 will still flow between the two switches. Except the traffic for VLAN 30 will not have a VLAN tag.

That is all the Native VLAN configuration does. It identifies a single VLAN whose traffic will traverse a trunk port without a VLAN tag.

Original Poster1 point · 11 days ago

Ok I’ll check it out. But does every frame at one point go through the native vlan?

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1 point · 10 days ago

The native VLAN isn't really its own path or VLAN. Its simply the VLAN that traverses a trunk that doesn't require a tag.

So no, every frame mustn't go through the native VLAN. It can, or it can't.

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I've been subnetting for years now, but I really appreciate your work! Keep it up!

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1 point · 8 days ago

So glad you enjoyed it! Thanks for the kind words!

8 points · 18 days ago · edited 17 days ago

I finally released the last video of a 7-part Subnetting Mastery video series. Each video is 2-8 minutes long and will comfortably take someone with little to no exposure of subnetting, to solving subnetting problems in any octet in 60 seconds or less.

Subnetting Mastery

Part 1: What is Subnetting?

Part 2: Drawing the Subnetting Cheat Sheet

Part 3: Using the Cheat Sheet

Part 4: Practice Examples

Part 5: Time-Saving Tricks

Part 6: Subnetting in the /17-/24 range

Part 7: Subnetting in the /1-/16 range

If you're already comfortable with Subnetting and just want a sample of what the videos are like, I would recommend Video 5, 6, or 7 to see the process in action.

The videos do not mention classes, nor do they do binary conversions. This is a modern, realistic subnetting mastery video series that translates to real life practical subnetting more so than it does a specific certification exam.

The video series also contains a link to a subnetting problem generator. The details are at the end of Video 4.

3 points · 10 days ago

I just released a Subnetting Video series!

I've been teaching networking for years, and the method I teach is the best method I have found (the feedback also confirms this).

If you watch this video series and can't subnet like a pro. please please please let me know and talk to me about your pain points. I want this series to be the ultimate / last video series you will ever have to watch about subnetting.

Edit: It uses a very similar (if not identical) method to the "Magic Number" method people are recommending in this thread.

Your subnetting videos are super helpful. I have my exam scheduled for 8/30 and I feel a bit more confident in my subnetting now thanks to your cheat sheet idea. Thanks!

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2 points · 8 days ago · edited 8 days ago

^_^ Glad to hear it! Good luck with the exam! I'm sure you'll do well!

Original Poster1 point · 12 days ago

To summarize ARP’s operation:

  • When a Client is speaking to a host in the same network, it will ARP for the IP address of the host
  • When a Client is speaking to a host in a different network, it will ARP for the IP address of the Default Gateway

Should this state the MAC Address, and not the IP?

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1 point · 12 days ago

I can see the point you're making.

I meant it in the sense of..

  • It will [Try to resolve the MAC address] for the IP address of the host...
  • It will [Try to resolve the MAC address] for the IP address of the default gateway
Original Poster2 points · 12 days ago

Ok I see that now! "For" is sort of ambiguous so I just read it incorrectly.

Sorry about that!

So far this is a fantastic resource, exactly what I was looking for!

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1 point · 11 days ago

No worries =) Thank you for the kind words. Glad you enjoyed the series!

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9
Comments are locked

The complete Subnetting Mastery Video series has released! This series is intended to be the last Subnetting videos you will ever need to watch (and the feedback seems to confirm the goal is achieved).

Watching this series will take you from knowing little or nothing about Subnetting, to being a Subnetting pro. The series also includes a practice problem generator to practice your new found skills (see the end of Video 4 for details).

The series is offered 100% free. The Youtube channel is not monetized. I make no revenue from you watching. I am offering it because Subnetting is something junior Network Engineers have struggled with for too long, and its time for us (as in industry) to move past it.

Subnetting Mastery

Part 1: What is Subnetting?

Part 2: Drawing the Subnetting Cheat Sheet

Part 3: Using the Cheat Sheet

Part 4: Practice Examples

Part 5: Time-Saving Tricks

Part 6: Subnetting in the /17-/24 range

Part 7: Subnetting in the /1-/16 range

If you're already comfortable with Subnetting and just want a sample of what the videos are like, I would recommend Video 5, 6, or 7 to see the quality of the series and the subnetting process in action.

If you know of someone that could benefit from learnining to Subnet, please share with them this short link: pracnet.net/sm -- it will automatically redirect them to the full series on Youtube.

I've worked really hard on this series, put a lot of hours into them, and am very proud of the results of course, I am still open to feedback. I truly hope you enjoy the videos and learn once and for all how to subnet.

167 points
9
22 comments

i clicked through them all at 2x speed using preview to see what the slides said.

part 3 seems like the only real conceptual nuts and bolts, and while I wasn't listening to the audio it should be leaning on binary counting when explaining octets instead of relying on procedural equations like "256 - number"

figure out a way to add some 11111111.11111111.11111111.11000000 notations and translations so the audience knows why they're subtracting from 256.

otherwise, once they get that just give them an online subnet calculator URL.

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Original Poster1 point · 12 days ago

I would argue that the audio is a big part of it. The most "visual" videos are probably #1 and #7, but still without the Audio you're missing a big part of the value of the videos.

it should be leaning on binary counting when explaining octets

Respectfully, I disagree with you there.

Too many instructors try to teach Subnetting starting with Binary. The problem is Binary has a steep learning curve, and the challenge of learning binary then gets carried over to learning Subnetting.

Moreover, not a single Network Engineer I know still uses binary to subnet after getting through the exams.

I wanted to focus on a practical way of doing Subnetting, the way I did it when I was an engineer and not just studying for a test. Once the method is understood, circling back and doing the binary becomes much, much easier.

2 points · 12 days ago

of course you don't actually use binary to implement cidr subnets, but it explains why subnet octets skip from 0 to 128, why the numbers are called octets, why 255 is the upper limit, and what is actually being masked in slash notation.

also if you're focusing on practical instead of academic as a motivation to skip binary notation you might as well just skip all the examples and give them a subnet calculator instead.

binary notation makes sense of the numbers calculators spit out.

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Original Poster1 point · 12 days ago

if you're focusing on practical instead of academic as a motivation to skip binary notation you might as well just skip all the examples and give them a subnet calculator instead.

By that reasoning, why teach anyone anything? Just give them a link to Google.

but it explains why subnet octets skip from 0 to 128, why the numbers are called octets, why 255 is the upper limit, and what is actually being masked in slash notation.

These are fair points. I have considered adding an appendix video to cover VLSM and also Binary. I'm mostly sure I want to do VLSM, but still weighing about Binary. You're thoughts are making me lean towards committing to it, however.

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6 points · 12 days ago

You're thinking of Filtering. It is one of the four things all switches do: Learn, Flood, Filter, Forward.

Switch Operations -- Animated

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337
r/ccnaPosted by1 month agoGilded1

Hello,

I had a student ask me for a link of every article on my blog that covers CCNA topics. I put together this list, and thought I would pass it on to /r/ccna as well.

This doesn't cover the entire CCNA curriculum, but I earnestly believe that what it does cover, it does so in the best way possible. I am, of course, open to hear any feedback to the contrary =)

Practical Networking .net -- CCNA Curriculum Articles

Disclaimer: I wrote these articles, and I earnestly believe they will help the readers of this subreddit. These are all 100% free. There is no ads on the site. I make no revenue from you reading them. There is no mandatory e-mail sign up or soft paywall.

Edit: Whoa, this blew up. Thank you for the kind words, everyone, I'm really happy you're getting a lot out of the articles. Truly. Also, thank you for the gold, kind stranger =) Was not expecting that at all!.

337
52 comments

Used Practicalnetworking.net for my ICND1 and I can highly recommend it. Fantastic site.

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Original Poster1 point · 13 days ago

Glad it helped, SgtPackets! Grats on the Cert!

Thank you for these articles! I have been reading through to reiterate learned material. It turns out i had a fuzzy recollection of the material, but after these articles I know have a solid understanding of the topics. Very well written and explained, thanks!

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Original Poster1 point · 14 days ago

Awesome! Glad you enjoyed the articles _^

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78

We all work with non-network engineers on a day to day basis (sys admins, account managers, etc...). What topics do you wish they understood about "networking"? What topics would make your job easier if they understood it?

78
213 comments

How the OSI model works....

Seriously, I have to explain to people (server admins, desktop support, etc) that if the MAC address doesn't appear in the MAC table, it doesn't MATTER what IP it has, or if the windows firewall is on or off.

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Original Poster1 point · 14 days ago

I wrote this article specifically to teach the OSI model and what each layer does, and how they contribute to the over all goal of "computer to computer communication". It might help your colleagues, it would at least spare you from having to explain it to them ;)

https://www.practicalnetworking.net/series/packet-traveling/osi-model/

I'd love to give it to them, but they don't care enough to learn. Why do that when networking will tell them which checkbox to check on their windows server to make it work?

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Original Poster1 point · 13 days ago

I hear you.... you can lead a horse to water, but you can't make them drink. C'est la vie.

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191

Hey all!

A while ago I offered a free subnetting class with intentions of editing, polishing, and releasing the class as a free video series. I've finally finished doing so and am formally announcing the release of the first five videos.

I have full confidence that you can go from knowing nothing or very little about Subnetting to becoming a Subnetting Master just by watching these five videos.

Part 1: What is Subnetting?

Part 2: Drawing the Subnetting Cheat Sheet

Part 3: Using the Subnetting Cheat Sheet

Part 4: Practice Examples

Part 5: Time Saving Tricks

.

The final two videos are still in development, but they will cover the following topics:

Part 6: Subnetting in the /17-/24 range
Part 7: Subnetting in the /1-/16 range

The full playlist is available at this handy short link:

pracnet.net/sm

All the videos will also be listed on the subneting practice page I mentioned a months ago


I was initially going to release the videos one per week... but then I thought, some people are testing before five weeks from now, and I want them to have all the information at once. Hence, I've released to everyone, for free, every video I have created in the series.

If there is enough interest, I might do one or two informal live sessions to teach the content of Part 6 and 7 so that folks testing before those videos release can get the information they need.

Either way, I've put a tun of effort into these videos, and I really hope they help you truly wrap your mind around Subnetting. Feedback is welcome.

191
56 comments
5 points · 15 days ago

Cisco has a proprietary protocol known as Dynamic Trunking Protocol. The purpose of DTP is to auto-magically determine whether a particular switch port should become a Trunk port or an Access port.

Each (Cisco) switch can be configured to operate in one of 4 modes:

  • switchport mode dynamic desirable – actively attempt to negotiate trunk
  • switchport mode dynamic auto – passively attempt to negotiate trunk (default)
  • switchport mode trunk – statically set as trunk
  • switchport mode access – statically set as access

The four options above correlate to a Switch's Administrative mode -- aka, what an Admin (or the default configuration) has configured on the Switchport.

Then, based upon the combination of the mode on the local interface and the mode on the remote switch, each switch's interface will operate as a Trunk or Access port. This is referred to as the port's Operational Mode.

Both the Administrative and Operational mode are visible in the command show interface switchport:

SwitchX# show interfaces Ethernet 0/1 switchport
Switchport: Enabled
Administrative Mode: static access
Operational Mode: static access

A table of every combination of Administrative modes and their resulting Operational modes is available here:

https://www.practicalnetworking.net/stand-alone/configuring-vlans/#dtp

3 points · 15 days ago · edited 15 days ago

To the OP, it isn't a class, but its free. I don't recommend anyone to start a CCNA journey without at least understanding the basic process for how packets move through a network. To that end, here is a free article series that concludes with a video that brings it all together:

https://www.practicalnetworking.net/series/packet-traveling/packet-traveling/

To everyone else... and the OP... serious question. Lately I've been thinking of creating a "Network Fundamentals" e-learning class. The target audience would be folks about to embark on a Network Engineering career, or non-network engineers looking to learn a bit about networking. Would that be something interesting to you? What would you be willing to pay for a class like that? Knowing that it doesn't cover the full CCNA curriculum, but DOES communicate the basics of Networking to set you up to understand CCNA curriculum much better?

The content would be "like" the CCNA, except not cover the specific Cisco isms. It would be a network-agnostic course meant to teach Networking without bogging you down with each specific vendor's terminology, nuances, and marketing.

I would guarantee the class would be the best of its kind, I hope some of the rest of what I've put together would attest to the quality.

erh_ commented on
r/ccnaPosted by
3 points · 20 days ago · edited 20 days ago

When studying for the CCNA, I remember being confused by the intersection and disambiguation between these four terms [Classful CIDR FLSM VLSM], . Coming across many CCNA students presently, I see there is still some confusion about it. I thought I would throw this explanation of all of these out there in an effort to help alleviate some stress.

Classful

Classful addressing is how the early Internet was formed. IP assignments were given on the Classful Boundaries:

Class A     First Octect: 0-127     Subnet Mask: 255.0.0.0
Class B     First Octect: 128-191   Subnet Mask: 255.255.0.0
Class C     First Octect: 192-223   Subnet Mask: 255.255.255.0
Class D     First Octect 224-239    Multicast
Class E     First Octect 240-255    Reserved / Unused

The idea was, if you were a company that needed 200 IP addresses, a class C assignment would have been provided. If you were a company that needed 50,000 IP addresses, a class B would have been provided. And if you were one of the few companies that justified requiring over 65k~ IP addresses, you would be given a Class A.

Obviously, this lead to a lot of wasted IP addresses. If, for instance, you only needed 300 IP addresses, a Class C wouldn't cut it, so you would end up with a Class B and nearly 60,000 IP addresses would be wasted.

In reality, they would simply assign two class C's for the case above, but the above will serve as a useful example for how Classful addressing could and did waste addresses.

Classful addressing "evolved" into what we know of as Classless Inter-Domain Routing, or CIDR

CIDR

With Classless Inter-Domain Routing, IP assignments were not limited to their classes. In effect, the entire unicast range (First octect 0-223) can be broken up into any size network.

Instead of requiring subnet masks to be 255.0.0.0 or 255.255.0.0 or 255.255.255.0 in the IP assignment from IANA/RIRs, they could be anything -- and for simplicity slash notation was adopted.

  • If you need 300 IPs? You get a /23.
  • If you need 500 IPs? You also get a /23.
  • If you need 1000 IPs? You get a /22.
  • If you need 70,000 IPs? You get a /15
  • If you need 250,000 IPs? You get a /14 (instead of a /8 that you would have gotten in the Classful world)

The two terms above are in reference to IP ASSIGNMENTS. The two terms below (FLSM / VLSM) are in reference to how you assign subnets within your infrastructure, and whether or not your routing protocol also sends a subnet mask (this will make sense in a moment).


FLSM

Fixed Length Subnet Mask refers to a strategy where every one of your networks within your infrastructure was the same size.

Whether you got a classful assignment or a classless assignment from your RIR, you can deploy the IP addresses in a Fixed Length manner. For example:

You are assigned by your RIR this /24: 200.2.2.0/24

You have one Router, with the following requirements of IP addresses and designation of addresses within your assignment:

  • Fa0/0 - Needs 10 IP addresses - Assigned: 200.2.2.0/26
  • Fa0/1 - Needs 20 IP addresses - Assigned: 200.2.2.64/26
  • Fa0/2 - Needs 40 IP addresses - Assigned: 200.2.2.128/26
  • Fa0/3 - Needs 15 IP addresses - Assigned: 200.2.2.192/26

Because Fa0/2 needed 40 IP addresses, the minimum size for all your networks is a /26, and these four router interfaces have used up all 256 addresses of your assigned IP space, even though you only needed 85 IP addresses).

Obviously this is a huge waste. So the question that follows is why was this ever a thing? The reason: To save bits on the wire.

The early early routing protocols, aka RIP, saved bits on the wire by not included the subnet mask... the mask for all advertised networks was assumed to be the same mask assigned to the receiving interface.

Try it, fire up to routers in GNS3 (or maybe even packet tracer). Configure four /26's on one and four /27's on the other. Configure the link between the routers as a /26 and /27 respectively, but actual interfaces within the same /27 (aka, so they can still ping despite the non-matching subnet mask). Fire up RIP on all networks/interfaces and watch what happens. You'll see the router's perceive each other's advertisements as their own subnet mask.

The point being... (and this is often often confused in the industry)... FLSM is not the same thing as Classful assignments. FLSM is simply using one subnet-mask on all your router interfaces, on all your routers in your deployment

Whether the addresses you received from IANA/RIR came Classful or Classless is irrelevant to FLSM.

VLSM

As we can see in the example above, FLSM leads to many wasted addresses. The evolution of FLSM is what brought us to VLSM, or Variable Length Subnet Mask. Hopefully at this point you can deduce what VLSM is (as compared to FLSM):

FLSM is a subnet deployment strategy that requires all subnet-masks to be the same size. VLSM is a subnet deployment strategy that allows all subnet-masks to be variable sizes.

The same example above:

You are assigned by your RIR this /24: 200.2.2.0/24

You have one Router, with the following requirements of IP addresses and designation of addresses within your assignment:

  • Fa0/1 - Needs 20 IP addresses - Assigned: 200.2.2.0/27
  • Fa0/3 - Needs 15 IP addresses - Assigned: 200.2.2.32/27
  • Fa0/2 - Needs 40 IP addresses - Assigned: 200.2.2.64/26
  • Fa0/0 - Needs 10 IP addresses - Assigned: 200.2.2.128/28

Assigning the minimum IPs blocks to each network you've only assigned out .0-.139, leaving you a remaining 116 IP addresses for expansion. Not perfect, but definitely much better than FLSM.

(I re-ordered the interfaces to make the subneting easier, they are the same as above otherwise)

.


.

TLDR:

  • Classful addressing is an IP Assignment policy mandating IANA/RIR give out address blocks on bit boundaries (/8, /16, /24)
  • Classless or CIDR is an IP assignment policy allowing IANA/RIR to give out address blocks of any size, as required

.

  • FLSM mandates that every network within your deployment be the same size -- required for archaic routing protocols like RIP
  • VLSM allows any network within your deployment to be any size

Well, this ended up being longer than I meant it to. Maybe I'll polish it up and turn it into a blog post in the future... let me know if you would like that.

.

Source: http://goedhartvoordieren.nl/?page=r/ccna/comments/6mn70c/classful_vs_cidr_vs_flsm_vs_vlsm/

8

Hey all,

A few months ago I released the first five videos of a 7-part Subnetting Mastery youtube series.

Today (moments ago), Video 6 just went live. A few of you asked to be notified.

Subnetting in the /17 - /24 range - Part 6 of 7

Video 6 teaches you how to Subnet in the 3rd Octet. It uses the same process and cheat sheet from the first five videos..

I sincerely believe you can go from having no exposure to subnetting to becoming a Subnetting Pro just by watching these videos. They are all offerred at no cost, ad free, and without a mandatory sign up or paywall or whatever.

Video 7 will release later this week, or early next week. I'll make another "all encompassing" post on /r/ccna when it goes live.

Hope it helps! Any feedback is welcome!

8
comment
2 points · 22 days ago

Might I recommend this video: https://www.youtube.com/watch?v=BWZ-MHIhqjM

I think where you are there are a lot of different concepts that you are jumbling in your mind. I think watching that video will help separate the concepts so that you can (at worst) rephrase the question so we can better help you, or (at best) answer your question yourself.

3 points · 23 days ago

Consider each of those columns as two different sets of two different descriptors:

  • Inside vs Outside refer to the physical location of the real owner of the address in question
  • Local vs Global refer to perspective you are viewing the address from, in relationship to the NAT device

Both sets of terms can be combined into four different possibilities:

  • Inside Local – a host that physically exists on the Inside network, as seen from the perspective of the Inside network
  • Inside Global – a host that physically exists on the Inside network, as seen from the perspective of the Outside network
  • Outside Local – a host that physically exists on the Outside network, as seen from the perspective of the Inside network
  • Outside Global – a host that physically exists on the Outside network, as seen from the perspective of the Outside network

This image illustrates each IP address and its respective label:

https://www.practicalnetworking.net/wp-content/uploads/2017/10/cisco-terminology.gif

That image is taken from this article that goes into more detail about the Cisco NAT Terminology.

Hope this helps.

4 points · 25 days ago

Nice. I'm liking these wilson minutes. Keep them up!

Some feedback:

I love the timer, great addition. I love the animation for the Wilson Minute, good for branding. Also, I love the new Mic, it sounds much warmer and "closer" to the listener. Not as muffled.

(would you be willing to describe your setup? I have yet to settle on a final recording setup for my videos)?

I am completely OK with the video being 90 seconds, but the teaching portion being 60 seconds. Ideally it should all be 60, but I think this is an acceptable cost (and it significantly increases the range of topics you can cover).

I am not a fan of the new talking pace =/. I know you got lots of feedback to the contrary, but I think your "thing" was talking at a slightly increased tempo. It helps keep folks with ADD in tune. As soon as you talk too slow to someone who could keep up with faster, they zone out.

at 0:20~. "Here it is the third Octet as it is the first octet that is not 255" -- this could lead to incorrect answers. A /24, 255.255.255.0, will increment by one in the third octet, even though the fourth octet is the first octet that is not 255. This might be worth rewording to "Here it is the third octet as it is the octet before the first 0". This would correctly identify the third octet for both 255.255.240.0 and 255.255.255.0"

2 points · 27 days ago

The answers posted by /u/Iskaral-Pust and /u/zanfar are correct.

But if you (the OP or other readers) are interested in another take on it. This is the article I wrote about the EIGRP metrics and how the composite metric is calculated:

https://www.practicalnetworking.net/stand-alone/eigrp-metric/

3 points · 1 month ago

A trunk is a switch's port that carries more than one VLAN

A subinterface is a Router's port that carries more than one VLAN -- this is often called Router on a Stick.

This article will explain it in more details and with more visuals.

Original Poster2 points · 1 month ago

I think next time I'm going to put this suggestion in the original body. I let at least a handful of people know about this feature each time I make a video. Maybe I'll make a Wilson Minute about it. Haha.

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1 point · 1 month ago

Maybe I'll make a Wilson Minute about it. Haha

Ha!

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