Lecture - Classless Addressing

I so everybody has a workbook it's only like four pages I think eight problems or so if you're doing this online I'll be posting a PDF format or even a PDF format of this exercise you want to try to print it out before you watch the video even if you guys are going to rewatch this video later have an extra copy go through these over and over the only way you get better at subnetting is by doing them okay folks so I'll be posting this all in a week whatever we're on now seven or eight and the video if it does record I'm really hoping it is going to record will also be uploaded onto YouTube with anyone give me any trouble and we'll just go at it okay guys so no questions we're just gonna get ready to begin right in order for me to do this I'm going to step back a few and so in this particular example problem number eight I'm given a network address of 200 dot 175 dot 14.0 and let me open up that a packet tracer file and show you that class example when working with all week long and it shouldn't come as a shock over on the other whiteboard I basically had this logical topology written out correct you guys remember seeing that on Monday and then last week I drew it out saying to you this is it naturally we said we had four networks correct and for what you know right now you know that each of these networks this land this way in these two lands must have their own unique network address good about that if I'm given a network address of 200 dot 175 dot 14.0 it wasn't given to me by free I had to go out and buy it now typically rearranged network addresses by class a B and C and the class with the most host would cost the most it's that simple I always like to use the analogy of a trailer a home and a mansion which one's going to cost more which one gives you more space more room ironically more room for rooms for partitions right and a classful environment by the way which class would this represent Class C how did you determine that okay so you follow the human way of looking at it and you have your tables memory your classes memorized a goes from 0 to 127 B goes from 128 to 191 and C goes from 190 to 223 that works out well on the exam question is going to be maybe 8 points and I will ask you guys to explain classful addresses using binary correct clear about that now how do you know this was a Class C using binary Brian because the the first octet looks like this and binary so let's just take this and convert it into binary I have a 1 in the 128 correct I'm also going to get a 1 in the 64 it gives me 192 I'm going to get a 0 here and then I'm going to get a 0 4 so this was what 32 16 8 I get a 1 in 4 2 & 1 so I have 1 2 3 4 5 6 7 8 I'll bring up my spreadsheet later but for now this is just rough math I look at the very first bit on my very first octet and it's a 1 if it's a 1 what does that tell me to do next just leave it there ok then wait a second if it is a 1 here what do I do next go to the next bit right because if it was a zero would be a Class A if it was a one it could be a Class B or Class C correct so you go to the next bit if that was a zero in this place it would be what Class B but it's a one what do you do next because now it could be a d correct you go to the next bit and it's a what zero so therefore this is telling you that those three bits represent a class C license okay let's see Marcus can you do other problems before I can get back to you what's that it should be damn one makeup oh I thought it was exam 1 nevermind then I'll just set that up later for you yeah I'll send you an email tonight you're talking about the Cisco assessment yeah ok leave that there I'll just grab it later sorry about that yeah yep sorry about that alright so folks we see this is Class C and if I have a class full addressing scheme I can only use this address block one time correct so I can only use it on one of these networks I can't use it on the other ones why not what's the big issue if I tried to use that address block over again when I try to send a packet out imagine this this network is represented by this network address and these two networks are also represented by the same network address well my computer when it goes to send it will say hey the destination packet belongs to the same network that I'm in don't bother the router right we'll see that later but since it's not going to bother the router the packet will never get to PC five if that's what was intended to go so what must I do if i was doing classful addressing this must have another network address and that might be 200 dot 170 5.15 because when we determine class what can we deduce from our IP address now that you know this is a Class C what can you guys tell me about this address first three opt-outs of the network very good so if you need to get another classful address you have to call up the company it will be like look can I also buy 200 dot 170 5.15 can I also buy dot 16 and can I also buy dot 17 now that would be pretty wasteful for this network right here because the third thing you guys can deduce somewhere it's second thing right now right the second thing you can deduce after determined class is not how not only what part represents the network right but also what else which part is the host and therefore how many host a network can handle we clear about that so if I have a Class C address you guys told me at the very first three octets one two and three so let me just specify here first octet second octet third octet so first second and third is it okay if I just draw a line right here to divide the third from the fourth why do I want to separate the fourth octet from all the others because anything left of the line represents the and anything to the right of it represents the host so not only can you tell by looking at an address using classful techniques what the network portions of an address are but you can also tell me the size of that network how many bits in this particular example are used to represent the host how many bits total are used in ipv4 address 32 if 24 of those bits are used for the network then 8 bits I'm going to be used for the host now I'm going to teach you guys a formula that's been used quite a bit in computer science and it basically shows you the number of possibilities you can arrange those 8 bits to make unique results you take 2 because we're dealing with binary and you raise it to the number of bits in this case I'm going to raise the number of host bits if I take 2 raise to 8 host bits what am I going to get as an answer let's to raise to eight you need to get these places memorized 2:56 and that tells me how many total hosts this network can handle okay so if I have to raise to eight a Class C address can represent 256 total hosts what does that mean about usable which we call the sign of all address 254 so going back to my example with that wide area network how many hosts did I have in there only two and if I were to use a class full address and I spent let's say $1,000 a month for this address and all I need is two addresses I'm wasting a whole lot of addresses 252 to be exact plus I'm wasting a lot of money so the idea today is to break that traditional classful boundary and decide to draw this line anywhere to accommodate our exact needs we clear about that before I do that I want to finish up classful you said two things we can determine by looking at an IP address the host portion in the network portion and the number of hosts the network can handle correct what's the third thing you can tell me about this what's the default subnet mask I'm just gonna call it the thought mask for this address if we're a Class C well folks what is the purpose of a subnet mask I said this yesterday at the end of class to hide the networks are the host proportion the host portion from the IP address to reveal the network clear about that let's make this top row the IP address what is our IP address that were given right look at your problem what is 200 and binary we got a 1 in the 128 I don't know why we keep these around closed well here's green there we go a 1 in the 64 zero and the 32 0 to 16 a 1 in the 8 and then all zeros now I feel comfortable with this because I've been doing it for a lot of years now I don't expect you guys to feel comfortable with it but in order to get comfortable with it guess what you have to do and the same thing I had to do when I was first taught this technique practice practice practice right so I can say that 128 plus 64 is 192 192 plus 8 gives me 200 and that was the number I was looking to convert correct what are we going to do for the next one Ryan how are you going to convert the next number 175 what is it going to look like in binary I won in the 120s you need to tell me that because you guys could put a 1 here in the one I have no idea seems to tell me place so one in the 128 what are you going to do next a 0 and a 64 because we know that 128 plus 64 would give me 192 and that would go way over the 175 correct so now we have 128 what's the next one so if I take 128 and - so 175 and remove 128 from it what am I going to get it's going to be a 7 there going to be what 37 47 47 seems to be about right so 47 looks like I got to put a 1 into 32 right check my math folks I do make mistakes so 175 - ah what did we say 128 let me do that so I actually do some quick math here when I get a seven here and yes so it is going to be 47 so 47 minus 32 is 15 what's the number right before 16 fifteen the number right before 16 is 15 right look at what I did here if I know I'm looking for a 15 I know that a 16 would be a 1 followed by all zeroes correct what would the number be before one filed by all zeroes all one's done a zero that makes sense guys all right let's look at the next one Michael what do you think how we gonna do 14 I gave you the hard one not bad right which one of these numbers comes close to 14 without going over put a 1 in there subtract that number from your number you're trying to convert restart which one of these numbers comes up to that new number put a 1 in it and proceed correct another way doing is this quick addition what I'm gonna put in here for the host in you had the hardest one about a bunch you should get extra credit for doing this one my last class and they're going to beat up the extra-credit kid so you better be careful these other other students might beat you up all right so we have all zeros here because we just converted this zero up here into binary question was what is the subnet mask what is the default subnet mask let's make that in red remind me what octet represent the network part subnet mask can only contain either zeros or ones in it so I'm going to mass is designed to hide the host part from the IP to reveal the network part correct since an IP address can only consist of two parts a network part and a host part what are we going to use in binary to represent the network part a one what are we going to use in binary to represent the host part a zero if the first three octets represents the network part that I'm going to fill in those three octets with all ones how many ones am I going to put in here 24 and that's what we call the network prefix I told you the network prefix and the subnet mask are one of the same and what I mean by that is they both have the same task of telling a device how to calculate the network address the network prefix is telling me the first 24 bits represent the network hence the last egg bits would represent thee and what would I put in there for those bits so the default subnet mask is me simply taking these ones and converting them back into decimal which would be what memorize that just like you guys have zero memorized in binary memorize all once all eight ones are going to be 255 now I know what you're thinking to raise to eight gives you 256 we just did the math over there right how many fingers do I have guys include the thumbs if you want to be smart ten fingers but they go from zero one two three four five six seven eight nine we always count zero as a number so I have from zero to 255 which gives me all once correct so what's this going to be Evan give you another hard one and this one's going to be Bob I'll give you that one and what's the last one going to be so my subnet mask my default subnet mask for Class C would be 255 dot 255 dot 255 dot 0 folks the reason why we have to learn this is because we typically assign addresses from a classful block and then we subnet them second routing protocols like rip version 1 is a classful addressing protocol third you notice when we were in packet tracer or when you guys are configuring IP addresses on your end devices that when you type in a number like 200 dot 175 dot 14.26 the operating system does what automatically fills it out for you as 255 dot 255 dot 255 dot 0 what the default subnet mask be for Class B address 255 dot 255 dot 0 dot 0 what would the default network prefix be for a Class B C / 16 what about a Class A eight or 250 5.000 great about classful because we're going to turn it upside down and now we're going to something really different we're going to look at the problem and the problem is going to give us two pieces of conditions and we have to make sure that we meet these conditions the first condition they're telling us we need how many subnets now in our example that we've been using how many subnets would I need and where our subnets coming from well folks I'm being cheap I'm buying a class we'll see address I'm buying a trailer and now I'm having my family move in and I don't want to be sleeping in the same bedroom with them so I have four let's just say four there's four of us living in this trailer that we good about that and so I need four bedrooms so what I kind of do I could take the trailer and divide it up into equal four equals plus spaces that make sense and how would I do that look behind you do you guys see that a foldable wall there originally this classroom would be able to handle about 40 to 50 students originally school's having a problem with scheduling we had more instructors than we did classrooms so what did we do took a large classroom like this one and cut it in half what did I gain by taking this classroom and cutting in half and putting a door in each of these classrooms I could be teaching in this classroom while somebody else is teaching in the this is those people that are playing the damn lights with us all right same time that I'm teaching I'm taking this address block and I want to divide it up into four equal places so I can accommodate all my other local area networks correct using my topology that I showed you guys with packet tracer and this particular example they're telling me all you need is three rooms now I'm thinking this conceptually and I'm thinking they probably have two local area networks and one win to connect those two local networks guys getting the same picture to me what ideas took one router ins had two networks going off of that plus a win connected to another router hooked up to a network to come up with four total networks the other condition that they specified in that example was usable host addresses he says you needed 45 addresses you know what they did they said one two three four five six seven eight they literally went out and counted all the end devices they're going to make up their network and they came out with the number forty-seven now this classroom has 18 computers the other classroom has 20 computers if I am dividing the classrooms up equally what number should I use the classroom with the fewest number of devices or the classroom with the largest number of devices if I'm dividing the rooms up equally well let's think about it the other way around some days you drive to work and it's just you other days you take the family on vacation and there's eight of you do you buy a sports car for the days that you drive just to work and do you buy a minivan for the days that you go on family vacations which is only once a year or do you buy a minivan and you drive that all year-round by the way you can only afford one car sports car or the minivan I occasionally got a haul of family around to you know restaurants and everything else like that naives up here I'm going to go with sports card neck I got to protect my image but eventually you guys are going to become wiser and realize that having every kid sitting on each other's laps and a couple on the roof and a couple Linda you know trunk this is going to eventually wear tiresome it's what is it yeah I remember your marriage you don't have to impress anybody anymore so the minivans all in style correct you build to the largest network if I were to build my networks to only fit 18 hosts and then all of a sudden I had this other classroom that has 20 in there guess what I got to read Amala SH the whole thing and start over again you always start with the widest network and let that set the tone we're good about that folks if I give you this number you are to assume that that's the widest network okay I have two conditions one I need to make sure that if I am to divide this network up I need to be able to accommodate three networks and each of those networks have to be the handle 45 host addresses usable host addresses good about that folks this is a teeter-totter I can work from left to right or I can work from right to left let's keep our units and let's keep our direction if I'm working from left to right what area am i working in first so I'm right here and I'm working my way in this direction what area my in right now the network because you see all one's right here right when I cross this line because I can do that going from left to right now what area my own host I could do the same thing by going the opposite direction correct if I start here what area my in the host I have across this line would area my own the question becomes and always becomes this how many bits can you steal from the host to be able to accommodate a network of this size I'll say that again in order to create subnets you have to steal from the host in other words the line that I draw will no longer fall on an octet boundary that makes sense class able to draw the line right here class be able to draw the line right there Class C I drew the line right here I'm getting rid of classful addressing I'm going to create a custom subnet mask that's going to tell me the width of my network and the number of subnets so now I'm looking at this and I asked myself this is my host portion according to Class C the fourth octet represents the host I can only borrow bits from the host how many bits can I borrow to accommodate three subnets which each network being able to have forty five hosts let's look at it from right to left if I drew the line right here oh wait a million I got ahead of myself sorry guys I do this from time to time I'm so excited to get this done if I drew the line here doesn't make sense to draw the line there how many host bits that I leave behind none I made all 32 bits network Asst networks exactly right what's the definition of a network two or more devices connected together to share resources governed by the same set of rules the real common media there you go all right there we go now what if I draw the line leaving one host bit leftover and borrowing all these other host bits in fact at this point I would be putting all ones here thank you you hit that right on this is unacceptable because I only have two total addresses but how many addresses do I really need I need one for the network one for each device and one for the broadcast this does not give me enough you see this red number up here if I leave one bit behind I'm allowed with two hosts X 2 raise to 1 gives me two hosts clear about that this is never kosher you won't be allowed to do that at least not in this course so if I draw the line here notice I have all ones there and then two zeros afterwards correct that's as close as I can draw that line so what would my network prefix be / xxx which we tend to use for point-to-point connections correct because in point-to-point connection we only have two hosts so the key becomes as Ian mentioned you have to take your usable host address and add 2 to it which is going to give me what 47 and now I have to ask myself how many bits must I leave behind listen to terminology now how many bits must I borrow but how many bits must I leave behind to accommodate 47 hosts so mathematically this is where we expressed that 2 raised to what power will be able to accommodate 47 hosts make sense to the fifth would give me 32 right two to the sixth so to the six gives me 64 host addresses remember my example I said my largest network is going to be 60 correct in this problem it's 47 so that tells me 1 2 3 4 5 6 DC where I count that way 1 2 3 4 5 6 I hit right on 64 and I'm going to draw my line to the left of that and why am i drawing it to the left because I'm going from the right to the left we're clear about that that also means that I must put all zeros after the line because this is the host part and what goes before the line so what becomes my new custom subnet mask because no longer can I use the default mask to represent this Network so what becomes the new CSM custom subnet mask did these change just one change this one change so from now on the only octet that I'm really concerned about is the one where the changing your HAP is happening so what is the new subnet mask for this one this is in the what place this one is in the this one is in the so why do I take 128 add 64 to it and I get 192 good about that so my custom subnet mass is going to be 255 dot 255 dot 255 dot 192 I met one condition what was that condition I met condition number two usable host right now each of my subnets can handle 64 total host addresses 62 usable 64 total how many subnets or how many networks can I now represent in this new system translation how many bits did I borrow from the host for my subnet you always borrow bits from the host to make subnets it's no different than me coming in this classroom just drawing that desk and putting up a partition wall I had to take something out of this classroom to divide it I have to steal from this host I stole how many bits two to raise to two gives me what this two represents borrowed bits or what we call subnet bits because remember this line right here is my class full network and the area in between it are the subnets live an apartment building and it's a multiplex building we'll say it's building one like dorms on a college campus sometimes a given name sometimes it's give them numbers building one building to building three what if I write this notation down 1.2.3 let's say the first one is the building number let's say the second number is the floor number what do you think the third number would be room number and what if I put a slash two next to that you're half of the dorm room you're half of the dorm room right they see the structure here this is telling me the building in the building the rooms or the floors there's a telling me the size of the room is that clear I borrowed two bits from my house yielding four subnets good about that did I meet my first condition do I have enough subnet bits to be able to accommodate three subnets in fact do I have enough subnet bits to accommodate my network my packet tracer activity my packet tracer activity or that logical topology that I drew over there needed for networks do I have enough subnets to be able to handle those four networks do you notice as I steal more and more bits away from my host what will happen to my host size and what will happen to my subnet size hypothetically let's say if I steal one more bit replace this with the one now how many subnets can I handle how many bits did I borrow three to raise the three gives me eight right 8 subnets but now how many bits my left over with five there you go have it has that one down packed right so that means I can handle 8 subnets and each subnet can have a fixed width of 32 do me a favor what's 8 times 32 256 get rid of that calculator shame on you guys slap your right hand for even thinking about grabbing that Mouse why should it be 256 what's 3 plus 5 eight bits what's to raise to 8 2:56 if I say I need four subnets and if I take 256 divided by four what would the size of each network be okay I'll help you guys out using some monetary incentives keeping everything fair and equal so I don't show any favoritism in this class I've got a $20 bill and I want to make sure that everybody has their own equal fair share of this $20 bill we're all in here for an hour and 25 minutes so you guys should all get a slice of this $20 bill correct how many people are here sex hmm better spice it up a bit make the math a little bit easier for you guys because I know it's hard it's Monday I got a four additional ones here plus a 20 how many how much my - I have my hand right now 24 that's about all I have for this month so I got 24 dollars to get me through this month but now I'm willing to share it with you guys how much money you guys walk away each four dollars right because you took the six of you and divided by the total correct cord into a Class C address what is the total host address I'm allowed Class C 256 the original problem said three networks unfortunately what happened you take 256 divided by three you're not going to get a whole number you can't take a bit and cut it in half you can't take that switch there and hold it halfway and get 50% light and 50% gray in this room right is either going to be on or off good about that I can't do that here that's why I got to use my powers to come close to accommodating it without going under in this case does that make sense the more bits I steal the more subnets I get but what happens to the size of the subnets they become smaller and smaller so what I like to do to illustrate this is using a number line and you guys are going to love this number line because when it comes to the fourth octet it's really easy to work with however when it comes to using the fourth the third and possibly part of the second the number line gets massively long and it becomes overwhelming so we will look at it from a dot I saw a decimal perspective because easier for us to first digest it that way then I want to come back to that board and we're going to go back to looking at it from binary we clear about that so let me take a number line this number line is going to begin at what number folks and you give that zero let this number line only represent the fourth octet because they do not care about the first second or the third because that's what I bought I bought a condo I'm allowed to change the structure inside my apartment but I'm not allowed to change the building that make sense so I only care about what I can change if I can only change the fourth octet tell me when will this number line end at what number will it end how many bits make up the fourth octet so where does the number line end because it's not going to be at 8 because those are 8 bits close because we go from 0 notice these are solid dots anybody remember this from math class I had this like in third or fourth grade and always like baffled me what's different wean an open circle and a filled in circle if you know a solid circle you guys remember this from number lines what they say about open circles does it include it I have what solid circles hence its inclusive 0 to 255 no Michaels thinking that's a math class and think this is a networking course all computer stuff come from mathematicians now here we go I need three according to the problem three subnets but what am i given I only have to borrow two bits because if I bought a one bit it's only going to give me two subnets right to raise to 1 is 2 so I have to borrow 2 bits which will give me 4 subnets correct so far is it all right if I divide this octet into four equal places just like you guys are dividing the money into 4 6 equal shares so what's 256 divided by Thor I don't know if they're equal but you guys are getting the idea would this number be well with this number D and what would this number be if I'm going to divide 256 by 4 are you surprised to see 64 look right up there folks to raise the six gives me 64 wasn't that the width of our subnet if I'm borrowing - I'm leaving six behind so the width of each of my sub networks or my subnets are sixty-four DC I started with zero adit 64 - it add another 64 - it added another one you guys see what we call it fixed with the width of each of these areas are 64 wide let's call this one network zero let's call this one subnet what I'm gonna call this one and the last one no zero to nine right guys zero to nine what's the network address for subnet zero I'll start you off with the hard one I'll do the hard part 200 . 170 5.14 so what is the network address for this one according to yesterday's class I told you a network address has all what and the binary network address in the host part has all what all zeros okay so we're going to revisit this up in the front with the binary but the first number right all zeroes is technically the first number I didn't say first usable but the first number what is the very first number on this number line so why can't we make that the network address be good about that what's the network address for this subnet 200 . 175 . 14.6 t 4 and what do you think the network address is gonna be for this network notice that you lunge it's not changing dot 75 dot 14.1 what about the last network I'm doing the hard part for you guys 192 now that I got my network address for each of those sub that's what about my broadcast address I'll do the hard part for you guys whoa did you get that once a high it's usable but it's the last address of that range what is the last address for this range before you go on to the next network 63 so what's the broadcast address for this network I'll do the hard part I can't believe you guys you let me do this 1:27 what about this range and then you want what about this last range 2:55 solid dot and what about the numbers in between them what do we call them the assignable address block or the usable so when I go to configure this and once you guys going to be doing in your packages their activity my first useable address would be dot one correct and my gateway address for my last useable address would be dot 62 the number right before the broadcast address makes sense what would I put in for my subnet mask for this network here what's my new subnet mask so dot 255 dot 255 dot 255 dot 1 how do I teach my devices about these new boundaries that I'm putting in and my block in my house can I use 0 Zero's no longer applicable what was the new one I borrowed how many bits I borrowed two bits to make one two three four networks correct I borrowed the two high order bits so I borrowed 128 and 64 from the fourth octet 128 plus 64 gives me what about the subnet mask for this guy exactly why is it the same thing because they're still the same size I haven't varied it I'm not doing vlsm here all I am doing is fixed with some netting so all these networks are going to have the same subnet mask but they will not have the same network address they will not have the same broadcast address and they will not have the same usable host address that's decimal it's a nice little number line to divide it up it's beautiful because 256 is really easy to digest could you guys imagine a number line that's 65,536 decimals long and try to divide that up to a thousand subnets not didn't think you would so let's see what this looks like in binary so I'm going to create a new table when I come over here on the right side of my binary work and we're going to apply the principles so I have subnets I'm going to call them numbers creating a table always a good idea create a table especially if you're new to this subnet zero subnet 1 subnet two subnet three eventually we'll move from this binary table to a decimal table so that when you guys start generalizing all your work it'll make it easier for you to troubleshoot but for now we're going to do some binary I'm going to put the network address up top and the broadcast address underneath it but it's in binary I'm writing it in red whoops that's because my blue marker out just ran out I guess this is the fourth octet I don't care about the others because they don't change how many places are in the fourth octet one two three four five six seven eight how many of those bits out of those eight total host bits are being used to represent my subnets whoops the OL this is I gotta fix this so it's the same thing now how many bits did I borrow to make up for those subnets got the Christmas theme going on here DZ I'm color coding this the definition of a network address when it comes to binary terms is when you have all zeros in the hosts part you see that I wrote all my zeros in black to represent the host part of my address what's the red zeros represent the subnets everybody's good about that what am I going to write from a broadcast address what is the definition of the broadcast address the binary definition of a broadcast address remember the network address is used to group devices logically right they're used by routers to forward packets on if that's the case for the network address when do we use the broadcast address to everybody on the same network does that make sense now sometimes I unite caste by calling you guys out by your names but I can send a broadcast message because remember my packet header only has one destination IP address field right so I'll call you guys students that would be your broadcast name hey students listen up you have an exam next Friday that's not the case but just telling you that would be an example I can see the people on YouTube all right we're good about that that's group definition of a broadcast address when it comes to binary is when you have what in the host Oh once let's go on to the next subnet what would the next number be if this is my binary digits what would the next binary number be if I have zero zero than all once zero one interesting and then what am I going to get after that zeros and what happens when we have all zeros in the host part of an address and isn't this the boundary to the next network so what am I going to put for the broadcast address for this network and binary zero-one right followed by all ones in the host fascinating what's decimal zero in sorry what's binary zero and decimal do you see I have ignoring the black for a second just ignore these black numbers and just focus here I have a zero zero in binary what would that be in decimal I have a zero one and binary ignoring all these others what would that be and decimal ah you gotta ignore place you're thinking that's 64 as in like the network address is 64 but I'm saying ignore the others and just assume this is the first couple okay so zero one and decimal would be 1 what's 2 in binary and isn't it the next number in line what's 3 in binary and you guys see how I exhausted all the unique combinations for my red bits I can add 0 0 0 1 1 0 or 1 1 I cannot represent anything else without repeating myself and you see how the black bits just reoccur this is why I like memorizing things in binary because I don't really have to memorize too much decimal things look at it whack why did I go from 64 to 192 where'd that come from and binary I got a repetitive pattern look at it these zeros repeat each of these represent a new network address but where do they change where the red bits are if I to convert this whole number back into decimal I would get 0 which was the original network address of the first subnet correct if I were to convert this number back Evon you did this one including the black numbers as well now because I got to count the whole thing because I want to convert the whole thing back into an IP address I would get what 64 which was subnet 1 what would this be and what would this one be this allows me now to handle across different octet which we'll be doing tomorrow at the end of class ok I told you last 20 minutes we're going to be looking at the packet tracer grabbing this theory and applying it you guys should not feel comfortable with these numbers yet that's why there are 4 pages of this just for doing tomorrow and then over the weekend you guys be doing another set of those problems we'll be practicing those and practicing those until you're sick of doing them and we'll practice them more watch the video hopefully it's working over and over what you should feel comfortable with is configuring those end devices on your packet tracer question now becomes is what number should we use not where to put them but rather what to put in there so Ryan you're going to have to go to the public drives to go to my computer go to the P Drive open up the C SMT 1200 folder and copy the subnet file and then copy to your Documents then open it up for the people that are watching at home in blackboard you will have a link to the subnetting file just download it along with these examples folks we did number eight together let me just fill in the blanks in case you haven't filled them in yet class address was what default subnet mask was squared you have cubed you know 255 dot 255 dot 255 dot 0 custom subnet mask was going to be yes in the same 255 s but then at the end instead of a zero is going to be 192 what would the network prefix be how many bits do we borrow to make up for more networks to what was the original subnet mask 24 so 24 plus 2 gives me 26 would be the network prefix total number of subnets 4 because we borrow 2 bits total number of hosts that should read per subnet 64 number of usable per subnet 62 number of bits borrowed all right you guys are the engineers it's your network your administrating this there are four networks here which one of these four do you want to make subnet zero the one would switch a in it all right so I'm going to come over here and click on my documentation tool then I'm going to click underneath switch egg and then I'm going to type in subnet zero then hit enter and I'm going to type in network address of what's at 200 dot 175 dot 14.0 and what I'm going to put in there for the subnet mask 255 dot 255 dot 255 dot watt 192 no longer can I use the default the reason why I can't use the defaults they have to teach my end devices that this address block is now divided here's one division this is a second the third and the fourth notice I'm allowed to use first that represents subnet zero don't get your zeros and ones mixed up all right what are we going to make for the next subnet you want to make the one with the switch be not land subnet one joke all guys you tell me so let me click on the documentation tool I'm going to click underneath switch B and I'm going to type type in subnet 1 then enter network address what am I going to put in there for that 200 dot 175 dot 14.1 you can put in a Rhine for a subnet 1 64 by the white folks by now you realize by me doing this I'm not actually doing any configuration I'm just using it for documentation so I have a reference later what am I going to put for the subnet mask Bob I'll start you out with the hard part 255 255 dot 255 192 because remember I'm making all my networks the same width I'm making them all the same width guess what they get the same subnet mask so land 3 with the switch I'll make subnet to Brian when you're going to make this Network some note - what's the network address and we're going to make the subnet mask oh good now if you want to write if you want to move it just after you because I'm type and click on the white then bring your cursor back over click and hold and you should be able to move the label all right what's the last Network Michael have you do this one where is that last network at between the routers yep so I'll do a hard part for you this is going to be subnet 3 and the network address is going to begin with 200 dot 175 dot 14.1 192 and what you're going to do for subnet mask I know it's ridiculous folks but I promise you somebody's going to screw this up on the next exam and they're going to change it and make one have 192 the other one have them 224 remember I have not done any configuration yet here are the rules we're going to follow we go to configure rule number 1 the lowest end device in other words the PC with the lowest number on your network is going to be assigned the 1st usable address and then you will proceed sequentially so I sequentially from there on so the next PC would be the next address your default gateway is going to be the last useable address going back to my binary table what would the last usable address look like a binary last usable should it not be the number right before all once that means my last usable would have a 0 all the way down here and the very first bit last bit if you will that make sense so this one would be what what's the number right before 64 so this would be 63 but then the number I'd be 463 is 62 so this gateway for this network is going to be 62 what about this network over here look at the decimal number line over there if the broadcast address for this network is 127 what would the Gateway be because remember the broadcast address is the last address period 126 what about this network if the broadcast address for this network is 191 okay so let's begin I'm going to click on PC 0 now this is what I'm saying you guys should feel comfortable with going to the desktop tab clicking on IP configuration putting a dot next to static now this is the part you should not feel comfortable with because now you need to know what address to use I'm going to type in 200 dot 175 dot 14.1 am up to you this is my first device on my first subnet ah can we just make it one first usable address I'm going to click on the subnet mask and lo and behold I get hit with a default subnet mask so I'm just going to replace the zero with the what Evan 192 and what am I going to put in for the default gateway 200 dot 170 5.14.2 - on this network correct because I am on the first subnet let me close out of that go back to PC one desktop IP config click on IP address type in 200 175 dot 14.1 this is the next device on my network Bob if we used one before which one you're going to use now - what you're going to put in for your subnet mask Bob you got it and what about your default gateway sixty two just like the other device right because they are they're all part of the same logical network that's what we're doing right now we're assigning them the same logical network of two hundred dot 175 dot 14.0 all right Michael let's go over to PC two that's the other sort of the other subnet tell me the information you're going to use to configure this device so we have 200 dot 170 5.14 for the IP address followed by Oh what dot 65 very good because the network address for this new subnet is dot 64 so the next device is going to be 65 subnet masking with 255 dot 255 dot 255 dot 192 now I'm Michael what are you going to use for your default gateway so you're looking at the what's at 126 because he looked at the number line over there and you said 127 was the broadcast so the address right before that's going to be my gateway and the only reason why I'm making it that way is because that's me being anal following some kind of standard right some people use the first address to reach is their own but by being consistent it makes troubleshooting so much easier I'm just going to copy that because I know I have to do the same damn thing to the next device so for the next advice one's going to type in 200 dot 175 dot 14.6 t6 click on the subnet masks replace the subnet mask with 192 at the end and I'm going to add my gateway by pasting that in there all right Bryan PC for tell me your configuration method what did you put in for PC for it's on another subnet now so 200 dot 70 5.14 hard part's over with 65 was for the other Network right we're down here now yell at me we're down here all right 129 because we're on another network so we have another network address of dot 128 so I type in 200 dot 175 dot 14.1 29 and Brian what are you gonna put in for your subnet I mean sorry for your default gateway so 200 dot 175 dot 14.1 one-ninety because you know the broadcast is 191 all right so I click on PC 5 click on desktop click on IP configuration type in 200 dot 175 dot 14.1 194 no we can't do that this one's going to be 120 130 130 he's shaking his head at me sorry for your sorry to disappoint you dot 1:19 Oh what are we going to do about the routers you notice when I configured these I did my local devices and now I'm going to come back and do my routers and that's just me trying to be a little bit more efficient with my time I notice when I click on this router I can actually configure two interfaces at the same time so instead of clicking back and forth I decided to save my routers at the end but I need to pay attention you need to focus on what interfaces represent what network so if I hover over a red dot connected to the router it should tell me what interface is plugged into that router that represents this network I have FA 0/0 that represents the land of router zero then if I come over and hover on the other red dot which should be a serial connection so that should read a little clock because let me know this is the dcen s 0 / 0 / 0 so it's telling me it's the serial 0 / 0 / 0 let's click on R 0 so router 0 let's click on the config tab over on the left I'm going to click on the fast ethernet 0/0 before you can do anything with this interface you must do this and I always tell my students when you learn the i/os commands it's real easy to remember this command to turn on a port you type in no shut it's real simple remember because if you don't have a port turned on you can't use it hence no so you can remember that it's not going to work for you if the port's turned off hence apply the technique of remembering put a checkmark next to the on box you guys remember that when it comes to chapter 10 or chapter 11 now that I turned on that port and remember this interface represents the private LAN what did we tell our end devices that this gateway was going to be for this network 200 . 175 . 14.1 member on subnet zero what was the last usable address should be 62 right I told the other devices on this network that the way out of this network is going to device 200 dot 175 dot 14.6 t - I'm teaching this device that you are that man to go to to leave this network let's click on the subnet mask it adds a default forming so I got to replace that last zero with a 192 and at this time I'm going to click on my serial 0/0 and what do you think I'm going to do to this interface before I configure it turn on remember this interface had the little clock next to it hence I'm going to accept the clock rate of 2 million and what are we going to put in for the IP address for this interface remember this interface is on another network so I have 200 dot 175 dot 14.1 it's on another subnet you could do 254 you could also have done what 193 it works for me and what are we gonna put it for the subnet mask notice this time you click on it it automatically put it in there how did the router know to do that because you configured another interface on this router with the same three octets as this interface so the router had to assume since no two interfaces on the same router can represent the same network had to say oh they must have subnet at this so calculated it out and said oak the next network address must be this so hence 192 make sense - but it's not like that in the real world close out now you guys get to teach me Brian I'll start with you we're going to go to router 1 just let you know subnet - sorry subnet 1 is going to be on fastethernet 0/0 subnet 2 is going to be on fastethernet 0/1 and subnet 3s on serial 0 / 0 / 0 okay so I want you to configure the gateway for subnet 1 so I click on config I click on fastethernet 0/0 what's the very first thing I do turn it on what's the next thing I'm going to do which is what 1:26 what are you going to put in for yourself in that mask so the IP address was 200 . 175 . 14.1 26 subnet mask of 255 dot 255 dot 255 dot 192 looks good when I come over and click on fastethernet 0/1 haven't I haven't heard your voice in a while and if your mom's watching these video she's going to be proud of you what's the first step Oh first step there you go he didn't want me to say the magical key phrase remembering this did you alright now the next thing yep so the IP address would be that one seven five to do oh you don't much of a choice here because we already told the other devices what the default gate was going to be so when I'm in subnet 2 I said that hmm my range went from 128 to 191 191 being abroad you got it and if you click on the subnet mask did it automatically fill out the right subnet mask for you because we already configured the first interface all right let's click on the serial Ian you've been sitting there laughing at Evan so now I got to pick on you with the first step alright now here's a surprise what's the next step no not in this case sorry loser no kitty yeah we do but turn it off yes very good so you redeemed yourself now I can make you a winner my last class they were calling each other's losers so it just sort of trickled over alright now what are you gonna do for the southern that mask yeah sorry thank you so now I'm a loser 200 . 175 . 14.1 side of the router now on the other router you made dot 254 correct so you can't make this one dot 255 because that's the broadcast for that win so what are you going to make it so you're going to go back to the beginning we can do that we can make it the whole spectrum we're going to also made it 253 to each is their own it works for me and the subnet mask should up here correctly so I put 200 dot 175 dot 14.1 93 let me close out of that I have all green lights question can PC zero communicate with PC for rather stuff we have to teach the routers about the network's doesn't know about hmm this might make a nice interesting exam question can pc3 talk to PC for I'll give somebody extra credit if you could tell me what command in the iOS to verify that this network is in the routing table as well as this network in that network remember this router knows about the directly connected networks from now on I don't want here directly connecting networks I want to know the network addresses so what should be in rar ones routing cable 200 . 175 . 14.6 t for right because that's the network address for this one what about this one 200 . 175 . 14.1 28 what about this one 200 . 175 . 14.1 92 let's click on router 1 let's click on the CLI command it's our CLI tab hold the control key and hit the letter z here's your extra credit opportunity so hit enter tell me what would i type in here to display my IP routing cable close five more seconds or three two show space IP space route so Brian you're really close just n IP and lo and behold you see our original Network block right the class Vil but notice now it has a slash 26 and it says its subnet at three times each of those network addresses that we talked about so yes PC three can talk to PC four because the router has an entry to get there but PC zero cannot talk to PC four because router one and router two of our router zero do not know about the the other's network okay save this we're done I'll see you guys tomorrow in class your homework assignment tonight is to do problem 9 doesn't count against you if you get it entirely right I'll give you extra credit okay so bring it do your work on the graph paper or whatever way you do it notice you're not going to be structured into a text file you guys can write it the way you naturally would write it just bring it complete it tomorrow it's problem 9 it's on the next page page 20

Channel: Nicholas Andre

Views: 14,143

Rating: 5 out of 5

Keywords: Lecture, Classless, Addressing

Id: fnpDURJnGQ8

Length: 80min 55sec (4855 seconds)

Published: Wed Oct 17 2012