Routes That Must Win Twice | Cisco CCNA 200-301

[Music] [Music] and welcome everybody is fantastic to have you here on this beautiful Pacific time 4 p.m. afternoon stream my name is keith barker if you're brand new to the channel holy schnikeys I'm glad you're here I'm having a bunch of fun of these live streams and I'm always amazed at the adrenaline rush I have which is like near panic attack like 5 minutes before it starts so that's done that's already happen so I was getting out of the shower and I have my cell phone I'm playing the countdown timer and that music's going I'm thinking oh my gosh we're gonna be online here in a few minutes but you know when I get here it's fantastic to join you and our topic today for this livestream is why routes have to win twice and let me give you a big picture and then we'll talk about the details and then we'll demonstrate in the lab environment for a route to make it into the routing table it's not just a walk in the park an easy day I mean there could be imagine that we have a router and it's got four or five let's do let's use an analogy let's imagine that we have four or five friends that are telling us what we should do they're giving us their opinion about what we should do and if their opinion differs like one person says do this another person says do that a third person says do something totally different there's a decision that has to be made like okay what are we gonna do we're gonna follow this person's advice or that person's advice or none of them the same kind of a situation happens with a router a router can learn routes in many different ways they can have a directly connected network so if we took a router and took its interface and said dear mr. interface no shut down bung and it's up great great the interface is up and then if we said your IP address is 10.1 7.7 with a 24-bit mask it then realizes or believes that it is on the 10 1 7 Network and so as a result there's a there's a network there and that a directly connect connected network has that an administrative distance of 0 which means pretty good it's like golf the lower the better but if we have other route sources like static routes or routing protocols their advertising routes to us if we're getting advertised for a specific route let's imagine a 24-bit Network take your pick maybe 10 10 10 whatever it is if we have multiple routing protocols or options for learning that the way we were going to determine which one we're going to put in the routing table to even be used possibly later is by administrative distance it's like golf they'll lower the better so you're saying Keith that if I have two different routing protocols and they're both advertising to the single router 10-10-10 that network with the 24 bit mask that the routing protocol that the local router considers to have the lower administrative distance like OSPF is 110 Yeji RP is 90 ripp is 120 whichever has the lowest administrative distance that's the one it's going to get in the routing table and that's it so part of the pecking order of the game that a router is going to play is making sure it chooses the the route that has the lowest ad administrative distance and it's gonna put that in the routing table now the next question might be well what if what if we have the same routing protocol like OSPF it has an administrative distance of 110 and we have we're learning about the same route twice but they're from different environments what do we do then if they're both administrative distance of 110 the next tiebreaker if we're learning about the same exact network 10 10 10 and it's a 24 bit route and we're learning it from two different sources and they have the same administrative distance the tie breaker then is the metric for the cost so that's the little number that when you look at a routing table has the administrative distance first then slash and then the cost or the metric and so if it if we're learning about two different routes like having two friends that tell us hey here's what you should do and they're both differing information do we believe them both the same if the answer is yes maybe have the both same that administrative distance and then we look at the second factor which is cost how painful will it to be what you say versus what you say and in a routing table we want the best possible routes to show up and so the one that has the lowest cost or metric depending on the routing protocol to OSPF its cost with things like rip it's a metric it's a hop count so the one for the lowest cost wins and that's it that's how we get into the routing table now to demonstrate that I thought we'd go over to the white board and take a look at a topology and actually see it in action let's take a look so in this one on this white board I've got a lot of routers there's probably too many for this demonstration but we got it looks like a trout errs here and we've got this network right here which is 10.1 7.0 that's off of gig zero zero and router seven is directly connected to it so what I would like to do is first of all add now this is something you probably don't want to do you know too much in a production environment or even practice too much but I think we had to use rip to begin with and rip is a routing protocol of routing information protocol as the acronym will use rip version 2 and just gonna put it on all these routers give it like two minutes to converge cuz rip isn't that fast it's a distance vector routing protocol it's no longer on the CCNA but it'll do for our demo because it has an administrative distance of 120 so for router eight learns about that network 10.1 done with rip it's going to have it administrative distance of 120 and in in absence of a better source of information about that one network it's going to put that route that has the administrative distance of 120 in its routing table and then what we can do is we can actually use a different routing protocol it has a better administrative distance and then see those routes bounce out so let's do that first and let me clear this up and let's go ahead and bring up a command line and this almost looks like a command line and now it does you know one of the secrets that I think is really important is that if we're doing repetitive tasks over and over and over again it makes sense for us to to automate that so if we had scripting or you know controller we use api's and communicated all at once but short of that let's use notepad and just put in rip on all these devices just so we can see the r8 on the far right hand side of the topology is going to learn about that network so I'm gonna bring up notepad I've got it right here handy and some of the commands think about what are some of the commands we'd use to configure a router if you're brand new to Cisco at the CLI we type in configure terminal but the cool kids they just do config space T because it's unique enough and the Cisco router knows what it means so config T or config terminal it basically means I want to configure from the terminal I'm sitting at duh great so then if we're gonna do rip we'll sit we'll go in the router configuration mode for rip so we'll say router rib I always when I think of RIP I think of Astro on the Jetsons like I was a cartoon from like the 70s and rubber rope George alright so router rip that puts us in the router configuration process and then let's do a no Auto summary so by default rip summarizes the classful boundaries on Class A B and C addresses so that's just so it won't behave that way and then we'll also say we want to run version two just because version one blows chunks just to be clear on what I was mean in there version 1 version 1 doesn't advertise masks and so you can't use variable length subnet masks with version 1 and so we'll use version 2 and then we'll use a Network statement and this networks the network statements are classful unfortunately but what this Network statement means is please mister router any interfaces that have the 10 network on them please enable them for rip and share those routes inside of the routing process and that's it so we'll just go ahead and copy all that with a control C and go to router 1 paste it in check for typos and then we'll just put it in all the other routers I'm just clicking on each of the tabs and right-clicking and the in the console to paste them and we are good to go so in a few moments and it might take a few minutes we are going to have full convergence between all these eight routers and and distance-vector routing protocols like rip version 2 you aren't very smart they periodically just say here's everything I know here's everything I know to their neighbors or to whoever happens to be hanging off the network they don't form formal adjacencies they just burp out their information periodically and eventually the whole network will converge so I think I think I spelled the long enough for ripp to converge let's go take a look at rather eight so the the Turk here is our the goal here is I want these routes here from router seven that ten one seven network I'm waiting for it to show up over here on our eight so we're gonna focus on that one specific 24-bit network in our demonstration that'll make it easier to see the network to change and focus on one address versus like oh there's twenty networks just focus on one at a time and that makes it easier to troubleshoot and also to learn so let's go back to the CLI and list of a show IP route which will show the show IP routing table on the cisco router all right looks like we're fully converged this is show IP route and if we want to see just the routes that were learned via rip we can do a show IP route and tag on the keyword rip and that will just limit the output doesn't change the reality of it but let me see output to just showing us the RIP learn routes fantastic and if we all they're all they're all tens so another thing we could have done is to a show IP route for 10000 and that will show us all the ten anything routes but because that's all we have here in rip it wouldn't really limit our output so here's our network right here and this is re telling us dear mr. administrator as he gets out his pen dear mr. administrator I learned a route via the RIP routing protocol that's what that R is on the far left the decoders the codes are up here on top the network is 10.17 with a 24-bit mask that's the route I learned to be a rip and I assume says the local router it that the administrative distance for rip any rip learn relatives 120 by default and with administrative distance if there's two different sources advertising the same route the one with the lower administrative distance is going to be preferred and put in the routing table and the one with the higher ad wouldn't so it's like I got a struggle to get in and now we have no competition because when I rip running this flyer right here is the metric that metric is going to vary just a little bit based on the routing protocol you're running in the case of Eid air people and it will focus on a rip in the case of rip it's a hop count it means how many router do I have to go across to get to that destination Network and so if I had to advertisements for the ten one seven Network and they were both from rip and one had a metric or a hop count of five and one had a hop count of seven I would put this one that we're looking at in the routing table because it's a better route so administrative distance first if it's a tie then cost or metric and then if it's a tie and we have to we'll put both of them in because we're gonna say well two routes there have equal ad equal cost let's put them both in we'll take a look at an example of that on our for in our topology in just a moment this is also indicating that the next hop if we ever need a forward a packet says r8 to get to the ten one seven anything we are going to go ahead and forward it to our good buddy ten to sixty eight six and we are gonna use the egress or exit interface of Fast Ethernet 4/1 so that's what all of that means and we say fantastic and then we want to try it so we could do a trace to ten dot 1.7.2 pick up my notes here okay dot seven is the address right here off of our seven so we're gonna we're sitting here at our eight and we're doing a ping or a trace whatever we're gonna do all the way across and here's what I would expect to have happen I would expect that our eight let me use a temporary color for this so I can easily expect that our eight we already saw his first hop is here and then our six our six is gonna make its own decisions based on what it believes to be true about forwarding for that network and so it's also going to forward this direction but when we're doing IP routing it's hop by hop it's like hot potato each router takes the packet figures out what the next hop is Arion caps lates at layer two to put the next hops layer to address on shoves it out the door the exit interface the egress interface and then the next router gets it this is the layer to address it's its own address looks at layer 3 header it says oh this is destined for a certain network looks at routing table makes a decision and that continues on so here's what I think is going to happen I think that the routing is going to go like this on fortunately and I'm saying unfortunately because this yellow link right here is fastethernet so the high road across the top is gigabit and this is fast ethernet but from a ripp perspective all it is doing is counting how many routers do I have to go across so here it's going across our 6r for r3 r5 to our 7 and we'd have an additional router actually an additional two routers in the path if we took the high road so you know distance vector routing protocols that are just plain Jane like rip version 2 I'm not getting a lot of love these days because they're not helping us out using our most effective paths but that's what we expect the path to be and we can verify that with a quick trace so we'll go back to the CLI and we'll do that so trace 2 10.1 dot 7.7 and I think I have a host PC 7 sitting off there at 10 yay so PC eights out there as well and so PC 8 if we took a look at PC 8 that's its IP address so we could do a ping a trace to tend to oh we're on PC 8 so on PC we do a trace 2 10 1.7.10 what that is I believe that is the IP address of this PC or in the far left so this is PC 8 on the far right doing a trace all the way across to PC 7 just to verify true and end connectivity yep fantastic so this part right here destination port unreachable when we do a trace from a Cisco router or from a Linux box it actually at the layer 4 uses a UDP header and so it's looking for some port and when it hits the final destination if that port isn't open or the server is not listening on that port it says I'm not listening on that port and so it that's why this message is coming back we also have options in some applications in some software to do traces or with to a trace and implement a TCP based race or an ICMP based race so Windows by default will do ICMP as its trace like a like ping instead of UDP or TCP also it uses the TTL so basically the trick is sending out sends out the first three packets with the T tail of one the first router and the ha and the path kills them and that's why we get those messages back saying hey I killed your packet and that's what happened here with the first path and then we sent it out again the PC did with a TTL of 2 and then router 6 killed a packet and sent us the three messages and that's what we're measuring when we come back is the I killed your packet messages from each of the routers in the hop based on that expired TTL so that's the magic of trace route which is a fantastic tool alright so that is oh yeah that is rip and all of its wonder and now that we have rip and r8 has learned about the 10.17 network via rip let's go ahead and use something better so something better would be almost any routing protocol um we could use EA GRP which has an autonomous which has an 80 and a administrative distance of 90 OSPF which has an administrative distance of 110 and either one of those is gonna beat out rip because rip if we do a show command again here on our 8 I just scroll up a little bit for that 10.1 dot 7 Network come on you all I have to do is beat 120 so let's do OSPF because that's a CCNA topic and let's still give us a little practice with that so let's go ahead and configure terminal and router OSPF process ID 1 and then we'll specify a network 10 dot anything and then the wildcard mask that says we care about matching on the 10 but we don't care about matching on the second octet or the third octet or the fourth octet and mister router once you've had a chance to look at all your interfaces and see which interfaces begin with 10 we want you to put any interfaces and any directly connected networks to those interfaces in area 0 I think that's really all we need so I will go ahead and copy that and let's pump it into each server there's one two three four five six seven and eight now it may take a moment for OSPF to figure out the D rbdr situation and have full of Jason C's but what does once that's up this could be very quick fact let's do this let's have a little fun you want to watch the RIP routes die debug IP routing this is a winner by the way in my CCI lab this saved my bacon more than once so debug IP routing is gonna give debug or log messages and debug messages anytime there's changes to the routing topology or the routing table on the router so as the OSPF neighbor ships come up and we start exchanging LS a's and everything's converged we're gonna have routes learn by OSB though they go we're gonna have routes that are learned by OSPF they have a better administrative distance and we'll see the other else being pushed out in fact let's see here oh yeah let me just give it a few more moments to converge completely and then we'll look at some of the output every that'll do on debug all look at this that's that's our route it's like I was gonna search for that that's gonna search for that network but a few months ago that route was in route router eights routing table as a rip learned route with an administrative distance of one tenth of one twenty and now what this debug is showing us that hey we have a closer meaning better administrative distance for 10.1 dot 7.0 we're flushing one route that's the old rip route that's being flushed out and the OSPF learned route is being put in it's a it's a jungle out there you know the routing table whew competing to get in and this helps demonstrate that the way a route gets into the routing table if there's conflict for the same exact network the conflict is going to be solved by taking the route that has the lowest administrative distance and that's the route that's going to come in now there are some defaults that we should be aware of for admin distance and some of those defaults are a directly connected route it has an administrative distance of zero I mean that's that's that's a pretty low golf score if you've got a golf score of zero probably somebody's cheating right cuz you have to hit the club it hit the ball at least once but that's what the default is and then if we have a static route and I'm gonna clarify that because later and CCNP and CCIE you'll want to know this if it's a static route that has an IP address as a next hop then the default administrative distance for that is one because you can have a static route that's actually pointing to an egress interface like on a point-to-point you can do it on Ethernet too but it's a bad play and then that's that would be actually be seen in the routing table as a directly connected route even though it's the static route so a typical CCNA static route with our normal next hop is going to have a ad of 1 and then as we go down let's take a look at some others that Arcanine EA GRP it's not on the CCNA but that's okay you're still gonna see it in some production environments with specific applications like dmvpn with an overlay of EA GRP anyway it has a for interior EA GRP routes there's an administrative distance of 90 and then next we would have OSPF I'm just using once they're gonna be most popular would be 110 and then rip would be 120 and if we're talking about border gateway protocol external BGP routes we'd have a 80 of 20 by default and internal BGP neighbor ships that we're learning BGP routes that way that would be 200 for CCNA not too important these would be I think more than enough that you need to know for CCNA now these are the defaults you don't you don't have to use these defaults you could go into a router and simply say hey dear mr. router from now on I want all OSPF routes to be considered an administrative distance of 70 or 90 or 250 whatever whatever number you wanted to put there so these are the defaults and good to know so let's go ahead and we just watched we just watched OSPF beat out rip the debug actually explained that or gave us a visual representation of that so let me hit the right button here and let's take a look at the routing table the show IP route and there's our 10.1 dot seven network so there's the administrative distance first 110 which is the default Pro SPF followed by the metric which in the case of OSPF is cost oh yeah you know what I did wrong I mean yeah yeah I forgot to put something in pretty important let's look at our topology and bring up a pen so with rip our 4 if our 4 was going to try to get to the 10 dot I think this is 10.0 that one network up here rip would have seen and I didn't show you i we just overlaid OSPF on it but it would have seen seen this path as equal cost because it was two hops away going on path B and path a and I think we've seen that before in previous stream so rip is not that smart but OSPF because the reference bandwidth is 100 megabits they take my face out of this because the reference bandwidth is 100 megabits per second Mbps effectively what that means by default is that every interface that's 100 megabits or higher it's gonna have a cost of 1 so with that with that older and default reference bandwidth OSPF also sees this as equal cost paths but you know what that's perfect for our demonstration because I can show you how if the router believes that it has to equal cost paths the admin distance is the same for a specific network and the cost is the same for a specific network it can put both of those in the routing table so let's do that that'd be fun and let's take a road trip up to our 4 and then we can correct that also so here's our 4 we'll do a show IP route for OSPF learn routes yeah right here at the top the 1001 Network the admin distance for these two routes is 110 and let me go ahead and use a little option there there we go to highlight those in that kernel emulator you can hold down the Alt key and actually do sections that you want to highlight and that's what I'm doing there so for this route for 1001 it's got two routes and it's got ten Edmund distance of 110 for each and it's got a metric or a cost of three for each and that's because of the faulty reference bandwidth I shouldn't say faulty but older default reference bandwidth that still ships with Cisco IOS so we can verify that the show IP ospf press enter and this is going to show us that the reference bandwidth right here is 100 megabits per second so I need to fix that I think I want to fix that so we have one clear winner and it's gonna win because it has a better cost over path a than path B so let's go into router OSPF again we already put in the network let's use the auto cost reference bandwidth and we'll specify 1000 meaning 1000 megabits per second that way our gigabit interfaces will look like a cost of 1 and the faster the interfaces look like a cost of 10 and OSPF will have an accurate picture because it has all the LSAs and it can build the best path to the network based on the actual costs of the interface so I will go ahead and right click copy that and go to r1 and it's warning me to make sure I do the same reference bandwidth across all devices in my network and I am alright so now if we go back to our for which a moment ago and I'll scroll up to take a look at the out pay here a moment ago r4 thought that for this network 10 dot zero dot one it thought that it had to equal cost paths with r2 and r3 being the next hops respectively so that's here's our 4 right here and our 2 and our 3 it will consider to be equal paths either way but now with the auto cost reference bandwidth saying that hey gigabit has a cost of 1 but your fast ethernet has a cost of 10 it's going to change its opinion I'm expecting it just how the fastest path to from r4 to r2 to r1 not consider the slower path through our three even it didn't make it to the winners table now the winners table is the routing table so that's what we're looking at here and we'll just do a quick up arrow key a couple times for a show IP route for OSPF learn routes and there is our new updated route for 1001 and it's now just using the next top of through 24.3 and that's because the other route that goes this is going through 24 10.0 225 to r2 is the next stop and that's because the previous route that went through our three or that fast ethernet link is no longer contending is like so sorry you don't make it to the routing table you don't win all right so we've taken a look at two options are two examples of getting into the routing table one with rip or there's no competition then we brought in OSPF which had a lower administrative distance and so those routes were put in the routing table we did a debug to verify by by rip learning route it's been nice knowing you and then next I'd like to share with you even a lower administrative distance and I think an example that would be using a static route because if we go to our eight and you and I put a static route on our eight for that same network the 10.17 will verify that in the lab if we put a static route and we just make the administrative distance lower than 110 it's gonna win so by default a static route that has an IP address for a next hop it's gonna be a default there's gonna be a static it's gonna have a ad of one but we can control that by tacking on whatever ad we want that specific route to use so let's do that and we'll go back to our eight just do a quick clearing of a few things and just show IP route for OSPF learned routes that's enough there's our route right there so 10 one seven just to remember where we're at that's this Network down here off of gig 0 0 for R 7 and we are sitting at our 8 over on the right-hand side of our topology just to make sure we're all in the same exact place and what we're gonna do is we're gonna simply replace this R add a static route that says the metric is that ad is gonna be something less than 110 so we're gonna go into configuration mode IP route and we'll put in ten dot 1.7.1 4-bit mask just like that will specify the next hop of 10.2 um yeah I'm using the same next top because r8 between you and I alright doesn't have a lot of options it's like you're my we could actually use a default gateway and point to our six and that would be fine because the only way our eights moving traffic to anywhere outside of its directly connected networks is our six so we'll put in the next top of ten 2.68 dot six and then here we can tack on the distance if we want to distance metric metric by default that's gonna be one but we could go ahead and use like 109 boom and that would work because that's lower than 110 so we do it do show IP route OSPF for OSPF learned routes and then we go down a little bit I don't see it 10150 yeah I just told it please show me the only the OSPF learned routes I'm like I don't see my route for ten-hut 1.7 like yeah you told it not to computers they do what you ask them to do not always what you wanted to do let's do a show IP route I'll see the entire routing table that way including the static route that just beat out the OSPF route and that's right here and that's because the lower administrative distance so check this out this is fun little fun game if we hit the up arrow key a couple times and we have the static route again but we changed it to 111 which is a worse ad than the OSPF learned route and press enter that updates that static route and now we have a static route with an administrative distance of 111 and if we do a show IP route and hit spacebar and take a look at that one specific route it's now back to the OSPF learner out there if we did a debug IP routing it would show us that swap say what the OSPF learned route is better than the static route and it put it in the routing table so that route that we just created with it artificially high ad that's an example of a what do you call it Halloween you've got those little ghosties that are going around floating static route that's what it is that's so a floating static route is a static route that's in the big but it's not in use yet until the primary route for whatever reason goes away and then it's the next best option and it will go into the routing table so we have a floating static route I'm gonna go ahead and put it back as let's go ahead and put it back as how about a well we just press ENTER right here check this out now it's a the default of one that'll work I'm not sure I had to think about that so hard and if you go back now and look at it here is our static route and there is the administrative distance right there which is one so one AD by default okay so in our goal and our in our journey today we wanted to cover two things the theory of why does the route have to win twice it has to win once to get in the routing table and that's all boils down to what options do I have as a router what routes are being advertised or communicated to me and if I have a tie for the exact same route let me go ahead and use the one with the lowest ad and it will go in the routing table if I have two exact routes with the with the same ad then it comes down to cost I will put the one route with the lower cost in the routing table and if they're both the same they both go to their outer table and then we can do multipathing and load balancing across and the router can actually use both of those paths hopefully it's gonna use consistent paths and Seth plays a part of that but that's the general idea now as a side note just as a side note and that is if we're running a routing product like AIG RP it has the ability to go ahead and do proportional load balancing on slightly different cost paths so if an the edge ERP router has two or three or four interface or interfaces and routes should say that aren't they're not equal but they're all they're all feasible meaning they're they can all be used without creating a loop in the network we can actually configure unequal cost load balancing with Yeji ARP so it'll use multiple unequal cost paths and it can do proportional load balancing but for CCNA there's no EAG ARP so that won't come but just wanted to be aware of that that OSPF and other protocols are going to equal cost load balancing yo G or P being a corner case okay secondly now these routers these routes have duked it out there in the routing table based on the lowest ad and now which one is going to be used this is a fun discussion and it's pretty short too but actually calculating it is fun to do and that if we're going to do the answer to that is if you and I are a router and we see a packet coming in in that IP header there's no mask information in the header of an IP packet it has an IP version 4 source address and an ipv4 destination address and as a router we're looking at unless we're using reverse path forwarding or something we're looking at the destination IP address and we're gonna make a forwarding decision for it so we look at the destination IP address and then we look at our routing table and we look for a match now there is an opportunity in a routing table to have one packet that matches against two or three different routes that are different lengths it's true I'll show you here in a moment which one are we going to choose which one is the router choose the answer is it's gonna choose the longest match what do you mean Keith the longest match I mean that if it's sort of like imagine that we were handed a package and we were asked to describe that package and we had five choices if we have three of those choices that describe the package but once the most accurate our most detailed we might choose that it's sort of like that with a router when the packet comes in if there are several packets several routes in the routing table that match that that could be used it'll choose the one that matches that has the longest match so that means a 24 bit network and a 25 bit network and a 26 bit network as a route if they all matched it would use the 26 bit Network the longest match in the routing table wins sometimes people forget that it's a very distinct two-step process the first step is who gets into the routing table great once that's all settled and the routing table is stable and sitting there the next question is which route in the routing table is used if there's multiple possibilities and if none of the detailed routes match doesn't mean we're gonna drop the packet no because if we have a default route that's what the default route would come into play it's like the routers like yeah I just looked through this is like computer hardware very quick decision but hey I just look at all my routes nothing matches here as far as detailed routes no 16-bit networks no 12 but networks no wait bit networks you know what I'm gonna go ahead and use my default route and make the routing decision next packet please so even if we don't have a detailed route that matches there could be a if there's a default route on the router it's gonna use that to forward so I thought what would be fun to do is let's create an environment where we have multiple routes that we can play with that would all match and then I'm going to share with you how we can predict as humans because it's important for the real world and for certification to be able to do this I also will warn you that if you haven't been through the subnet Saturdays with me yet I would encourage you to check out that playlist on the YouTube my youtube channel and there's a separate playlist for subnet Saturday I've also integrated that as part of the master playlist for CCNA either way you want to consume that is great with me but we are going to be using something referred to as block size in our calculations today which was a couple subnet Saturdays ago so if you if you haven't yet gotten to that give yourself a huge break and and a huge margin and come back to it after you've actually looked at that subnet Saturday series all right so let's let's do this let's create some routes Karen and it's saying Keith you got to create a new layer for that I can do that that's good and M and me one channel and moment here there we go there's a new layer let's create four new routes on our eight and these routes are gonna be ten 1.7.2 for which we already did I guess we are do that one hey we're one down and let's also create ten 1.7 0 / 25 and 10.1 7.0 / 26 and 10.1 7.0 / 27 so we'll create those 4 new routes and all of them if we point to our sixes FA 4 / 0 interface as the next top they'll all work but the question is which one will it use and the answer is always going to be the router if these are all viable routes they all match a packet so PC 8 says I'm going to ping 10 dot 1.7.1 ping PC 7 which is 10.72 10 if we do a ping to that address the router gets the packet all these four routes match but it's going to use the one that has the longest match in this case it's going to be this bad boy right here it's a 27 bit route but I'll show you how to calculate that and we'll walk through it together so let's create those four static routes on our eight and then we can walk through the process of actually configuring or verifying which route is going to be used so we'll make a road trip back to our eight and on our eight let's just do a show IP route static I don't see what we have first not a bad idea before we start configuring so we've got our one static route already great and oh hey I have an up arrow key and I'm not afraid to use it so let's go ahead and create some new static routes and that is IEP route 10 one seven zero with a 24 bit mask and if we did our binary table and we put in a 1 bit for the mask in the fourth octet come see me in subnet Saturday well it would be a 128 boom and if we did it again and we had a mask that was two bits in that fourth octet it'd be 128 plus 64 and that would be 192 boom and if we were gonna sit to pay for it or if I'd and if we were gonna do a 27 bit mask which is three bits on that last octet the mask for that third that last octet would be 224 and so the binary and the decimal for that I leave to your discretion in the subnet Saturdays I think you'll enjoy it and that's that's what this means now I have a question I'd like to ask you and then we can look at the results and that is are all these routes getting into the routing table I mean earlier we created a route and we had like an administrative distance of 109 and then 110 and then and then as we put those in it was overwriting the previous ones so here I've put in four routes well three additional routes the question is aren't they the same network is it is the route routing table gonna treat them differently and the secret is they are not the same routes one the one we did earlier is a 24-bit route then we did a 25 bit route and a 26 bit route and a 27 bit route and so all of them because they're different routes are going to make it into the routing table at least that's my hope let's check it out let's do a do show IP route and let's go ahead and just say static because that's what we're gonna focus on here's our static routes right there all four of them 24 25 26 and 27 bit masks so if we were to go to PC eights and I'll show you the topology and let's imagine that we're over here at PC 8 and we ping 10 1.7.10 which of those routes is going to be used and one way of just finding out from the router which is pretty cool is we can do a do show IP route and we can put in that IP address of 10 1.7.10 and press Enter and it tells us here's what I came up with I've been working on this all night says the router it it is showing us right here it's using the slash 27 why why this last 27 all of those routes match by the way every one of those static routes could have been used I mean they were all matching on the first 24 bits first 25 bits first 26 bits first 27 bits they all matched but it chose to use the longest match and so I thought it would be an entertaining game for us to play how do we know which which IP address is going to use which route because there's got to be some networks I think you'll agree let me go to the big camera there's gonna be some destination IP addresses that don't match that 27 bit network and there's gonna be some IP addresses going to ten dot one dot seven dot something that don't match the 26 bit network and the 27 bit network and that way they would have to use the 25 bit network or the 24 bit network and I'd like to share with you how you can calculate that and get it right every time let's do that right now we're gonna start off by and get my pen and let's start off with the this this mmm what we want to call it we want to call it it's really the powers of two bit well the bind the depth of values for an octet of data set 1 2 4 8 16 32 64 128 1 2 3 4 5 6 7 8 checking my work there's a period there everything going that direction represents the third octet everything going this direction represents the fourth octet because we're starting to slice and dice in that last fourth octet so if we were going to take these routes and I'm just going to put the like this last 27 and then we'll put this last 26 and this last 25 and this last 24 so there's our our masks my question for you for those of you who have been with me in subnets Saturdays or you just know this because you've been working in the field I am so impressed there are so many amazing people on this channel who have volunteered to help moderate the discord server who have volunteered to help answer questions and help their fellow humans it's just it's amazing so my hats off to everybody who's volunteering their time and talent and effort into helping other people so regardless of how you might know it about subnet Saturdays is certainly one of them I'd like us to write out what the block size is for a twenty-seven bit mask and I'll put right here a block size what is the block size for a 1/27 what is the block size for the last 26 was the block size for a / 2.5 in a block size 4/24 and I'll go ahead and just circle those here and what we could do is say well for a twenty-seven if the 24 bits ends here at this period and then we have a 5 26 27 the block size would be 32 right there and for a 26 bit Network 24 25 joysticks to be 64 right there great so far so good for us last 25 it would be 128 this bit right here if that's the least significant bit of the mask 128 and 424 oh we got to go back 1 because we're now on the the third octet and that least significant bit of the mask is a is a 1 you erase that real quick is a 1 and so the block size here is just gonna be one in that third octet instead of the fourth because that's where that belongs so if we were to calculate and here's the network Tim got 1.7 for this last 27 maybe put this in a slightly different color maybe 10.1 7.0 / 27 and let's do this last 26 10.1 7.0 / 26 I'm starting slow and 10.1 7.0 slash 25 just these are the routes right here and then 10.1 7.0 it's last 24 so how is that going to help us in identifying you know based on the IP address that's being sent which route is gonna be used hold on to your hold on to your socks because this is going to be one of the easiest things to do with the block size in this network right here ten dot one dot seven with a 32-bit block size the next network which I will put in a slightly different color let me go ahead and use red here the next network is gonna be 10.17 dot plus the block size 32 and I'll put a line there for the ten one seven zero twenty six with a sixty-four block size the next subnet can be 10.1.1.1 Lock size 64 and for the slash twenty five you separate that for this last twenty five the next subnet is gonna be 10.17 dot add the block size that game that game never gets old it just keeps on truckin and the benefit of doing this is because now we can identify the ranges of IP addresses for those subnets like lickety-split let's do it together so on this network 10.1 does 7.0 with the 27 bit mask the starting address is going to be dot one it's plus one more for the first so the the network address you can't use as a host address because it's the street name and the first IP address to be dot one and then the last address is gonna be one less than the next subnet if the next subnet 32 you can't write into that space so it be through dot 31 and I will say for this discussion that slash 31 is definitely the ipv4 broadcast address for the subnet so really we can only assign dot one through dot thirty two hosts but that's the range of addresses that belong to this subnet all right next one subnet that ends it has its last 26 the first address is going to be well if dot zero is where it starts this can be dealt one again then the ending address is going to be one less or the the range is gonna be one less than the next subnet so to go through dot 63 again 63 being the broadcast address for 10 1 7 0 slash 26 and then as we continue to go down here this network but this last 25 the first address is still going to be 1 through and then the next subnets 128 so you back that off 1 and the last subnets last IP address for that range for that subnet is 127 and again these three on the far right are the broadcast addresses so for this bad boy 10.1 7.0 his block size is 1 so and it's in the third octet so the next subnet and I'll put that in red just to make it consistent it would be 10 that's not red that's not red let me see if I can do better 10.17 excuse me the block size is 1 and that third octet so 7 plus 1 more would be 8.0 and that would also make the range for this address the dot 1 through dot 255 and that 255 is definitely once again the broadcast address for this subnet so let's talk about what we've done here we've identified that the router when it gets a packet and looks at its routing table it could have potentially multiple routes that made it to the routing table but which one's going to use it's going to use the one that has the longest match so if we sent a packet from PC 8 and we sent it to 10.17 oh I'm just let you take off my face so if I want to see that if we have a packet that's that PCA to send attendant 1.7.10 which is the PC 7 on the far side off that network that address 10 it fits in all of these and as a result it's gonna this routers gonna use the longest match which is gonna be the slash 27 if we were to send a packet to 10.17 dot let's pick something higher than 31 and under 63 let's go ahead and do 60 and I'll play here you can use the slash 20 seven if we send an IP packet to that address the router would look at its routing table and say Oh dot sixty it doesn't match on the twenty seven bit Network no no but the next longest match is this bad boy right here with this last twenty six so it would use these last twenty six route and if PC eight were to send a packet to 10.17 dot and we'll pick something up higher than sixty three let's say ninety the router would look at this matches it would have two matches they would be the 25 and the 24 bit network it's used the longest to be just last twenty five route one be used again and then for the last one ten dot one dot seven dot and use something higher than 127 something less than 255 let's go and use 200 that's in that range and that would use this last 24 because because my friends it uses the longest match it has when it gets an IP packet and with the benefit of South Cisco Express forwarding and caching it makes these decisions and also does the Rhian capsulation at layer two and forwards those packets with the appropriate frame information as well very very very fast so I don't know I just think that maybe maybe we should try it and verify based on those four addresses verify which routes are actually used and then that can help cement that information and about oh I get it it's the longest match and as you become better with subnetting and calculating subnet ranges which we're doing in subnet saturdays you'll be able to do this whether it's in a production environment or at a certification exam or just as a freaking party trick to impress your friends all right let's test this out I'm gonna leave this screen up I am gonna use little button magic here so I can work on the underlying screen and leave that up and let's do a do show IP route and let's pick on the we already do the first one in fact I'll hit the up arrow key that's ten dot 1.7.10 and this should be based on our calculations this should be using the 27 bit route and we'll press ENTER and there it is okay one down three to go next one up show a show IP route for 10.1.1.1 that 7.62 last octet and put 60 and press enter and what we're expecting here is because that 60 is no longer in the range of this last twenty seven but it's in the range of this last twenty six that's the route it should use because that's the longest route and I'm not gonna lie I was hoping that would work I was like please be please let the math work here and it does alright and let's go ahead and do the next one with the up arrow key and this time well ping 90 yeah oh do show IP route 490 which is showing us the route that would be used and ninety doesn't fall in this last twenty seven it doesn't fall in slash twenty six but it does fall in this last twenty five and the twenty four but this last twenty five is longer so we're expecting this last twenty five route to be used for forwarding packet to 10.17 dot ninety sure enough its last twenty five one more and that is a dot two hundred and because the dot 200 is it doesn't match this last five seven or slash five six or slash twenty five the router saying oh this is easy easy one for me I only have one match here and it is the slash twenty four so let the up arrow key will back off that last octet type in two hundred and press Enter and there's our 24-bit Network all right I'm gonna be just straight-up honest I'm super happy all that worked out after the proxy ARP thing the other day it's like oh come on that's not fair it's just trying to demonstrate a simple principle and proxy ARP is kicking my rear end alright that is what I wanted to cover in the live stream today about why does a route have to win twice here's the summary it has to win once to get into the routing table and if there's conflict meaning I have lots of sources static routes dynamic routing protocols the various flavors that are trying to get routes into my routing table there's only so much room at the top of the podium at the winners table and that winners table is the routing table and if there's conflict about the same exact network it's gonna go ahead and use the one with the lowest golf score also called administrative distance if the administrative distance is the same for these two routes and then uses the one with the lower cost if the cost is the same for both OSPF and well I'll focus on most PF OSPF is gonna put those both in the routing table and use those as equal cost paths for multipath routing now once all the routes get in the routing table which one's get used if a packet comes in those packets do not have any information about masks at all all it is is a four octet IP address that's it and so the router says okay let me see if you match anything I have in my routing table and it looks for if there's multiple matches it's going to use the longest match and forward that packet if there's no matches for explicit routes in the routing table but it has a default route it'll use the default route to go ahead and forward that traffic and that's that's how it works yeah pretty tickled it worked actually I thought it would I've done this a few times in my career but it's always nice to see it again in a production environment and see it work okay so here's what I'm gonna do I'm going to take a short break just for a few moments and I would encourage you to get grab a drink real quick or something else and when we come back I would like to go and do do QA and here's my my request for QA if you have anything related to what we covered today about how routes get in the routing table or which routes are selected although I think we've covered it if you have any questions about that specifically please let me know about those questions first and then secondly if there's any other questions regarding CCNA related topics let me know I also have a discord server that I've had a lot of support for being moderators and people just volunteering their time way to go to thumb's way up and so if you want to join that as well I've got six categories for suggestions one for each of the domains for the new CCNA 200 301 and that way if you have recommendations like oh I'd love to see this or this in the right topic I can kind of verify what is wanted the most and then focus on that make sure include those in a live stream so the format I'm intending on is for subnet Saturdays we're gonna keep going till that is like a nice complete library and for CCNA Sunday's gonna keep going that until all your requests that match the blueprint have been done and then after that we'll come up with something else creative but that's my objective it to focus completely on the CCNA and help people who are working on their CCNA or even Network+ because a lot of same concepts in doing well and improving okay that's that's it so also when you ask questions to save me from scrolling all the way back up I'm a one-man operator here if you would if you had a question asked earlier that you'd like to ask me if you could ask it again now with an at keith barker and that way it'll show up in a bright color for me so i can see it verify it and make sure i get to those questions I know I've seen holy schnikeys I have seen in the corner of my eye so many questions being answered by so many people I am so grateful CCNA is worth it it is I if I look back on my career force with Cisco Systems and the things I learned the skills I have with Cisco it's all been worth it and right now I'm on a new learning curve with software fine networking you know API is and using postman and DNA Center and authentication tokens and that's gonna be my world for the next three or four months just ramping up on all that stuff as I'm involved in a lab are two labs at Cisco live in June where I'll be one of the Proctor's on those labs to help people who are brand new to it understand it so I've got a few months to really jump in and master that content well the same time making CCNP content at CBT Nuggets which is what I love do that's my full time gig alright I'm gonna go ahead and step away just for a few moments I'll be right back and then we'll go to some Q&A for for a period of time as long as you'd like to hang around alright thanks everybody I'll see you in a few minutes [Music] life is a winding road no telling where it goes driving through days and nights won't stop for traffic lights even if is falling down I will keep on searching for my heart you can say oh that's my and I will keep on holding my head high even the sky is falling down alright I am back if there's any questions my Q&A screen is right here so if I'm looking there I'm looking at those questions and I would be happy to take any if there's no questions also that's also very very cool I have a link in the in the notes right below the video it's gonna be posted that has the invite for the discord server so if you'd like to jump on that and join us there we'd love to have you it's a great place to make requests and also to discuss and just check out the rules channel before you jump in and make sure you're comfortable rules and what the the naughty list is all about and avoid those things and you'll be great okay all right office to crazy is asking what is ping from interface so I could elaborate on pings so in an ipv6 so if you would clarify the office too crazy for me and I will be happy to elaborate on the correct answer if we're doing a ping with an ipv6 address with a link local address we have to specify which interface because link local addresses aren't routable you're just off of an interface so you have three interfaces on the cisco router with ipv6 and you do a ping to a link local address it needs to know which interface you want to ping from there's also options for pinging where you can ping and if you don't put any options it's going to ping from the routing table from the closest interface to the destination but maybe we have a client network behind us and we want to source a ping from that interface so we can do a ping from the not that so if we have gig 1 0 here and behind this gig 0 0 to our clients we could do a ping out that way and we could source it from either the IP address or the interface of gig 0 0 so those are 2 interface options for pings actually 3 if that answers your question that is fantastic and Sophie on is asking do they put all the routers in area zero I believe I did because this is CCNA I I did I use a script so earlier let's go take a look earlier and this is still here I'm gonna hide that for a moment and bring my mic over so you can hear me so if we do a show this is a great way show IP ospf database that'll help confirm it yeah so this is area zero and I've got router l essays from all eight routers which is a very quick way of confirming that all these routers are in OSPF area zero and the script I use which is right here also confirm oh I erased it so earlier when I dump them all in I put everything that began with the ten inside of OSPF area zero so great question and yes I did in CCNP and other higher level certifications we would split those up into areas that way not every router doesn't have to have to have the full database for the entire network you can just have the LS a synchronized for the area it's in and that makes a huge network more manageable from an OSPF perspective we can also do summarization and filtering it something called an area border router okay Dinah's asking what was the tcp traceroute tool you mentioned how does it work so in this environment let's go back to the this is a virtualized environment that I might playground that I use quite a bit it's also one that we use at CBT Nuggets and these are just little virtual machines and if we want to do a trace from here and I'll do a I'll press press ENTER so trace without anything is on this virtual machine is just giving us options on what we can do so by default this uses UDP at the transport layer layer for when it sends a packet basically to a destination that we specify and then it sends three packets out with a TTL of one they all get rejected by the first hop router because it says well the TTL expired and then it does it with a t-tail of two for three packets and then it doesn't for a t-tail three and and that's how we're mapping out the whole network each router is like oh I killed your pack second router I killed your packet third router I killed your packet and in the background that's what's happening and at layer 4 it's using UDP this this machine this virtual machine this little teeny itty-bitty virtual machine really thin is using has the ability to use ICMP so if we did a on PC let me go to PC 8 that's where we did our trace before so if I owned a PC 8 and I'm gonna do a trace and just press ENTER to get little context-sensitive help here so the syntax is traced the destination great and then the option so if we did a normal trace like that it's using UDP the end device oh it didn't care 57 dot ok hmm it didn't bark it's using UDP by default but this time it didn't complain about port not available let me let me ping to 7 that's the interface address of our 7 on the far left-hand side of our topology yeah it doesn't like it so the actual PC just said whatever and this device the router is saying I don't have that port open whatever that port was so that's what this port destination unreachable message is if we did this and get my context-sensitive help again I'm a bit trace and then we do that same command again to 10.1 dot 7.7 and this time we do a - P and then we say protocol 1 that's literally the protocol number for ICMP so TCP is protocol 6 right there in front of me and UDP is protocol 17 in decimal or 11 in hex depending on what you're looking at and this says please use ICMP and so from the end device it just looks like a ping request instead of looking for a UDP random open port it's actually looks like a ICMP echo request and then the router says great nothing to do here except respond with the TTL expired message so Cisco routers use UDP by default and Windows computers they use and Linux uses UDP by default and Linux and Windows uses ICMP and I think I think there's an option if we went to a router let's go to our 8 and on the router for just show not show if we do extended ping no if you extended traceroute yeah just give me a chance to think I rewatched my stream from yesterday that's what I was doing with proxy Arif was like I was watching myself think through the solution like what is what the heck is going on here so we do trace your out and press Enter that's gonna give us an extended trace route so we're using IP target address of 10 1.7.10 that's the PC on the far left-hand side of the network enter source address so if you wanted to source it from a different interface then let's take a peek then this four slash four slash one interface right there we could we can source it from gig gig 0-0 if we did but by default you can use the closest interface towards that destination based on its routing table so we can leave that alone so I'm gonna press Enter numeric display and that's fine timeout probe count time to live port number okay so this is asking us okay for UDP for your tracer out what port number do you want to use so I was thinking there might be an option for TCP or ICMP but it appears that it's just port number yep so there you go and there's our trace come on back all right and it timed out that's what the asterisk represents there are some great hacking tools that can do trace commands that you can throw in specifically you know ICMP or UDP or TCP and I would just do a quick Google search to find some of those also if you're going to use hacking tools please don't ever use a tool like that on a production network that you don't have explicit permission to do it because that could be considered a violation of security for most companies so any hacking tool play with them at home practicing at home or on networks that you're authorized to practice with practice them on Scotty is one of the tools where you can send almost anything you want with any kind of configuration I've used that in the past and Kali Linux just has a boatload of tools built in all right so I think hopefully I answered that chin and let me take a look at anymore okay can you please explain how to configure ipv6 on a Cisco router having first 64 bits from the ISP so you could have one big network if you're if the ISP give you see is the ISP may give you a block of addresses or you'd have thousands or hundreds of thousands of subnets or networks to play with but if they give you one IP address you could do subnetting for that so what I'd like to do if that's something you're very interested in in the discord channel go ahead and put that in there six sections for CCNA suggestions from you that's what it's for and if you just put that in a suggestion that's where I'm gonna go almost every week and look through and say okay what is the common theme or are people up voting this what do people want to see from a CCNA perspective and that's what I'll focus our next dreams on so if you do that for me I'd be happy to prepare something formal for you and then walk you through it and office to crazy saying can't Keith can you elaborate and and because I don't I don't remember what the first part was you'll need to type that in a little bit further context so I can elaborate on the right thing all right some great responses from the community I appreciate that and take a look is there a possibility to go through the feasible successors and how it works and go deeper than just the theory about it I err I love the feasible successor unfortunately it's not part of CCNA anymore so it won't be on this channel yes I want to focus I want make sure everything that I'm saying and doing and helping with is driven for CCNA and but I'll tell you what I will we should make another channel on discord and have it say other topics other than CCNA in fact to my list and then we can go I can take that look at that and just not lose them I can have that history of what people want what they're looking for and then if I run out of every possible topic in CCNA which I don't think we will for a long long time then we can go ahead and tackle some of those so if you make that recommendation let me give that channel at a discord like other recommendations for topics if you could add that I'd be happy to consider that once we get the CCC name they out of the way Thank You Cisco cybertek for that recommendation and let me see here okay I err as I hope I'm pronouncing that right here I think you explained how to pronounce her name and I I think I did it correct when you explained it and I hope I'm doing it correctly now that you know I love you by air thank you probably great work one of the things I'm kind o sophie-anne thank you very much for the super chat thank you for all your great work one of the things I'm kind of struggling with is equal slash unequal load balancing with OSPF and EIGRP the great news about unequal cost load balancing is that OSPF doesn't do it yeah GRP can do it but OSPF doesn't OSPF is simply using equal cost routes load balancing across those equally or fairly equally the actual algorithm it's using is based on the type of flows going across it with SEF but there's no any no unequal cost load balancing with OSPF at least that I'm aware of okay dan is asking hey Dan how do you trace from your virtual network to physical network on different subnets I would follow the maket direct well so if we're going between subnets how do you trace from virtual network to physical that works on different subnets if we do a trace not every not every router or firewall if I'm configuring it it's gonna be willing to respond to the TTL expired a good firewall isn't gonna give you that information I shouldn't say good many firewalls when they're configured or trained hey that TTL expired I'm dropping the packet I'm not telling the hacker or anything because they're trying to figure out the path through the network perhaps so we might get timeouts but assuming that every device in the path it's a layer 3 routing device which could include firewalls if they're responding when the t-tail expires and they send back an ICMP message to the source saying that we killed your packet that's literally going to show you each of the hops through the network so going each router each router interface represents a different network and so that would be representative whether using multi-layer switches or physical routers that would be representative of the path is taking based on the routers that respond back to you with exactly who those hops are and where they're coming from all right Frank past the CCNA routes which before the exam change nice wow that was there's a lot of people pushing at the last moment and I'm happy for everybody who succeeded that is fantastic okay Porter 4e is asking based on the router choosing the longest match to route the specific so routers when they're making a routing decision they're not really considering subnets all they're it's like a blind decision based on the routing table so you could have like we did we created four static routes that really pointed to the same area there's but when it's looking the routing tables just considering okay here's the destination address which of these routes match and I'm gonna use the longest one actually what it says is here's the destination address here's my match it's the longest route that matches explicitly I'm going to forward so based on the router choosing the longest manage to route traffic would there ever be a time when the longest match is not met there are some corner cases hmm that's a great question if we're doing policy-based routing where we're simply telling the router based on these conditions do this that was certainly excluded from choosing the longest match on its own with OSPF there are some really interesting corner cases on OSPF types but they would be different networks so I take that back a longer match I unless you're doing policy-based routing or have other controls in place I can't think of an example where the longest match would not be used if the longest match met the match the packet coming in could be wrong but I don't think so I think that's exactly how it works and Frank is asking what's your view of viral I don't if that's for me I'll answer it from somebody else I apologize viral is a great tool version two is coming out for CCNA all you need is packet trace 4 it is free go to netacad com sign up get a free account download packet tracer start having fun with it it's fabulous so for CCNP level stuff it's actually quite useful because it can do a lot of things that packet tracer cannot so my opinion viral is it's 200 bucks I on a license for it I don't use it all the time but I have it in the event that I need it Oh Keith can I give you the discord link yes yes I can let me go ahead and grab that in fact if I could have one of the some of someone who wants to do it was on YouTube right now for this page in the messages below I pinned a comment with that link so you can go to there or if something wants to grab that and just paste it into the chats that would be awesome too either way it'll take you right there thank you for asking I'm new to discord I was going through the security and I was like I had a few questions and I built the server and I just hit a clear settings clear permissions I thought oh I don't know if I so anyway long story short I spent many many hours building tearing down building tearing down the discord server and as and still getting feedback from the moderators thank you very much on things that hey people can't see the rules oh that's me and going in and or oh hey as a member I can only add one comment every five minutes or something and I had accidentally put on slow mode for one of the channels so learning experiences yep learning so I'm grateful and we'll get it all dialed in it's gonna be wonderful what book would I recommend for CCMP encore the way I do books is if I've read one and I had a recommendation I would tell you I currently have a subscription force like Safari online or maybe now so Riley or something else that gives me the electronic access to the books the one that I use is the SIRT guide the official sort guide for CCNP for encore so I would I would use that one also if you go up to Amazon even if you don't buy it from Amazon depending on your feelings about that but I buy lost stuff from Amazon it's just so convenient but good Amazon do a search for your books for encore maybe put the exam number in and then see which ones are rated I really enjoy looking at the ratings including the ones people who don't look at one star ratings should because if like ninety percent of five stars and you have one for one star or you for one star you just look at those and say oh why are this why is this person disgruntled or why is this you know find out what their thing is and maybe maybe they wrote the other book and they're competing or whatever but if most people love it and there are people who bought the book and there's more than just like five evils you know ratings I would trust that so if they have like 50 or 100 ratings on a book and their people are saying yep it was concise it was well done etc etc that's that's a good decision point and that's just a flexible answer that can be used on any new decision for a book but I usually go to the official guides I find them very convenient not always I used I've written some books for Pearson publishing and Cisco press many years ago and it's tough you know there's a lot of information that goes in there and hopefully everything's fact checked and sometimes I'll see something I'll read something and I'll say that's not how that works occasionally so I don't have any specific examples but I have seen one in the in the last week or two I've seen a couple like that it wasn't gross errors just little things and it happens and so I would give the authors if it's a generally great book I would give them a lot of kudos so this this shirt says I've got your back that is a question that just came in so that's what that is I have another shirt that says I wear this periodic table shirt and it says I wear this shirt periodically I like the I like the humorous shirts my wife thinks are corny but they're part of my part of me and she loves me so I'm all good thanks for the question do you know okay if if if you want it to be a moderator and didn't get a link and you still want to be a moderator contact me at that same email address contact at the Keith Barker comm and express the desire to still be a moderator if that's what you want to do and I will go through those sometime in the next four or five days and I'd be happy to add more people who want to help and serve so if I missed you or if I didn't get to you please give me another opportunity to get you into the fold and add you as a moderator if you'd like to be so thank you thank you for that question okay another question can you provide discord details I'd like to join in addition this channel could be focused on Cisco CCNA 200 301 what about the new CCMP great question this channel is going to be focused on CCNA 200 - 300 on hard stop period and that's because there are I believe tens of thousands of people a month who are in some stage of preparation or wanting to learn more about CCNA and I'd like our channel I say ours because you're doing an amazing job of contributing I would like our channel to be synonymous with you know if you're studying for CCNA you got to go through the playlist from Keith and he's not monetizing it there's no ads at least at this point unless something drastically changes that's not going to change either he's there to help he's telling this you know the straight scoop giving examples you can watch them troubleshoot proxy ARP when that shows up and I would like us to be synonymous with CCNA 200 301 and I'd like your help to do it for no other reason than helping our fellow humans so once you get your CCNA come back stop by occasion I answer some chats and discord make recommendations on topics you'd like to see for CCNA and that is gonna be the focus it's important to have I'd love ccmp level stuff I love CCA little stuff but I'm focusing this channel 99.8% on CCNA Oh Keith are you gonna go over this is from office too crazy Keith are you gonna go over automation on this channel for the new exam yes I am and it's gonna be probably a couple months down the road because I discovered something interesting if a person wants to teach something clearly and really explain it so a person can get it including examples and demonstrations to really help that information sink in they need to know it first and I have been on the cusp of automation for a long time I mean I saw it coming and it was coming I understand this Deanne how it works but I had never taken the time to actually study it in depth which is what I'm starting as of last week so I'm going through the content the videos the dev net using D cloud using in postman I'm having so much fun with postman postman is a tool that you can use to test and work with your AP is an API and in the old days in the old days and this demo well the way we interacted with our devices was one on one with the console cable first and then maybe after we give it an IP address in the default gateway if it's a switch or an IP address on an interface and some routing information we can connect to it over the internet or over a network with IP using SSH from a terminal emulator one device at a time configure configure configure configure so that was our interface of how we worked with those devices to deploy hundreds or or dozens of devices it takes a lot of time so instead of having us as humans interact with those devices we have a controller that interacts with those devices and the language of love between this controller think of a control like a machine a computer that is communicating with your switch or your router your firewall or other network device and instead of using a console cable or instead of using like telnet or SSH it uses this special set of commands our special methods called API so all an API is an application programming interface it's the agreed to method for sending data receiving data between a controller and the network device so where do we come in as administrators well where we come in is we sit at a console that our we sit at a computer that has a beautiful interface where we can do intent based networking where we're just saying we want this to happen we want that port to be open we want this flow of traffic and then behind the scenes we're using orchestration which software that's making sure all that happens like if something goes wrong and the background scripts can be run and find out information and provide us an overview of what's going on and that's from the controller so the controller talks to the network devices the controller talks to us at our management interface and that's software to find networking and it makes a lot of sense but the key is with CCNA they want you to be at a very high level just aware like what I just explained of some of the concepts of that understand JSON which is not hard to you recognize it and what it does and why it works and that will help prepare you if you want to take the next steps into automation or you're working in environment where they have automation you'll understand oh yeah I get it we're not logging into each of the devices with the console we're not logging into each of the devices with SSH for the terminal emulator we're going to use some kind of an orchestration software that a management console that where the controller is talking to you and pushing commands and working with these network devices and we through a graphical user interface usually are going to be talking to that controller and then behind the scenes when the whole thing goes to we need to understand some basics about the API is the language of love whether it's Python and using Amal and other methods to actually communicate so yes the answer is when I become more ready to do a very clear job of describing at the right level for CCNA those pieces we are gonna have some live streams on that with demonstrations so thank you for that question I'm excited about to by the way I had a coach I coach I had a manager many many years ago named Ted and he was telling me about I forget how the example came up oh he talked about change and learning and he said when he played football or he gave me the analogy when somebody plays football like in high school there's gonna be some pain involved and the best way to get through that pain is embrace it and realize it's gonna be there and just work through it and the same thing is with anything new in life you want to play the guitar or the ukulele or the radio that's a joke or learn something new about networking or get your skills in the world of automation at least be aware of it there's a little pain involved that it's worth it and so if you can find somebody to help ease the skids grease the tracks and help you get into that nice and comfortably which is what my intent is on this channel for anybody who's pursuing CCNA that's a good thing and then you can basically understand the concepts and then you can appreciate more of the details and then if you want to become a most network engineers are not going to become programmers but understanding how the Python scripts are working and some of the tools that are used that be important so the answer is yes it's coming let me see what else do we have are you planning on creating content for CCNP so anything CCNP related on this channel is not going to happen it's CCNA exclusively on this channel as CVC Nuggets we've got Jeremy Network chalk Geoff Kish Knox Hutchinson and others who are working on the libraries for the CCNP stuff and that's a paid service there is a free trial if you want to check that out but those are in process and going and I'm saving all that CC and P level stuff for CBT Nuggets so who knows in two years maybe we'll make another channel for ccmp but once I wanna make sure the CCNA is all buttoned up and Jo is asking did I take the CCNA already know I had to have not taken the CCNA already I will network Chuck took it are heating up so a network chuck took the dev net I think on Monday he passed knock sessions to ticket and I thought okay okay I first of all I need to brush up on my network automation and program ability and then once I do that I'll look at the blueprint I'll do I'll give the same file take the same advice I've been giving and that is look at the blueprint go through each item ask myself on a scale of one to five how well do I know that if I'm a four or better I'll go take the exam there's something like I'm a two or a three I'll spend a few hours brushing up on those topics if there's a lab item that says configure I'll make sure that I know how to both configure and troubleshoot that technology there's not too many like that by the way and then go take the exam so I will be taking the exam but probably not 4mm unthe or two all right still going down the list okay Justin saying I found more free content do you want to add it to newer videos or the ones where you ask for support so I've got on the discord Channel I think that'd be a great place to collect all that and so some of the rules for the discord Channel are that any post that we do there's you know no harassment of any type and all those normal things but also no sharing of any any paid training content so no brain dump snow stealing other you know no content that's paid for somewhere else something like that but if you have free content just another let's go ahead and put it in discord and if there's not a channel yet for it just go ahead make a recommendation and I or one of the moderators can go ahead and make that channel and then that would be great and we'll name it something like additional free training and I maybe I make a special channel that's really don't mmm we'll figure out a great way to do it so it's easy to find on the discord server so the discard server I'm pretty impressed that's pretty amazing pretty good to communicate and Sufjan can we use the cisco arrow net 3700 AP connected to a home router to act as an AP if it if it supports i'm not familiar with that specific model off the top of my head but if it supports autonomous mode which is the AP does all the brains than thinking on itself yeah you could use it as an access point to do all the normal access point things if it doesn't support that if it's a if it supports lightweight only where it needs a controller then it wouldn't be too successful so it depends on if it supports autonomous mode if it does you can just image it as autonomous mode or said that and then use it I did that when I taught the Cisco CCNA Wireless which is no longer a test but when I taught that I had I used a virtual wireless LAN controller running on a computer and then in the physical world had two access point three access points and I demonstrated in that see that CBT Nuggets course I demonstrated how to change them back and forth to lightweight vs. autonomous autonomous basically meaning you don't need to use a controller to make it work all right Dan I don't know the ID I don't know the answer to that question so I OS on UNIX just to give you a heads up so if you purchase a license for viral yet you know you your license that product from Cisco it's 200 bucks a year I believe and I owe you which is the iOS on UNIX isn't officially licensed to any well they have Cisco has big partners that I think they give it to and allow them to use but for the average human iOS on UNIX is not a it's not a legal or lawful thing so for CCNA stick with packet tracer learn the commands and be well and safe okay let's see here what about a security channel that's a good question that's from ol Adeje a security channel might be good the CCNA channel is probably gonna take a few more months to fully baked and then once we have a lot of people who are benefitting from it and coming back I want all the Alumni to come back don't forget about us come back help other people catch a stream occasionally have some fun as you continue to progress in your ccnp I want you to outgrow this channel I want you to master this content and then just crush it and never stop that's it so come back occasionally and say hi so maybe after this channel is all like there's nothing else that can be taught there's no demo that can be done everything's been covered perhaps we'll look at a security Channel but there's no CCNA security anymore so the first security we're looking at is the core and concentration exams at the NP level so we shall see and Vai be hav thank you for the question which firewall certificate right after right should I get after the CCNA what I would do is if you are working in an organization or you think you might want to work in an organization where they're using a certain type of firewall so if you get a dice comm or in the state's monster.com it might be international as well find out what they're using at the place that you would like to work and then take a look at job requirements and what they want you to know about it and I would focus on the one you're most likely to use and if you've got a company it has a firewall maybe they have a SAS maybe start learning that or if they have firepower or if they have checkpoint or Palo Alto I would focus on using those because what happens is if you learn the technology for a product and then you never use it it evaporates after time and so just to memorize it for to have it in your head for like a half a year or six months or six months or a year it may not be as beneficial if you can never apply it so I would say go for the firewall that you're most likely to see or the one that you can get hands-on practice that's also a big thing if it's a like checkpoint they offer even from checkpoint if you get their CD I already download the image and as a CD image and you can actually install it and they have like a 15 day free trial which gives a person an opportunity to practice with it and you know run run it through its numbers where other vendors I'll leave them all nameless don't make it so easy so there's also that - how which technology could I do the hands-on practice with and which there's three proto there's three primary firewalls that are competing for the space Palo Alto checkpoint and Cisco's firepower so any one of those three would be good bets all right another question GRE tunnels Cisco - Cisco and perhaps GRE tunnels Cisco - cumulus juniper other and tuff of so if you would you know I think oh that's encore huh look at the encore blueprint yeah sure enough Giri an IPSec tunneling I don't know that that's on the CCNA blueprint so let's go ahead and put that in the discord server in the channel for other recommendations and once we run out of CCNA level content I would be happy to take a look at a few of those all right thanks for the request it's good to have you by the way it's good to have everyone here and I don't think CBT Nuggets has any micro tech training okay I think me answer the one on the channel for ccnp security probably not for a long time it's 1:30 a.m. says office too crazy I got to go to bed awesome thanks for being here I appreciate the sacrifice of staying up a little bit later or staying up early to be here it's great to have you and let me see if there's anything else can you explain the use of a null route and a good use for it Dena that's a great question let's go let me see if I have a live interface still and if we do I can actually demonstrate that and oh I've got three minutes yeah that's not gonna happen it says I have three minutes left on that lab is that I set a timer for two hours and I got three minutes left so if if we are doing summarization which we are going to cover in subnets Saturdays but summarization is where we're taking like 15 or 100 networks and we're advertising a summary route so let's do an example of let's do a gross example a gross over summary and let's say we have the following networks 10.1 16-bit mass 10.2 16-bit mass 10.3 10.4 10.5 tend out etc all the way up to 254 so we have all those 254 networks if we created one static route that said to get to network 10 dot anything like 10000 with a 20 with a 8 bit mask that one IP summary network address that one summary route is going to cover all the rest so what we could do is if we advertise that route we could create a null rau when we obtained it we could create a route saying IP route to get to 10000 xx an 8-bit mask the next hop is null 0 that would be a route to null 0 it doesn't really exist and then we could suppress all the other routes from being advertised so we're basically telling the rest of the network 10 anything 10 anything over here and once those packets come in then the detailed routes that we have we can actually use and forward the package to the specific networks but at the same time if we get a packet for 10 dot let's say we didn't have a real Network for 10.28 didn't exist if we get a packet for 10.28 because they're coming our way because we did the summary the 10 summary route to null 0 is gonna take that 10 because it doesn't match anything else in the routing table more explicitly and it just kills it right there so instead of trying to route a packet that doesn't belong that doesn't have a destination that we have reachable we can just drop it so anytime we need to do a summary or not anytime but doing a summary with a null route is one example of when we would use one just to catch any stray routes that come in any straight packets and send them to the bit bucket so null 0 is like the bit bucket that is a null route and a good use for it thanks for the question do you know office - crazy okay thank you and trust the pop process thank you for your help and in the channel as well as everybody who's answering questions and I think that's it I think that's it for today's live stream next Saturday which is just a few days away we're gonna be taking a look at subnet Saturday and advancing on what we covered previously which will also help reinforce some of the work we did today regarding those four routes and identifying the ranges for those networks which would determine which would be the longest match in the routing table which we had to do manually but that was really an exercise and identifying subnets in the routing table and awesome awesome feedback all right so off so office too crazy just to confirm that my focus here is gonna be CCNA 200 301 and that blueprint and all things on it alright Oh Rome it's asking can no routes is that possible in the a si I don't know let's find out let me Google that let me google that for you it's possible on a Cisco router let me go over here and let me bring up a browser and I'll sleeve the camera right there if that's okay and let me bring this up okay new window went on the wrong screen and Cisco a si no route hmm alright so let me share my screen now that I have it up and boom here we go so based on this extensive Google search that I did solved a si nil route question Cisco community solves hello it looks like there are no null route function in earlier versions of a si just checking today when checking nine dot X it will have an old route now we're mmm-hmm how old is that 50 to take a look at that note so that's what I would do I just go I just look it up well that's from 2014 Oh use the tion instead hmm IP route mm-hmm I'm not getting the answer I wanted from this let's do uh let's do that search again a sa cuz they want a current version so this talks about null routes but it's not regarding a essay this is its approximation that's a great question so I don't know the answer to that what I would do is I would take the version of a essay that I currently have and I would just go to the online doc and look it up because it looks like it may depend on the version and it definitely appears that some of the older versions don't support null 0 null routes on the a essay alright hey thanks everybody for joining the live stream is so good to have you here if you're studying for CCNA we want you to be here if you've already got your CCNA we want you to come back here and help others join the discord server the link will be posted below and if you haven't already subscribed please feel free to do so if you enjoyed parts of the video click on the like if you didn't like the video my name is todd lammle just kidding I've only met Todd was and he seems like a really good guy alright this is the joke and then I will child leave the stream running with little music and I'll answer that last chat directly for the chat message hey thanks everybody I'll see you in the next live stream bye wait [Music] [Music] walking on [Music] [Music] [Music] [Music] by side by side [Music] [Music] [Music] [Music] [Music] [Music] [Music] walking on [Music] [Music] [Music] [Music] crowd by side right boys [Music] [Music]

Channel: Keith Barker

Views: 9,277

Rating: 4.9426522 out of 5

Keywords: 200-301, 200-301 ccna, 200-301 cisco, 200-301 vs 200-125, 200-301 videos, 200-301 exam, 200-301 ccna certification, 200-301 study, cisco, ccna, networking, cisco ccna 200-301, cisco ccna training, router, routing, routing table, routing table in computer networks, routing table example, routing table basics, administrative distance, administrative distance in networking, administrative distance in routing, administrative distance vs metric, administrative distance cisco

Id: qU2qFU7NgNU

Length: 106min 51sec (6411 seconds)

Published: Wed Feb 26 2020