CCNA 2 Module 15 Part 1 Static Routing

in this video i'll review module 15 which is static routing so we will look at static routes how static routes work in comparison to dynamic routes also how to configure ip static routes default static routes floating static routes and we will look at how to configure both of those in both ipv4 and version 6. so there are various types of static routes if you remember from module 14 we looked at how to configure a router and then the differences between dynamic and static routes with dynamic routes we learn that the router determines the path for data however in static routes someone else usually the network administrator would configure that into the router so that would appear in the routing table for the router when you issued the show ip route command you would see the routes that the router has learned that could be dynamic or static static routes can be configured for both ipv4 and version 6. there are standard static routes so we'll look at that first we'll look at default static routes floating static routes and summary static routes typically when you configure a static route the syntax would be iprout done at your privilege mode prompt the ip route the destination network its mask and then either the exit interface or the next top address the difference between the ways that the address is specified is that the next top route would be the route that the data needs to take as it goes to the next device that would be your next top so if you're an r1 you're configuring a static route to reach a network beyond r2 then you would the data would have to travel to r2 so the next top address would be the incoming interface on r2 now directly connected static route if you're configuring for the connected interface then you use the exit interface on r1 for example if it's a fully specified static route you would list both the exit interface on that router plus the next top address of the next device so it would be if r1 and r2 for example you're configuring r1 you would list the exit interface and then the incoming interface or ingress interface on r2 again this is your syntax so config t then ip route the destination network its subnet mask and then either the next top address or the exit interface if configuring ipv6 you would use the same syntax but remember that you don't have a subnet mask when you're configuring an ipv6 address so you would use the slash notation or prefix link so instead of iprout it would be ipv6 route the destination network with a slash notation and then either the exit interface or the next hop address it is possible to configure static routes for both ipv4 and ip version 6. you can configure ip addresses for both ip version 4 and ip version 6. you can configure static routes for both so you can use those dual you can do that because i p version 4 talks to i other ip version 4 addresses same thing with version 6. so version 6 is going to communicate with other version six devices they don't cross over so you can put both on the devices now if you're actually looking at a configuration so i p version 4 routing table if you see the c's and the l's the c's indicate the network that was used so i'm going to go back up here so for r1 r2 and r3 if you're doing your basic configuration so no static routes have been configured we see that listed here no static routes are configured for either version 4 version 6. so what's been done is in r1 they've done the basic device configuration where they configured g000 with the correct address which would be the 172 16 3.1 this interface has been configured for r2 the s010 has been configured g00 and s011 for r3 these two interfaces have been configured you would see those indicated with a cnl if you're looking at r1 the interface address is actually 17216 2.1 it's connected to network 2.0 so if you were looking at that that would be this particular interface here it's 2.1 that would be the l the c would be the network it's connected to so because you have an interface on this network it it does make that as one of your connected networks okay and that's how it would work throughout the entire network so if you were to look at r2 you would see the same thing you would see lots of c's and lots of l's these are just the interfaces that are configured during your basic configuration same thing with r3 in this case r1 can ping r2 but r1 cannot ping r3 why is that the case well r1 can ping r2 it knows about this network because it has a device connected to it but it doesn't know about the far-reaching networks so i'm going to go back to r1's routing table so r1 knows about the 2.0 network in the 3.0 network okay so 172 16 2.0 172 16 3.0 it doesn't know about this network this one or this one okay so there's one two three four five networks yet if we look at the c's we only see two networks so going back to module 14 in this curriculum which was the last section on configuring routers routing concepts i believe now just because one router knows about a path or a particular set of networks it doesn't mean that other routers know about it okay so that's one of the rules and you have to go through and look at the routing table for every single router okay so just because one router knows about the path doesn't mean another one does just because a router knows how to reach a destination doesn't mean it knows how to return also if you have five networks in your topology you should see all five networks listed if you do not then that device will not know how to reach all the devices within the topology so again think about a router's gps so if you're trying to get from point a to point b and some of the routes are not listed you're going to have some missing links you're not going to be able to actually get there you might travel a lot longer direction you're just not going to probably not know how to find the address that you're looking for so this is the same way with a router okay each router needs to know about all of the networks within the topology so again if there are five networks in the topology then r1 needs to have knowledge of five networks r2 does and so does r3 right now they do not but that would change after entering in static routes same way with ipv6 so we have the two networks that we know about for r1 same with r2 we know about three networks and then the same thing with r3 so r1 can ping r2 because it knows about that one but it doesn't know how to reach this far destination just like with version 6. so that really doesn't change between version four and version six in the way they need to know the knowledge of the network and how how they reach those networks and how they build their routing tables that all stays the same so if you are looking at the output for r1 r1 knows about this network 172 16 3.0 and 172 16 2 2.0 so they're configuring r1 with static routes to the three remote networks which would mean it would be the 17216 1.0 192 168 1.0 and 192 168 2.0 so this is the correct syntax you would type iprout again at your privilege mode prompt so ip route 17216 1.0 that would be the first one here its mask is 255 255 255.0 you can see that because of the slash 24 listed now we're using a next top address so if data is leaving r1 to reach this network it has to go to this interface on r2 in order to reach it that's the next logical interface that it would need to go to so with 192 168 1.0 being over here data would also have to leave r1 and travel to r2 so that would also be the next top address and same with 192.168.2.0 because the topology that data would also have to travel from r1 to r2 and again that would be the next top address if you put in all three of those then you will see entries that look like this they will have an s and s indicates a static route and you will see those entries appear so just for review when you're looking at a routing table you would see how you learned about the route which would be the s the network this is the administrative distance the administrative distance is the trustworthiness of a route the lower the number the more trustworthy it is so if it's on a directly connected interface such as this one down here that's on that device it says directly connected it's actually not listed but the administrative distance for a directly connected device would be zero you can't get more trustworthy than on the device itself static routes are next in terms of how trustworthy they are the administrative distance is one and it's zero hops away that's the metric so it's just the next device so it doesn't have to travel any further if you had to pass through three routers to get there then the metric would be three this is the next top address so you get here by going here that's the same way it would read for the other two static entries with ipv6 before you can type in the addresses or the static routes you would have to type in the command ipv6 unicast routing once you type that in you can type in the static routes and again the syntax is ipv6 route instead of ip route the destination network you're using the slash notation because you're using ip version 6 and then the next hop address and when you do that you'll see the route appear with the s just like you did in ip version four okay you'll see the administrative distance you'll see the metric and then you will see the next top another option is to use the exit interface instead of the next top address if you were to do that you're looking at r1 and trying to type in the static route entry or 1.0 the 17216 1.0 you would still use the destination network the mask but you would use the exiting interface on that particular device so s 0 1 0. it's not the address notice it is the actual interface now what are the advantages and disadvantages to doing that well there's a couple of advantages and disadvantages note here in this area they tell you the next top address is generally recommended and only recommend using directly connected static routes for point-to-point serial interfaces so what you'll see is the next hop address so why would you use a directly connected interface well here's the advantage to using a directly connected interface it prevents something called recursive lookup so if you remember from the previous part of this curriculum or maybe ccna1 that the routing table is going to try to match the longest match in each one of these routing table entries so it's going to go line by line using the destination address and then choose each one of these networks take everything in binary and try to find the longest match to find the best match for that particular destination when it does that so it would determine then well what interface do i need to use in order to get to the 2.0 network so it would need to match up everything in the routing table then determine what exit interface to use in order to reach that if you use the directly connected interface it prevents the router from having to do that so it doesn't have to go through all that it just says go this way so it prevents what we call the recursive lookup of having to figure all that out so i'm still not quite sure on why cisco would always recommend using that next hop address it seems like it would be more efficient to use exit interface but that is what is taught in the cisco academy curriculum and it's stated that that's preferred so we follow those guidelines but as a side note i personally kind of wonder why it wouldn't just be more useful to use the exit interface okay so ipv6 directly connected to static routes are configured the same way as version four so ipv6 route the destination network and then again the interface exit interface if you wanted to specify everything you would use the fully specified static route which would indicate both here's what it would look like ip route 17216 1.0 with the mask and then the exit interface and you can abbreviate all this you don't have to write it all out so you could do the g001 okay so the exit interface and then the next top and you can do that with both version 4 and version 6. to verify static route you can issue the command show ip route static show ip route network show run and you can use the pipeline if you want for section and just showing you iprout it is not wrong if you just wanted to type show run this is for ipv4 if you wanted to replace the ip with ipv6 you could check your ipv6 routes so here's examples of a show command so show iprout static so you're looking just the static entries only if you want to look at a specific route you could do that show iprout so just for 192.168.2.1 you could display the ipv4 static route information only here do the same thing with version 6. at ipv6 static routes if you're looking at a specific network you can list that like you did with version four and then you could use the pipeline here with your show run command to look specifically for ibv6 route information so this is the first part of module 15 on your different types of static routes and looking at the routing table hopefully this will give you a little bit better understanding of how to configure a static route and how to find that information and view it in your routing table

Channel: Shelley Allen

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Id: Q_p07Vj5TaY

Length: 19min 41sec (1181 seconds)

Published: Tue Apr 13 2021