Serial Countersign Routing Made Easy

Serial countersign routing

welcome in this video we are talking about understanding the routing table here's an example of what the writing table would look like if you did a show ip route on a cisco ios device so we need to understand what the sources are what the numbers are what the bracket means what the via means numbering the timing all of that because this structure allows us to decode how the router will make its path determination or its path selection so here we have how the routes are sourced this will identify how the network was learned by the router this will be directly connected interfaces have two route sources c identified directly connected directly connected networks are automatically created whenever an interface is configured with an ip address while l is identified that is a local route local routes are automatically created whenever an interface is configured with an ip address and active so similar but slightly different scene is always going to be there if they're directly connected and have an ip address l is local route has to have an ip address and is active the next group is going to be the destination you'll notice that the destination of the remote network and how that remote network is connected you'll see that there is a ip address subnet and how it is connected next will be the outgoing interface identifying the interface on the router connected to the destination network this is going to be what interface do i send it to be able to reach that network another example is going to be a little more structured example r is going to be the route source again r is going to be decoded a little bit later here we have the destination network r is how the route was learned destination network administrative distance will be the 20 the metric or the measurement will be 2 where we're sending it might be an ip address or a interface route time is going to be when the route was last heard from and lastly will be the outgoing interface so depending on how this route is set up you may see the next hop and an outgoing interface you may see one or the other so here is the example that cisco gives for both ipv4 and ipv6 again here you'll notice how it's learned the destination network the administrative distance the metric again this identifies the value assigned to reach the remote network lower the value the better this will be the next top this identifies the ip address of the next router time stamp when it was last connected and the exit interface if we're talking ipv6 same general setup except you're going to notice ipv6 address but it will have the same seven items so let's look at one route source they are going to be different measures so it's either going to be directly connected static or dynamic routing if it's directly connected that's going to be either l or c if it's going to be a static route it should typically be denoted as s if it is a dynamically learned route it will be o or a different letter kind of depending on which routing protocol o means it's using osbf as the routing protocol s is static so as long as it's not lc or s you should be fine star will denote a default route as well so we talked that we talked about administrative distance also called a d a d is actually just a clever way of saying trustworthiness the lower the ad the more trustworthy the route because routers will update periodically you have to understand how much trust do you have in that route to actually be able to go from route a b c and the paths in between the ad kind of finds that trustworthy in this there are predefined trustworthiness values or 80 values that you should know you should understand that if we are talking a a d value of 110 that's going to be ospf if we know we're talking uh an ad measure of 90 that'll be eigrp on the cisco exam they will expect you to know the 80 values and again the lower the value the better this is understanding the routing table in a nutshell if you have any questions just let me know thank you