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These are the user uploaded subtitles that are being translated: 1 00:00:00,000 --> 00:00:03,000 align:middle line:84% To enable connectivity in this network 2 00:00:03,000 --> 00:00:05,000 align:middle line:84% we can configure static routes 3 00:00:05,000 --> 00:00:09,000 align:middle line:84% so on router 1, as an example, conf t ip route 4 00:00:09,000 --> 00:00:17,000 align:middle line:84% and notice we have various options, destination prefix, profile, static and VRF 5 00:00:17,000 --> 00:00:22,000 align:middle line:84% it’s important that you know the options for static route. 6 00:00:22,000 --> 00:00:27,000 align:middle line:84% so as an example, the destination prefix 7 00:00:27,000 --> 00:00:32,000 align:middle line:84% or destination network that I want to configure is 10.1.2.0 8 00:00:32,000 --> 00:00:35,000 align:middle line:84% and the reason that I want to use 10.1.2.0 9 00:00:35,000 --> 00:00:38,000 align:middle line:84% is because this is a /24 network. 10 00:00:38,000 --> 00:00:42,000 align:middle line:84% Now you can implement summarization of your static routes 11 00:00:42,000 --> 00:00:49,000 align:middle line:84% but for now use the exact mask, question mark is destination prefix mask. 12 00:00:49,000 --> 00:00:57,000 align:middle line:84% so 255.255.255.0 because this is a /24 question mark 13 00:00:57,000 --> 00:01:04,000 align:middle line:84% I can now specify the next hop router or an outgoing interface 14 00:01:04,000 --> 00:01:08,000 align:middle line:84% when setting up routing look at it from routers point of view. 15 00:01:08,000 --> 00:01:12,000 align:middle line:84% From router's 1 point of view, what is the next hop IP address 16 00:01:12,000 --> 00:01:15,000 align:middle line:84% that he uses to get to this network? 17 00:01:15,000 --> 00:01:19,000 align:middle line:84% In other words, when router 1 sends traffic out of this interface 18 00:01:19,000 --> 00:01:22,000 align:middle line:84% what’s the next IP address that it's going to hit? 19 00:01:22,000 --> 00:01:25,000 align:middle line:84% it's going be this IP address 10.1.1.2 20 00:01:25,000 --> 00:01:29,000 align:middle line:84% So if router 1 was trying to get to a network somewhere on the right here 21 00:01:29,000 --> 00:01:33,000 align:middle line:84% the next hop would still be 10.1.1.2 22 00:01:33,000 --> 00:01:38,000 align:middle line:84% because that’s the next hop IP address that the router is forwarding traffic to. 23 00:01:38,000 --> 00:01:42,000 align:middle line:84% So just think what’s the next IP address that going to be hit 24 00:01:42,000 --> 00:01:45,000 align:middle line:84% when the router forwards the traffic out of an interface 25 00:01:45,000 --> 00:01:47,000 align:middle line:84% that’s your next hop IP address. 26 00:01:47,000 --> 00:01:54,000 align:middle line:84% So, in this case, it's 10.1.1.2 we can specify various options here 27 00:01:54,000 --> 00:01:57,000 align:middle line:84% such as an administrative distance make the route permanent 28 00:01:57,000 --> 00:02:01,000 align:middle line:84% and other options but for now that’s all I’m going to specify. 29 00:02:01,000 --> 00:02:04,000 align:middle line:84% Notice we’ve got the option carriage return 30 00:02:04,000 --> 00:02:06,000 align:middle line:84% and that’s what we’ve used now 31 00:02:06,000 --> 00:02:08,000 align:middle line:84% in other words, routes has been added to the routing table. 32 00:02:08,000 --> 00:02:12,000 align:middle line:84% Let’s confirm that so sh ip route 33 00:02:12,000 --> 00:02:18,000 align:middle line:84% shows us that this network 10.1.2.0 34 00:02:18,000 --> 00:02:22,000 align:middle line:84% has been added to the routing table as a static route. 35 00:02:22,000 --> 00:02:31,000 align:middle line:84% S means static, route is available via 10.1.1.2 36 00:02:31,000 --> 00:02:33,000 align:middle line:84% in other words, this IP address. 37 00:02:33,000 --> 00:02:46,000 align:middle line:84% So can we ping 10.1.2.2? Ping 10.1.2.2 pings failed 38 00:02:46,000 --> 00:02:49,000 align:middle line:84% but we are getting output on router 3 39 00:02:49,000 --> 00:02:55,000 align:middle line:84% so on router 3, it’s sending an echo reply back 40 00:02:55,000 --> 00:03:02,000 align:middle line:84% from 10.1.2.2 to destination 10.1.1.1 41 00:03:02,000 --> 00:03:05,000 align:middle line:84% so in other words, the traffic is getting from router 1 to router 3 42 00:03:05,000 --> 00:03:08,000 align:middle line:84% but it’s not getting back again. 43 00:03:08,000 --> 00:03:17,000 align:middle line:84% And the reason for that is router 3 doesn’t have a route back to router 1. 44 00:03:17,000 --> 00:03:20,000 align:middle line:84% We can see that by using the command sh ip route 45 00:03:20,000 --> 00:03:29,000 align:middle line:84% back to 10.1.1.0. as an example, if I try and ping 10.1.1.1 46 00:03:29,000 --> 00:03:33,000 align:middle line:84% the IP address of this router, router 1 47 00:03:33,000 --> 00:03:37,000 align:middle line:84% in network 10.1.1.0/24 pings failed 48 00:03:37,000 --> 00:03:40,000 align:middle line:84% and we can use the command debug ip packet 49 00:03:40,000 --> 00:03:48,000 align:middle line:84% to show us that the router doesn’t know how to get to that network. 50 00:03:48,000 --> 00:03:52,000 align:middle line:84% The traffic is unroutable. 51 00:03:52,000 --> 00:04:00,000 align:middle line:84% So how do we fix this? Well, we need to create a static route back again. 52 00:04:00,000 --> 00:04:05,000 align:middle line:84% So IP route 10.1.1.0 with the mask /24 53 00:04:05,000 --> 00:04:12,000 align:middle line:84% and in this case we're going to use the next hop IP address 10.1.2.1 54 00:04:12,000 --> 00:04:16,000 align:middle line:84% now you can use the local outgoing interface 55 00:04:16,000 --> 00:04:20,000 align:middle line:84% but that’s not recommended on Ethernet interfaces 56 00:04:20,000 --> 00:04:27,000 align:middle line:84% only do that on point to point links such as serial interfaces on Ethernet 57 00:04:27,000 --> 00:04:31,000 align:middle line:84% use a next hop IP address not the local outgoing interface 58 00:04:31,000 --> 00:04:34,000 align:middle line:84% so does the ping work now? 59 00:04:34,000 --> 00:04:38,000 align:middle line:84% Yes it does and you can see a lot of output 60 00:04:38,000 --> 00:04:40,000 align:middle line:84% so let’s turn off debugging 61 00:04:40,000 --> 00:04:44,000 align:middle line:84% un all or undebug all turns off debugging 62 00:04:44,000 --> 00:04:47,000 align:middle line:84% I’ll only enable ICMP 63 00:04:47,000 --> 00:04:49,000 align:middle line:84% so debug ip icmp 64 00:04:49,000 --> 00:04:55,000 align:middle line:84% we can see the echo replies are sent and the pings succeed 65 00:04:55,000 --> 00:05:00,000 align:middle line:84% in other words, the traffic got from router 1 to router 3 and arrive back again. 7468