1 00:00:00,720 --> 00:00:07,980 About five minutes ago and it executed three times so let's enable always be a fun ride and see how 2 00:00:07,980 --> 00:00:09,770 the output changes. 3 00:00:09,950 --> 00:00:17,220 So not to show the interface brief will allow me to see the interfaces configured on this router and 4 00:00:17,420 --> 00:00:25,230 as you can see here in 1:59 has been configured on several ones like Sarah and 10 1 3 1 has been configured 5 00:00:25,470 --> 00:00:33,720 on serial 1 slash one that's configure a loopback on the Sharada interface back to zero IP address 6 00:00:38,630 --> 00:00:45,890 and it's configured as portable to tapping the command Rodda OSPF to will enable OSPF on this router 7 00:00:45,920 --> 00:00:47,490 with Prozess ID. 8 00:00:47,870 --> 00:00:53,940 And in this case lets enable OSPF using this format 9 00:00:56,860 --> 00:01:05,760 Savi same she said just enable OSPF on all interfaces and lets put those interfaces in areas Zerah as 10 00:01:05,760 --> 00:01:06,980 you can see here. 11 00:01:07,290 --> 00:01:16,410 A neighbor relationship or adjacency is being formed maybe 10 1 5 1 on serial 1 slash 0 has gone from 12 00:01:16,410 --> 00:01:24,210 the loading state to the full state the full state means that the rod is exchanging links that updates 13 00:01:24,300 --> 00:01:25,860 with one another. 14 00:01:25,890 --> 00:01:36,300 This can get confusing maybe 10 1 5 1 is not directly connected to us IP address 10 1 5 1 is not directly 15 00:01:36,300 --> 00:01:38,260 connected to router 2. 16 00:01:38,560 --> 00:01:47,370 However that IP address is the Rodda ID of router 1 and routed to has formed the neighbor relationship 17 00:01:47,370 --> 00:01:56,490 with Rotto one and thus the Rodda ID ferrata one is shown in the output not the IP address of serial 18 00:01:56,490 --> 00:02:03,360 one selects Zira by the same token on Router one notice a neighbor relationship has been formed with 19 00:02:03,360 --> 00:02:12,890 quadruple to on serial once Zerah notice that the process id Arado one is one whereas the process id 20 00:02:12,890 --> 00:02:21,440 on Rodek t is t process IDs are local to the rodders and do not have to be the same. 21 00:02:21,530 --> 00:02:27,900 So I Can Talk To Come on show IP OSPF interface and you can see that OSPF has enabled them a loopback 22 00:02:27,900 --> 00:02:28,820 interface. 23 00:02:28,940 --> 00:02:36,860 Serial 1 slash one interface serial 1 selection zero interface which are the three interfaces configured 24 00:02:36,860 --> 00:02:37,990 on route. 25 00:02:38,570 --> 00:02:46,420 Going back to Route 1 and topping the come on show IP OSPF will allow me to see that the SPF algorithm 26 00:02:46,420 --> 00:02:52,160 has now been executed five times because new rods have been added to the topology. 27 00:02:52,570 --> 00:03:02,910 Show IP OSPF neighbor will allow me to see my OSPF neighbors Rato one at the moment only has a neighbor 28 00:03:02,910 --> 00:03:09,710 relationship with Rodda to notice the relationship is full notice the dash. 29 00:03:09,870 --> 00:03:14,770 The dash means that no election has taken place on this interface. 30 00:03:15,000 --> 00:03:21,360 And the reason why is that its a point to point link on a fast ethernet network you would see various 31 00:03:21,360 --> 00:03:29,650 states share like Diyar with designated Rodda BTR for backup designated Rodda and D or other. 32 00:03:29,730 --> 00:03:34,370 In other words the neighbor is neither a DVR or a BT. 33 00:03:34,520 --> 00:03:41,570 It's important to realize this C'mon show be OSPF neighbor is giving me information about my neighbor 34 00:03:41,600 --> 00:03:44,430 Rodda not about me. 35 00:03:44,430 --> 00:03:50,760 In other words neighbor with IP address quadruple two is connected to our local cereal once there is 36 00:03:50,760 --> 00:04:00,870 zero interface and the neighbor's IP address on that interface is 10:01 to be on router 2 show IP OSPF 37 00:04:00,870 --> 00:04:08,700 neighbor will allow me to see similar information from out of one notice Rotto ones neighbor ID is 10 38 00:04:08,700 --> 00:04:10,320 1 5 1 now. 39 00:04:10,360 --> 00:04:17,060 As per best practice we should be using a loopback for the Rodda Id rather than a physical interface. 40 00:04:17,190 --> 00:04:20,820 So in Router one lets create a loopback interface 41 00:04:28,150 --> 00:04:37,750 ON-TOPIC come on do show IP OSPF interface and you'll notice that the router ID has remained the same. 42 00:04:37,750 --> 00:04:45,920 You'll also notice that the loopback interface is not in the list of interfaces and the reason for that 43 00:04:46,250 --> 00:04:52,550 is that we only enabled OSPF on specific interfaces so topping that come on do show. 44 00:04:52,730 --> 00:05:03,460 Run pipe section OSPF will allow me to see the configuration of OSPF in the running configuration. 45 00:05:03,640 --> 00:05:09,750 And as you can see here OSPF has not been enabled on the loopback interface. 46 00:05:09,910 --> 00:05:18,440 So let's talk rodder OSPF one network and let's specify a loopback address. 47 00:05:19,410 --> 00:05:30,920 Now topping to come on do show ID OSPF interface shows me that Mahratta ID is still 10 1 5 1. 48 00:05:31,080 --> 00:05:40,330 Let's talk this game on clear IP OSPF process and say yes to clear all OSPF processes. 49 00:05:41,070 --> 00:05:48,630 As you can see the neighbor relationship went down and then reestablished Choe IP OSPF interface to 50 00:05:48,630 --> 00:05:56,410 show me that the Rodda ID is still 10 1 5 1 now could remove OSPF and re-enable it. 51 00:05:56,440 --> 00:06:00,330 That's a bit of a blunt instrument to change the route ID. 52 00:06:00,610 --> 00:06:10,100 So I'm going to go Confiteor Rodda OSPF one router ID and then specify the Rodda ID is quite Ripl one. 53 00:06:10,420 --> 00:06:17,860 And notice what the router says either reload or use the clear IP OSPF Prozess c'mon for this to take 54 00:06:17,860 --> 00:06:18,790 effect. 55 00:06:19,230 --> 00:06:29,780 So they'd stop clear IP OSPF process say yes to all processes and see what happens. 56 00:06:30,570 --> 00:06:37,280 Once again the neighbor relationship went down and reestablished topping to come on show IP OSPF interface 57 00:06:37,950 --> 00:06:47,730 shows me that the Rodda ID is now set to quadruple one on router to show ID always V.F. neighbor noticed 58 00:06:47,770 --> 00:06:55,120 the neighbor relationship has changed to use the loopback address of quadrupole one that lets enable 59 00:06:55,190 --> 00:07:00,240 always get router three to ensure full connectivity between all subnets 60 00:07:03,140 --> 00:07:07,340 show IP interface brief will allow me to see the interfaces configured on the serrata.