1 00:00:07,720 --> 00:00:15,610 This is one of multiple videos discussing the wispy FDR and video designated Rada and become the designated 2 00:00:15,610 --> 00:00:16,070 Rada. 3 00:00:16,240 --> 00:00:24,850 Elections and selection criteria on Cisco we have this document that says that dealers and BDO elections 4 00:00:24,850 --> 00:00:33,340 are done via the hello protocol Hello packets are exchanged via multicast packets on each segment. 5 00:00:33,340 --> 00:00:39,420 The Rada with the highest priority on the segment will become the D.R. for that segment. 6 00:00:39,430 --> 00:00:43,380 The process is repeated for the PDR in the case of a tie. 7 00:00:43,420 --> 00:00:51,110 The Rada with the highest Rada idea will win the default property on an interface is one if you set 8 00:00:51,250 --> 00:00:52,860 the primary to a zero. 9 00:00:53,050 --> 00:00:58,440 It means the Rada will not become a ADR or a PDR. 10 00:00:58,470 --> 00:01:04,230 Remember that the D.R. and BDO concepts are per multi access segment. 11 00:01:04,230 --> 00:01:10,860 Setting the OSP of priority on an interface can be done using the IPO SPF Prodi command. 12 00:01:10,860 --> 00:01:19,210 Now let's look at the segment that has rather 3 rather 2 to 1 and read a full connected to it on the 13 00:01:19,210 --> 00:01:30,380 segment rudder one has neighbor relationships to rudder to rudder three and wrote a full note to the 14 00:01:30,380 --> 00:01:39,710 interface gigabit zero the stop entry is for the segment on gigabit 0 1 but we are concentrating on 15 00:01:39,710 --> 00:01:51,560 gigabit to 0 0 for the moment so we don't see a D.R. show IP or SPF interface brief what we do see is 16 00:01:51,560 --> 00:01:56,120 that the local Rata a one is the designated Rata. 17 00:01:56,150 --> 00:02:03,320 Now that goes against what we've just read the runner idea of this strata is lower than the other Rod 18 00:02:03,320 --> 00:02:09,090 is on the segment and this is where real world comes into play versus theory. 19 00:02:09,160 --> 00:02:16,720 The reason why Russia won was elected as the designated Rada is that in the previous video I configured 20 00:02:16,720 --> 00:02:20,340 Rada 1 first before I configured the other. 21 00:02:20,710 --> 00:02:26,720 So Rada 1 was the only Rada on the segment it was waiting for other. 22 00:02:26,850 --> 00:02:32,850 None appeared so it became the D.R. when the other rods were added to the segment and I added them in 23 00:02:32,850 --> 00:02:40,950 the order of Robert to then Rada a three then Rada for RADA one was already the designated Rada once 24 00:02:40,950 --> 00:02:46,290 a designated Rod is elected and a Roddick comes on to the segment with a higher priority will higher 25 00:02:46,290 --> 00:02:55,530 Rod I.D. It's not going to usurp or pre-empt the designated Rada the designated Rada remains the designated 26 00:02:55,530 --> 00:03:04,560 Rada and hence the local Rada with a lower rate I.D. which we can see by using the command show IP was 27 00:03:04,770 --> 00:03:05,430 interface 28 00:03:09,740 --> 00:03:23,230 is elected as the D.R. on gigabit 00 because it came on line first notice it has an adjacency or neighbor 29 00:03:23,230 --> 00:03:28,920 relationship with three routers brought it to is the backup designator Rada wrote a three and root a 30 00:03:28,920 --> 00:03:41,660 four R D or others show IP SPF and neighbor Rod it to is a PDR a 3 wrote a 4 or D or others on gigabit 31 00:03:41,720 --> 00:03:51,950 00 so what happens if we go on to gigabit 00 and we top IPO SPF priority 0 32 00:03:54,550 --> 00:04:10,560 show IP SPF interface what you'll notice is the a state on gigabit 00 has changed to D or other it's 33 00:04:10,560 --> 00:04:19,430 now formed a full relationship to rather to show IP SPF neighbor rather one has a full relationship 34 00:04:19,460 --> 00:04:23,370 to brought broader two as well as Rod four. 35 00:04:23,600 --> 00:04:32,940 The reason why Rod it too became the D.R. is it was already the BTR and then out of Rod it 3 and Rod 36 00:04:32,940 --> 00:04:41,810 of 4 Rod of 4 became to the BTR because it had a higher Rod I.D. So the theory is as follows. 37 00:04:41,850 --> 00:04:48,660 Rod it with the highest property becomes designated rata on a segment that's not entirely true. 38 00:04:48,720 --> 00:04:55,520 If one Rodda comes into the segment first before other Rod is that Radha will be the designated Rod. 39 00:04:55,980 --> 00:05:03,030 But if that all come online at the same time it's based on highest priority then highest Rod I.D. then 40 00:05:03,030 --> 00:05:08,890 highest loop back interface ip address then highest configured physical interface address. 41 00:05:09,300 --> 00:05:15,870 And in this case Rod a fool became the backup designated rider because it had the highest IP address. 42 00:05:15,870 --> 00:05:23,130 So what are going to do now is reboot the switch so that you can see the full process of how the exam 43 00:05:24,060 --> 00:05:35,820 explains how ideas are elected so first thing I'll do is change the protein of rod to 1 back to 1 on 44 00:05:35,840 --> 00:05:47,710 Rod a 2 to let's confirm the relationships show IP SPF neighbor Rod a 1 is a D or other Rod a 3 is a 45 00:05:47,710 --> 00:05:58,250 D or other Rod a 4 is a backup designated Rata and the local Rata is a designated Rata in the output 46 00:05:58,250 --> 00:06:06,510 show we can see there are of 4 is the backup designated Rada wrote a 3 and Rod a 1 or D or others. 47 00:06:06,510 --> 00:06:18,980 So let's see what happens when we shut down interfaces on the switch so shut down a range of interfaces 48 00:06:19,430 --> 00:06:23,800 gigabit 0 2 3 so shut those interfaces down. 49 00:06:25,090 --> 00:06:32,560 On router 1 show IP 0 SPF neighbor not may take it a while ingenious 3 to realize that the interfaces 50 00:06:32,560 --> 00:06:34,060 have gone down. 51 00:06:34,240 --> 00:06:41,590 So what I'm gonna do at this point is pause the video and what we should see is that these states change 52 00:06:42,770 --> 00:06:48,080 so after a while the dead timer expires for the neighbor relationships. 53 00:06:48,210 --> 00:06:56,140 Previously we had these neighbor relationships and now those neighbor relationships have disappeared. 54 00:06:56,140 --> 00:07:02,830 The only neighbor relationship that to one has is to rot for using this Ethernet link 55 00:07:05,680 --> 00:07:10,270 so to ensure that it doesn't get confusing I'll shut that link down as well. 56 00:07:10,270 --> 00:07:15,380 So we have no always P.F. neighbor relationships on route one at all. 57 00:07:16,350 --> 00:07:19,560 The switch has all of its interfaces shut down once again. 58 00:07:19,740 --> 00:07:20,730 So let's have a look. 59 00:07:20,730 --> 00:07:28,770 On rudder to show IPO SPF neighbor no neighbor relationships and write it to write a three show IPO 60 00:07:28,790 --> 00:07:34,350 SPF neighbor no neighbor relationships a for show IPO SPF neighbor. 61 00:07:34,550 --> 00:07:42,080 It only has a neighbor relationship on the surreal interface not on the Ethernet interface Serato for 62 00:07:42,110 --> 00:07:50,390 has a neighbor relationship to rot a five but no other neighbor relationships so on the switch no shut 63 00:07:52,650 --> 00:08:02,940 we've enabled all the interfaces on the switch so in a one off to a period of time we should see that 64 00:08:02,940 --> 00:08:04,920 neighbor relationships are formed. 65 00:08:05,070 --> 00:08:08,880 We can do a ping to check if the interfaces have come up 66 00:08:15,110 --> 00:08:20,240 interfaces are starting to come up on the switch pings are now succeeding. 67 00:08:21,180 --> 00:08:28,850 And now we see maybe relationships three neighbor relationships have been formed on a once a show IP 68 00:08:29,410 --> 00:08:39,200 SPF neighbor brought one has a two way relationship to rot it to rot a fool has become the designated 69 00:08:39,200 --> 00:08:44,550 Rada and a three has become the backup designated Rada. 70 00:08:44,870 --> 00:08:52,940 The reason why Rada 4 became the designated Rada is because it has the highest IP address on any physical 71 00:08:53,120 --> 00:08:56,990 interface this interface has an IP address of 10 1 1 1 72 00:09:01,360 --> 00:09:05,650 this interface on brought it to its 10 1 1 2 73 00:09:08,520 --> 00:09:15,740 this interface on Route 3 is 10 1 1 3 this interface and a force 10 on 1 1 4. 74 00:09:16,340 --> 00:09:21,530 But in addition it has an IP address on the serial interface of 10 1 2 1. 75 00:09:21,550 --> 00:09:24,710 So because it has the highest IP address of any physical interface 76 00:09:31,110 --> 00:09:38,280 it becomes the D.R. with this IP address. 77 00:09:38,310 --> 00:09:46,020 The reason why it didn't use this IP address is because this interface was added after the 0 SPF process 78 00:09:46,020 --> 00:09:47,250 had run. 79 00:09:47,250 --> 00:09:55,560 So the Rada I.D. had already been selected these two interfaces were up when OSP started this interface 80 00:09:55,770 --> 00:09:58,320 wasn't up when 0 SPF was started. 81 00:09:58,470 --> 00:10:01,980 So the Rada idea that was chosen was 10 1 to 1. 82 00:10:02,610 --> 00:10:10,530 So that proves that the Rada with the highest IP address of any physical interface will become the designated 83 00:10:10,530 --> 00:10:13,470 Rada on a segment when all the devices come up. 84 00:10:14,580 --> 00:10:21,690 Let's see if we can change that by manipulating priorities. 85 00:10:21,710 --> 00:10:25,330 I hope you found the video useful if you enjoyed it. 86 00:10:25,340 --> 00:10:26,610 Please like it. 87 00:10:26,850 --> 00:10:29,240 And please subscribe to my YouTube channel. 88 00:10:29,300 --> 00:10:30,770 I wish you all the very best.