1 00:00:09,390 --> 00:00:15,300 This is one of multiple IP version 6 troubleshooting videos in this network. 2 00:00:15,300 --> 00:00:22,800 We've been told that a write of one on the left cannot ping the looped back of a rudder three the rudder 3 00:00:22,830 --> 00:00:31,510 on the right so let's verify that now because this is IP version 6 of rather than IP version 4 notice 4 00:00:31,600 --> 00:00:35,670 no IP version 4 rights exist in the writing table. 5 00:00:35,800 --> 00:00:44,290 We need to do all our testing using IP version 6 something like paying the loop back of rudder 3 we 6 00:00:44,290 --> 00:00:45,730 get a failure. 7 00:00:45,730 --> 00:00:51,320 We are not able to ping the loop back of rudder 3. 8 00:00:51,590 --> 00:00:56,050 Let's do a trace right and see how far we get okay. 9 00:00:56,060 --> 00:01:02,260 So what do you think about to this output what's going on here. 10 00:01:02,260 --> 00:01:10,210 Notice we're told that the destination was not found inside the max hop count diameter so let's do that 11 00:01:10,210 --> 00:01:11,430 again. 12 00:01:11,440 --> 00:01:12,670 Notice what's happening. 13 00:01:13,690 --> 00:01:17,220 So where is the traffic going. 14 00:01:17,380 --> 00:01:21,410 Now this is a good example of a rotting loop. 15 00:01:21,460 --> 00:01:24,790 So if we scroll up notice what's happening. 16 00:01:24,790 --> 00:01:26,950 Traffic it goes to RADA too. 17 00:01:27,160 --> 00:01:34,760 Then it goes to RADA one then two wrote it two then two brought a one back to wrote it to back to RADA 18 00:01:34,780 --> 00:01:37,000 one and so forth and so on. 19 00:01:37,030 --> 00:01:39,490 So we have a loop taking place here. 20 00:01:40,940 --> 00:01:47,750 So let's have a look at the writing table show IP these six right rudder one has a default route to 21 00:01:47,750 --> 00:01:52,980 2001 Column 1 Column column 2 which is rather 2. 22 00:01:53,300 --> 00:02:05,420 Hence the traffic is being sent to RADA too but on rudder to show IP v 6 around can you see the problem 23 00:02:05,420 --> 00:02:06,250 here. 24 00:02:06,320 --> 00:02:14,800 Pause the video if you need to but see if you can find the problem OK so we have a static default route 25 00:02:14,900 --> 00:02:22,040 to write a three That looks okay there's a static round to the loop back of rudder one that also looks 26 00:02:22,040 --> 00:02:28,630 okay here's a static route to the loop back of rotors three but that looks wrong. 27 00:02:28,640 --> 00:02:35,270 Notice where it's pointing it's saying to get to the Loop pack of Rider 3 we need to go via route of 28 00:02:35,260 --> 00:02:36,350 1. 29 00:02:36,410 --> 00:02:42,950 So that's definitely not right and it's kind of redundant because we have this default front in the 30 00:02:42,950 --> 00:02:44,210 routing table. 31 00:02:44,210 --> 00:02:55,310 So show run pipe include route we need to get rid of this route and either fix the next hop or simply 32 00:02:55,310 --> 00:03:00,930 remove it and rely on the default draft here. 33 00:03:01,010 --> 00:03:02,630 So Ken wrote a one paying 34 00:03:05,280 --> 00:03:07,250 the loop backup Rider 3. 35 00:03:07,390 --> 00:03:19,880 OK the pings are still failing let's do a trace to that address the packet gets sent to brought to you 36 00:03:20,270 --> 00:03:22,610 but then goes nowhere else. 37 00:03:22,610 --> 00:03:27,320 So it doesn't look like it gets any further based on that output. 38 00:03:27,530 --> 00:03:32,180 So Ken wrote it to ping the loop back of wrought a three 39 00:03:35,080 --> 00:03:35,830 yes it can. 40 00:03:36,540 --> 00:03:41,220 So rather to keeping the loop back wrote a three but rather one containing the loop back of rather three 41 00:03:42,690 --> 00:03:50,130 so on rather three letters to a debug and check if the traffic is actually getting two rather three 42 00:03:50,580 --> 00:03:57,970 from rather one and we can see that it is so we can see that the pings are arriving at a rather three 43 00:03:58,590 --> 00:04:05,940 but it looks like the reply is not getting back to broader one so rather three received an echo request 44 00:04:06,090 --> 00:04:13,440 from 2001 Colin one color in column one which is right one destination is the loop back of rudder three 45 00:04:13,870 --> 00:04:22,490 so that the echo is sent but it's not getting back again so let's turn off debugging and let's do a 46 00:04:22,490 --> 00:04:30,950 debug HPV six packet now in the real world you need to be very careful doing this I'm going to send 47 00:04:31,040 --> 00:04:38,540 a single packet and let's see what happens again be very careful doing this in the real world you'll 48 00:04:38,540 --> 00:04:45,240 get a lot of output even in the small network if we don't turn off debugging we might get a lot of output 49 00:04:45,630 --> 00:04:54,010 on the console so there's the debug I sent a single ping from right I want to write a three we've got 50 00:04:54,010 --> 00:05:02,380 a destination lookup for that the rudder sees that as a local network connected to the loop back so 51 00:05:02,380 --> 00:05:11,280 that looks good but notice here IP these six forward no right to destination 2001 Colin one Colin Colin 52 00:05:11,290 --> 00:05:22,990 one source is the loop back of rudder three destination is the gigabit 00 interface of rudder one and 53 00:05:22,990 --> 00:05:30,370 we're told that there's no valid dropped so it doesn't look like a router three knows how to get back 54 00:05:30,430 --> 00:05:38,610 to rudder one so show IP these six right is there a raft in the routing table to get back to rudder 55 00:05:38,930 --> 00:05:39,900 one. 56 00:05:40,330 --> 00:05:41,770 And the answer is No. 57 00:05:42,010 --> 00:05:53,170 We have this static raft which would allow rather three to ping the loop back of rudder one but it can't 58 00:05:53,170 --> 00:05:56,530 paying two thousand and one. 59 00:05:56,530 --> 00:06:07,000 So what we need to do is add a static front to 2001 column one colon colon zero slash 64 and send that 60 00:06:07,060 --> 00:06:12,910 to rudder to now let's do the ping again. 61 00:06:12,990 --> 00:06:14,610 Notice the pings succeeded 62 00:06:17,600 --> 00:06:24,530 and without using the repeat command the pings now succeed so we can get to the loop back of rudder 63 00:06:24,530 --> 00:06:32,130 three and we can get to the physical interface of rudder three so be careful with pings. 64 00:06:32,300 --> 00:06:36,180 This applies to both IP version 4 and IP version 6. 65 00:06:36,260 --> 00:06:42,420 Just because I can send traffic to you doesn't mean that you know how to send traffic back to me. 66 00:06:42,440 --> 00:06:48,080 Both sides need rots in the writing table to enable two way communication. 67 00:06:48,080 --> 00:06:49,610 I hope you enjoyed this video. 68 00:06:49,610 --> 00:06:52,620 If it was of benefit to you please like it. 69 00:06:52,620 --> 00:06:55,310 And please subscribe to my YouTube channel. 70 00:06:55,310 --> 00:06:57,190 I wish you all the very best.