1 00:00:00,860 --> 00:00:03,440 At the moment, rather one acting as PC. 2 00:00:03,440 --> 00:00:06,590 One can ping root of five acting as PC two. 3 00:00:07,460 --> 00:00:08,900 I'll turn off these bugs. 4 00:00:11,750 --> 00:00:14,360 Let's have a look at some show commands. 5 00:00:14,780 --> 00:00:19,610 So first command on router to show interface tunnel zero. 6 00:00:21,850 --> 00:00:23,470 Tunnel zero is up, up. 7 00:00:23,800 --> 00:00:25,510 The hardware type is tunnel. 8 00:00:25,600 --> 00:00:29,890 The IP address on the interface is 10.1 to 3 to 130. 9 00:00:32,020 --> 00:00:34,330 The encapsulation type is tunnel. 10 00:00:34,810 --> 00:00:40,520 The tunnel sources 4.1.121 tunnel destination is four to 1 to 2.2. 11 00:00:41,140 --> 00:00:46,810 The protocol and transport is gry over IP version four. 12 00:00:47,110 --> 00:00:54,880 Notice the empty yew has been reduced for this interface because of the headers used in gray. 13 00:00:56,720 --> 00:01:03,350 The empty u four serial to slash zero or maximum transmission unit four. 14 00:01:03,350 --> 00:01:05,090 Interface 2/0. 15 00:01:05,930 --> 00:01:07,580 Is 1500 bytes. 16 00:01:07,790 --> 00:01:09,270 But the MTU. 17 00:01:11,190 --> 00:01:14,130 For the jury tunnel is 1514. 18 00:01:14,550 --> 00:01:26,010 So 1550 minus one 514 gives us 36 points because of the additional headers used in January, the BTU 19 00:01:26,010 --> 00:01:27,110 is reduced. 20 00:01:27,120 --> 00:01:32,430 In other words, only smaller packets can be transmitted across the cereal link because of the additional 21 00:01:32,430 --> 00:01:34,410 headers added by jury. 22 00:01:35,300 --> 00:01:41,990 Originally we only have a single IP header, but now we have an additional IP header called the delivery 23 00:01:41,990 --> 00:01:44,630 header as well as the header. 24 00:01:45,380 --> 00:01:48,320 And we can see that by doing a Wireshark capture. 25 00:01:52,900 --> 00:01:57,460 So I'm going to capture traffic on cereal to slash one on router three. 26 00:02:01,390 --> 00:02:07,480 Send a ping from router one acting as PC one two out of five acting as PC to. 27 00:02:13,060 --> 00:02:14,140 Here's the ping. 28 00:02:14,630 --> 00:02:20,800 Now remember, originally we would only have a single IP version for header with the payload, but now 29 00:02:20,800 --> 00:02:26,650 we have both the header as well as the order header or delivery header. 30 00:02:26,860 --> 00:02:29,410 So the original packet over here. 31 00:02:30,520 --> 00:02:32,650 As received by writer to. 32 00:02:38,020 --> 00:02:40,930 Doesn't include the gory headers. 33 00:02:41,320 --> 00:02:43,300 So when we do that ping again. 34 00:02:49,410 --> 00:02:52,560 This is the first Ethernet interface on router two. 35 00:02:55,450 --> 00:03:01,450 We can see the ping message with the standard IP version for header and Ethernet header. 36 00:03:03,140 --> 00:03:11,330 But when that goes across the cereal interface, notice Cisco Hdl-c, we see the original header and 37 00:03:11,330 --> 00:03:12,140 payload. 38 00:03:12,260 --> 00:03:13,580 So there's the ping. 39 00:03:15,340 --> 00:03:18,010 But notice once again the additional header. 40 00:03:18,550 --> 00:03:21,340 So we've got the delivery header. 41 00:03:22,240 --> 00:03:23,890 As well as the gry header. 42 00:03:24,850 --> 00:03:29,980 So additional headers have been added when compared to the original packet. 43 00:03:30,880 --> 00:03:34,300 Because of that, the empty view is reduced. 44 00:03:34,570 --> 00:03:43,000 You can only send a maximum packet size of 1514 bytes because of the additional headers. 45 00:03:43,240 --> 00:03:45,220 So once again, on serial 46 00:03:47,230 --> 00:03:50,830 2/0, the MTU is 1500 bytes. 47 00:03:52,120 --> 00:03:58,660 But on the tunnel interface, it's 1514 bytes because of the additional headers. 48 00:04:00,320 --> 00:04:05,870 You can also see some information by using the command show IP interface tunnel zero. 49 00:04:07,430 --> 00:04:08,420 Scrolling up. 50 00:04:09,880 --> 00:04:13,330 Has the Comand tunnel interface zero zero is up up. 51 00:04:13,690 --> 00:04:18,730 IP addresses 10.1 to 3.1 slash 30 broadcast is this. 52 00:04:20,130 --> 00:04:22,830 Aim to use 1476 bytes once again. 53 00:04:23,730 --> 00:04:30,150 Multicast reserved groups joined includes 2 to 4 zero zero ten, which if you remember, is the multicast 54 00:04:30,150 --> 00:04:31,620 group for IRP. 55 00:04:31,980 --> 00:04:38,760 IRP is able to form a neighbor relationship across this tunnel interface in a very similar way to how 56 00:04:38,760 --> 00:04:45,750 you would form it across a serial interface, because this is a point to point link logically directly 57 00:04:45,750 --> 00:04:47,370 from one router to the other. 58 00:04:48,060 --> 00:04:56,400 So as an example, show IP copy neighbor, right two has a neighbor relationship with router four on 59 00:04:56,490 --> 00:05:03,960 this IP address and not on this IP address because the neighbor relationship is formed across the tunnel 60 00:05:04,470 --> 00:05:07,680 show IP JP topology. 61 00:05:08,220 --> 00:05:19,770 We have learnt a Route ten 1 to 0 via ten 132 through tunnel zero and once again rather one is able 62 00:05:19,770 --> 00:05:28,410 to ping router five acting as a PC when we do a trace to ten one, two, two, notice the trace goes 63 00:05:28,410 --> 00:05:36,480 to router two then to write a four through the tunnel and then to right a five router three is not seen 64 00:05:36,480 --> 00:05:43,920 at all in the trace because logically router two is directly connected to router four in the same way. 65 00:05:43,980 --> 00:05:49,170 We're out of five when tracing to ten 111 sends the traffic to write a four. 66 00:05:50,420 --> 00:05:55,100 Then a logically to write a to and then to write a one.