1 00:00:00,890 --> 00:00:04,370 In this topology, we have two routers and two PCs. 2 00:00:05,030 --> 00:00:08,510 This is a newly configured topology. 3 00:00:09,200 --> 00:00:13,220 The rioters have just booted up and have no configuration. 4 00:00:13,520 --> 00:00:23,000 So for example, show IP interface brief on router one shows that all interfaces are shut down and no 5 00:00:23,000 --> 00:00:24,680 IP addresses are configured. 6 00:00:25,460 --> 00:00:33,680 What I'll do is no shut interface serial 2/0, the one interface on router one and I'll do something 7 00:00:33,680 --> 00:00:35,690 similar on router two. 8 00:00:37,820 --> 00:00:42,980 Rotor two also has no configuration, so no shut. 9 00:00:46,620 --> 00:00:49,020 Show IP interface brief. 10 00:00:50,860 --> 00:00:55,660 As you can see, the interfaces up up on both sides. 11 00:01:02,270 --> 00:01:05,209 Show interface serial two, slash a zero. 12 00:01:06,320 --> 00:01:13,780 What I'd like to point out is the encapsulation used, which is TLC by default on Cisco routers. 13 00:01:13,790 --> 00:01:18,680 Serial interfaces use Hdl-c as the encapsulation. 14 00:01:19,790 --> 00:01:26,600 So what we could do is go into that interface and give the writer an IP address of, say, ten .1.2.1. 15 00:01:28,310 --> 00:01:30,710 And use a slash 30 mask. 16 00:01:31,430 --> 00:01:33,740 I'll do something similar on router two. 17 00:01:34,940 --> 00:01:37,400 IP Address 10.1 or 2.2. 18 00:01:40,570 --> 00:01:40,840 Ken. 19 00:01:40,840 --> 00:01:41,620 Writer one Ping. 20 00:01:41,620 --> 00:01:44,770 Writer two Yes, it can. 21 00:01:45,330 --> 00:01:46,660 It can write a two ping. 22 00:01:46,660 --> 00:01:47,500 Writer one. 23 00:01:48,250 --> 00:01:52,210 Yes, it can show run interface serial two. 24 00:01:52,210 --> 00:01:53,380 Slash zero. 25 00:01:53,830 --> 00:01:56,650 All we had to do was no, shut the interface. 26 00:01:56,890 --> 00:02:00,520 We didn't have to configure an encapsulation. 27 00:02:00,730 --> 00:02:02,950 We didn't have to configure a clock rate. 28 00:02:03,100 --> 00:02:07,000 You only have to configure clock rate if you're using a back to back cable. 29 00:02:07,330 --> 00:02:12,740 And your rudder is the DC side of the cable here. 30 00:02:12,760 --> 00:02:14,410 Both sides of the dty. 31 00:02:14,620 --> 00:02:17,200 So we didn't have to configure a clock rate. 32 00:02:18,010 --> 00:02:21,220 Let's have a look at tllc frames. 33 00:02:21,550 --> 00:02:23,500 So I'll do a wireshark capture. 34 00:02:26,210 --> 00:02:28,430 On router one's serial interface. 35 00:02:34,380 --> 00:02:35,790 What we can see here. 36 00:02:37,540 --> 00:02:40,240 Is the protocol shown is slop. 37 00:02:44,440 --> 00:02:49,780 But notice we've got HLC and then the Sysco Slope Protocol, which is used for order configuration. 38 00:02:50,590 --> 00:02:53,230 Here we have a CDP message. 39 00:02:54,280 --> 00:02:58,720 So Sysco Hdl-c is the encapsulation used at layer two. 40 00:03:00,000 --> 00:03:06,060 Notice the protocol is referenced as 2000, which is Cisco Discovery Protocol. 41 00:03:06,860 --> 00:03:09,380 And we can see information about the device. 42 00:03:09,380 --> 00:03:17,150 So rather one is a 3725 and is using interface serial to slash zero. 43 00:03:18,770 --> 00:03:21,050 His rather to. 44 00:03:22,290 --> 00:03:25,260 Also using serial interface to slash zero. 45 00:03:28,140 --> 00:03:29,390 If we do a ping. 46 00:03:33,000 --> 00:03:36,240 We should see ICMP. 47 00:03:37,860 --> 00:03:38,870 And there we go. 48 00:03:38,880 --> 00:03:41,370 So, ICMP. 49 00:03:43,770 --> 00:03:45,960 At least to it's once again hdl-c. 50 00:03:45,990 --> 00:03:50,760 So if we look at the actual frame, the encapsulation type is hdl-c. 51 00:03:50,910 --> 00:03:52,560 It's not Ethernet. 52 00:03:53,340 --> 00:03:57,180 So on this one interface, we're using an hdl-c encapsulation. 53 00:03:57,780 --> 00:04:06,960 Notice the protocol reference is the famous x0 x 800, which means IP version for at least three years. 54 00:04:06,960 --> 00:04:08,160 IP version four. 55 00:04:08,520 --> 00:04:12,240 You can see the source IP address and destination IP address in the packet. 56 00:04:15,760 --> 00:04:18,019 The protocol sent is ICMP. 57 00:04:18,040 --> 00:04:19,540 You can see it's an echo. 58 00:04:19,720 --> 00:04:23,440 Here's the echo reply scrolling back to the top. 59 00:04:23,470 --> 00:04:25,330 It's once again hdl-c. 60 00:04:25,360 --> 00:04:26,770 There's the protocol type. 61 00:04:28,650 --> 00:04:36,570 Source IP addresses ten 112 going to ten 1 to 1 and it's an echo reply. 62 00:04:39,020 --> 00:04:44,810 So Cisco Hdl-c or C hdl-c has this protocol field. 63 00:04:45,870 --> 00:04:48,060 Denoting the higher layer protocol. 64 00:04:48,510 --> 00:04:50,160 That's IP version four. 65 00:04:51,120 --> 00:04:53,280 Let's configure IP version six. 66 00:04:53,280 --> 00:04:56,970 So IPV six, address 2001. 67 00:04:56,970 --> 00:04:59,070 Colon, colon one. 68 00:04:59,070 --> 00:05:00,330 Colon colon one. 69 00:05:00,330 --> 00:05:01,770 Slash 64. 70 00:05:03,490 --> 00:05:07,360 En route a to interface serial to slash zero. 71 00:05:07,840 --> 00:05:09,790 IPV six Address 2001. 72 00:05:09,790 --> 00:05:10,720 Colon one. 73 00:05:10,720 --> 00:05:12,100 Colon colon two. 74 00:05:12,970 --> 00:05:14,470 Slash 64. 75 00:05:16,310 --> 00:05:18,680 So ping 2001. 76 00:05:18,680 --> 00:05:19,340 Colon one. 77 00:05:19,340 --> 00:05:20,690 Colon two. 78 00:05:20,840 --> 00:05:22,130 Ping succeeds. 79 00:05:22,720 --> 00:05:24,850 And why shock capture. 80 00:05:26,110 --> 00:05:27,190 We see. 81 00:05:28,230 --> 00:05:30,210 The ICMP messages. 82 00:05:33,470 --> 00:05:41,300 So this is the ping from rata one to rata to notice the protocol type 86 D It's a different protocol 83 00:05:41,300 --> 00:05:44,210 type to IP version for Cisco. 84 00:05:44,370 --> 00:05:51,560 Hdl-c allows you to run multiple higher layer protocols across the same link because of this protocol 85 00:05:51,560 --> 00:05:52,250 field. 86 00:05:52,640 --> 00:05:55,340 So once again, there is IP version six. 87 00:05:56,930 --> 00:06:07,160 And scrolling up here is IP version four and here is CDP, all using different protocol types. 88 00:06:07,490 --> 00:06:12,500 So the layer two encapsulation here is referencing a higher layer protocol. 89 00:06:13,310 --> 00:06:16,940 We would see something similar on an Ethernet frame. 90 00:06:16,940 --> 00:06:28,940 So on router one interface, if zero slash or zero no shut IP address ten 1112452452450 91 00:06:29,570 --> 00:06:36,920 on the PC will give it an IP address of 10.11 2011 with a mosque. 92 00:06:39,330 --> 00:06:43,440 And I'll set the gateway to ten .1.11. 93 00:06:45,210 --> 00:06:48,120 So ping 10.1 and 1.1. 94 00:06:49,040 --> 00:06:51,890 PC can ping rather one. 95 00:06:52,130 --> 00:06:56,810 And if we start to capture on that interface, so we're going to capture traffic on the router. 96 00:07:01,010 --> 00:07:03,200 Notice the frame is ethernet to. 97 00:07:04,220 --> 00:07:05,750 Let's send a ping again. 98 00:07:06,550 --> 00:07:08,650 So there is our ICMP packet. 99 00:07:08,680 --> 00:07:16,360 Notice the protocol type for IP version four is zero 800, which is what we saw. 100 00:07:17,340 --> 00:07:19,230 On the tllc frame. 101 00:07:20,830 --> 00:07:22,150 So here's Hdl-c. 102 00:07:22,180 --> 00:07:23,770 Notice the protocol field. 103 00:07:24,100 --> 00:07:31,600 So when you send packets across a rudder, that shows you quite clearly that the layer two encapsulation 104 00:07:31,600 --> 00:07:35,410 changes, but the high layer protocols are maintained or kept. 105 00:07:36,370 --> 00:07:39,550 Encapsulation used here is Ethernet two. 106 00:07:39,910 --> 00:07:42,970 Encapsulation used here is LC. 107 00:07:43,240 --> 00:07:48,880 Encapsulation here would be Ethernet to once again in this example. 108 00:07:50,740 --> 00:07:54,970 So in order to interface f0/0 no shut IP address. 109 00:07:54,970 --> 00:07:57,580 Ten .1.3.1. 110 00:07:59,020 --> 00:08:02,290 As an example on PC two. 111 00:08:02,680 --> 00:08:06,130 IP address 10.1 3.12. 112 00:08:07,660 --> 00:08:11,470 Put the mask in default gateway. 113 00:08:13,890 --> 00:08:16,380 Paying 10.1 or 3.1. 114 00:08:16,950 --> 00:08:17,910 That works. 115 00:08:19,640 --> 00:08:27,020 Well, enable a writing protocol here quickly to allow the writers to talk to each other. 116 00:08:28,730 --> 00:08:32,960 And this will give us another protocol to capture in Wireshark. 117 00:08:36,890 --> 00:08:39,679 So enable OSPF on all interfaces. 118 00:08:41,740 --> 00:08:45,730 Start a CAPTCHA on this interface. 119 00:08:48,090 --> 00:08:54,480 So we have three Wireshark captures going serial interface, this Ethernet interface and this Ethernet 120 00:08:54,480 --> 00:08:55,230 interface. 121 00:08:56,100 --> 00:09:04,260 PC one should, if OSPF has converged, be able to ping PC two, which it can. 122 00:09:04,890 --> 00:09:06,810 So the pings are succeeding. 123 00:09:08,190 --> 00:09:12,540 Let's have a look at the frame over here on the Ethernet segment. 124 00:09:14,570 --> 00:09:16,040 So there's the frame. 125 00:09:16,460 --> 00:09:19,400 You can see the Ethernet type is Ethernet to. 126 00:09:21,020 --> 00:09:26,180 Source Mac address destination MAC address, which is the router protocol is IP version four. 127 00:09:27,550 --> 00:09:29,800 Just to prove that that's the router. 128 00:09:32,150 --> 00:09:35,120 Show interface if 0/0. 129 00:09:38,910 --> 00:09:42,360 Notice the MAC address is C 201. 130 00:09:45,190 --> 00:09:49,750 3fe80000, which is correct. 131 00:09:50,440 --> 00:09:56,710 So the PC is sending the traffic to the local router using Ethernet too. 132 00:09:56,920 --> 00:09:58,930 In other words, ethernet encapsulation. 133 00:10:00,350 --> 00:10:01,530 At least three. 134 00:10:01,550 --> 00:10:08,600 The source and destination of the two pieces on the TLC capture. 135 00:10:12,010 --> 00:10:16,570 There's the same IP addresses of the PCs at Layer three. 136 00:10:17,300 --> 00:10:23,810 But notice at layer two, the encapsulation is TLC and there are no MAC addresses. 137 00:10:23,840 --> 00:10:27,130 MAC addresses are only used on Ethernet. 138 00:10:27,140 --> 00:10:30,140 They're not used in hdl-c. 139 00:10:30,590 --> 00:10:32,640 Hdl-c lengths are point to point. 140 00:10:32,660 --> 00:10:35,270 There's no need to have MAC addresses. 141 00:10:35,810 --> 00:10:40,880 Anything that you send out of this interface is going to arrive on this interface and vice versa. 142 00:10:41,120 --> 00:10:48,320 Whereas Ethernet allows multiple devices to connect to the same segment, so there's no need to have 143 00:10:48,320 --> 00:10:49,460 MAC addresses. 144 00:10:50,400 --> 00:10:58,140 In Hdl-c it simply references the higher layer protocol and specifies that this is a unicast packet. 145 00:10:58,710 --> 00:11:00,750 What about on the side? 146 00:11:03,640 --> 00:11:09,160 So here's the ping source and destination IP addresses are the same. 147 00:11:09,640 --> 00:11:12,340 Notice, however, that it's Ethernet once again. 148 00:11:12,340 --> 00:11:14,080 So Ethernet too, in this case. 149 00:11:15,380 --> 00:11:17,840 The source Mac address is rather to. 150 00:11:19,780 --> 00:11:20,170 Show. 151 00:11:20,170 --> 00:11:20,890 Interface. 152 00:11:21,190 --> 00:11:22,090 Fast Ethernet. 153 00:11:22,180 --> 00:11:22,480 Zero. 154 00:11:22,900 --> 00:11:23,710 Zero. 155 00:11:25,150 --> 00:11:26,210 Notice the Mac address. 156 00:11:26,230 --> 00:11:27,040 See? 157 00:11:28,680 --> 00:11:32,790 2023840. 158 00:11:33,090 --> 00:11:34,260 That's the router. 159 00:11:34,770 --> 00:11:42,480 Talking to the PC in this case, PC to the Ethernet type field specifies IP version four as the high 160 00:11:42,480 --> 00:11:43,500 layer protocol. 161 00:11:43,800 --> 00:11:49,590 And here's our IP packet and here's the ICMP information. 162 00:11:50,970 --> 00:11:51,660 So. 163 00:11:52,630 --> 00:11:56,410 The encapsulation changes on every link. 164 00:11:57,130 --> 00:12:00,190 Mac addresses are used on the Ethernet segments. 165 00:12:00,670 --> 00:12:03,850 MAC addresses are not used in hdl-c.