1 00:00:00,810 --> 00:00:04,530 There are two main types of encapsulation that we'll discuss in this course. 2 00:00:04,770 --> 00:00:09,510 The first one is Hdl-c or high level data link control. 3 00:00:09,660 --> 00:00:17,340 This is a layer two encapsulation once again that can be used across a least line providing layer one 4 00:00:17,340 --> 00:00:21,240 service or connectivity from one site to another. 5 00:00:21,510 --> 00:00:28,410 Now you need to be aware that Cisco have extended the industry standard of version of Hdl-c by adding 6 00:00:28,410 --> 00:00:31,230 an extra field called the type field. 7 00:00:31,770 --> 00:00:38,760 Hdl-c is a very simple encapsulation, and I'll demonstrate a Wireshark capture of the frame in a moment. 8 00:00:38,760 --> 00:00:45,150 But as an example, we have a flag field address, field control field and a frame check sequence field. 9 00:00:45,150 --> 00:00:48,480 Cisco have added a type field to the frame. 10 00:00:48,480 --> 00:00:53,880 So this is different to the ISO industry standard HDL-C Protocol. 11 00:00:54,090 --> 00:01:00,060 Cisco devices do use the Cisco HDL-C or C Hdl-c version by default. 12 00:01:00,240 --> 00:01:05,250 And you'll notice it's very easy to set up a serial link using this encapsulation. 13 00:01:05,610 --> 00:01:10,950 You essentially just have to put an IP address on your router interfaces and no shut the interfaces 14 00:01:10,950 --> 00:01:13,020 to get them to communicate with each other. 15 00:01:13,530 --> 00:01:19,740 If you want to connect Cisco routers to non Cisco routers, you're going to want to change the encapsulation 16 00:01:19,740 --> 00:01:24,300 to PPTP, which is an industry standard version of encapsulation. 17 00:01:24,570 --> 00:01:32,610 Now the reason why Cisco added the proprietary field is to allow multiple high layer protocols to traverse 18 00:01:32,610 --> 00:01:34,110 the link at the same time. 19 00:01:34,470 --> 00:01:42,840 So in other words, if you want to run IP version four and IP version six across a serial link simultaneously, 20 00:01:42,930 --> 00:01:49,710 the routers need a type field to differentiate the frames that belong to IP version four versus the 21 00:01:49,710 --> 00:01:56,490 frames that belong to IP version six when the router receives an IP version for packet across a serial 22 00:01:56,490 --> 00:01:57,000 link. 23 00:01:57,000 --> 00:02:01,830 So in this example, router two receives an IP version for packet from router one. 24 00:02:01,830 --> 00:02:09,180 Router two needs to know that that packet should be processed by the IP version for protocol stack on 25 00:02:09,180 --> 00:02:09,900 the router. 26 00:02:10,169 --> 00:02:17,370 When it receives a IP version six packet, it needs to know that the packet is destined to the IP version 27 00:02:17,370 --> 00:02:22,440 six protocol stack, and that's what the top field provides. 28 00:02:22,470 --> 00:02:29,520 It essentially allows the routers to differentiate between multiple higher layer protocols, and hence 29 00:02:29,520 --> 00:02:33,300 Cisco extended the protocol to allow that functionality. 30 00:02:33,630 --> 00:02:40,350 The industry standard version of Hdl-c doesn't have that type field denoting high layer protocols. 31 00:02:40,680 --> 00:02:44,010 Now it's very simple to configure Hdl-c between two browsers. 32 00:02:44,070 --> 00:02:50,040 You would type as an example on router one, enable confetti interface and the relevant interface. 33 00:02:50,040 --> 00:02:56,280 In this example, serial 1/0, you would configure the IP address on the serial interface. 34 00:02:56,430 --> 00:03:03,420 So IP address 10.1 or 2.1 with the mask 2.5245245252. 35 00:03:03,420 --> 00:03:10,020 As an example, which would be better than slash 24 and then you specify encapsulation hdl-c so it's 36 00:03:10,020 --> 00:03:14,580 as simple as that to configure Hdl-c All you type is encapsulation. 37 00:03:14,580 --> 00:03:18,330 Hdl-c And that is done by default for you. 38 00:03:18,360 --> 00:03:20,730 So you don't actually need to configure that at all.