WEBVTT 0:00:07.220000 --> 0:00:10.800000 This video, which is the first video in the Cisco Certified Technician 0:00:10.800000 --> 0:00:14.360000 Series for routing and switching, I'm going to go over the topic which 0:00:14.360000 --> 0:00:19.420000 is in section one called Identifying Interfaces on Cisco Devices. 0:00:19.420000 --> 0:00:25.940000 Once again, my name in case you've forgotten is Keith Bogart and I will 0:00:25.940000 --> 0:00:28.540000 be your instructor for this series of videos. 0:00:28.540000 --> 0:00:30.820000 So in this video, what would I like to talk about? 0:00:30.820000 --> 0:00:32.940000 Well, I'd like to talk about several things. 0:00:32.940000 --> 0:00:35.200000 Number one, what is an interface? 0:00:35.200000 --> 0:00:38.720000 You probably already know this, but just in case, I want to cover all 0:00:38.720000 --> 0:00:42.740000 the bases here. Where some common types of interfaces you would find on 0:00:42.740000 --> 0:00:46.840000 Cisco routers and switches, how you can identify them visually, how you 0:00:46.840000 --> 0:00:50.600000 can identify them based on knowing what kind of cable it connects to, 0:00:50.600000 --> 0:00:54.840000 and then we'll also talk about port numbering conventions. 0:00:54.840000 --> 0:00:59.440000 So, if you are truly a Cisco Certified Technician, you should be able 0:00:59.440000 --> 0:01:01.660000 to answer a couple of questions. 0:01:01.660000 --> 0:01:04.840000 For example, if someone gave you this question, they said, hey, you need 0:01:04.840000 --> 0:01:10.760000 to swap out a faulty PA-4T on your Cisco 7206 router. 0:01:10.760000 --> 0:01:14.980000 Given this router right here, given this image, which of the letters correctly 0:01:14.980000 --> 0:01:18.620000 identifies the port adapter that needs to be replaced? 0:01:18.620000 --> 0:01:21.900000 By the time we're done with this video, you'll be able to answer that. 0:01:21.900000 --> 0:01:25.360000 Another type of question that relates to understanding and recognizing 0:01:25.360000 --> 0:01:27.500000 interfaces would be the following. 0:01:27.500000 --> 0:01:32.320000 You need to swap out the port adapter that contains controller T3, 0, 0:01:32.320000 --> 0:01:34.060000 slash 2, slash 0. 0:01:34.060000 --> 0:01:37.440000 Once again, given the image below, which of the letters identifies the 0:01:37.440000 --> 0:01:41.040000 correct port adapter that needs to be replaced? 0:01:41.040000 --> 0:01:44.300000 Now, to answer this question requires a different skill set than the previous 0:01:44.300000 --> 0:01:47.360000 question. You'd really need to have an understanding of the naming and 0:01:47.360000 --> 0:01:52.440000 numbering convention of this particular model of Cisco router. 0:01:52.440000 --> 0:01:54.640000 So, what is an interface? 0:01:54.640000 --> 0:01:58.440000 A very simple basic question, but one you definitely need to know. 0:01:58.440000 --> 0:02:00.520000 An interface is basically a connector. 0:02:00.520000 --> 0:02:05.700000 A connector to a device that provides either power or signaling to that 0:02:05.700000 --> 0:02:10.220000 device. Now, even if you've never touched or seen a router or a switch 0:02:10.220000 --> 0:02:13.300000 before, you're already quite familiar with interfaces. 0:02:13.300000 --> 0:02:17.500000 For example, here's a couple of very common interfaces that provide power 0:02:17.500000 --> 0:02:22.740000 to devices. An interface that provides power to your tablet or your laptop. 0:02:22.740000 --> 0:02:26.780000 So, in this case, electrical energy is coming in and via plugging into 0:02:26.780000 --> 0:02:30.400000 this port, this interface, it's powering up the device. 0:02:30.400000 --> 0:02:33.800000 Another type of interface you're probably familiar with are audio and 0:02:33.800000 --> 0:02:35.600000 video interfaces. 0:02:35.600000 --> 0:02:40.820000 Here we have a video HDMI port, which once again is receiving electrical 0:02:40.820000 --> 0:02:44.040000 signaling. But this time, the electrical signaling is not designed to 0:02:44.040000 --> 0:02:45.340000 power the device. 0:02:45.340000 --> 0:02:49.180000 The electrical signaling is formatted in such a way that it represents 0:02:49.180000 --> 0:02:51.920000 video, video signals. 0:02:51.920000 --> 0:02:55.920000 And then the lower right, we have an audio port, which once again is receiving 0:02:55.920000 --> 0:03:00.040000 electricity, electrical signaling, but now the electrical signaling is 0:03:00.040000 --> 0:03:04.220000 using, is conveying audio information. 0:03:04.220000 --> 0:03:05.700000 So, how are Cisco devices different? 0:03:05.700000 --> 0:03:09.900000 Well, interfaces on Cisco routers and switches certainly also can provide 0:03:09.900000 --> 0:03:11.660000 power or signaling. 0:03:11.660000 --> 0:03:15.480000 Now, typically, when we're trying to identify interfaces on routers and 0:03:15.480000 --> 0:03:19.720000 switches, we're not really looking for interfaces like we just saw, which 0:03:19.720000 --> 0:03:26.340000 are natively supporting video, like HDMI or DVI interfaces, or natively 0:03:26.340000 --> 0:03:30.020000 supporting audio like we saw in those other interfaces. 0:03:30.020000 --> 0:03:33.720000 Typically, the interfaces we're concerned with are either interfaces that 0:03:33.720000 --> 0:03:37.740000 are receiving power, for example, a power adapter could be broken, the 0:03:37.740000 --> 0:03:43.180000 pins could be bent or damaged, or interfaces that carry signaling that 0:03:43.180000 --> 0:03:50.320000 conveys data. Now, that data might actually be audio, video, voice, or 0:03:50.320000 --> 0:03:54.560000 actual user data like web browsing or email, but still, we're typically 0:03:54.560000 --> 0:03:56.860000 talking about a data interfaces. 0:03:56.860000 --> 0:04:01.060000 So, as far as identifying power interfaces on routers or switches, I probably 0:04:01.060000 --> 0:04:03.740000 don't have to go into this in any great detail. 0:04:03.740000 --> 0:04:07.880000 Chances are that in your lifetime, you have plugged something in to the 0:04:07.880000 --> 0:04:12.740000 back of a TV or a router you have at home or something, and the power 0:04:12.740000 --> 0:04:17.560000 interface on a Cisco router or switch looks pretty much similar to that. 0:04:17.560000 --> 0:04:21.020000 So, if you were told, hey, this particular router or switch, we suspect 0:04:21.020000 --> 0:04:24.680000 that the power interface is damaged in some way. 0:04:24.680000 --> 0:04:28.240000 Go take a look at it, see if any of the pins are broken or damaged or 0:04:28.240000 --> 0:04:29.720000 snapped off or something. 0:04:29.720000 --> 0:04:32.460000 Well, you'd be looking for the same kind of interface you'd normally expect 0:04:32.460000 --> 0:04:35.880000 to look for on your laptop or on your TV set. 0:04:35.880000 --> 0:04:40.040000 Basically, a three-pronged or maybe a four- or two-pronged interface that 0:04:40.040000 --> 0:04:43.020000 connects to a power outlet, like we see right here. 0:04:43.020000 --> 0:04:45.620000 Now, where things can get a little bit tricky is when you're asked to 0:04:45.620000 --> 0:04:50.940000 identify a data interface, so that you can either inspect it to see if 0:04:50.940000 --> 0:04:54.640000 there's something wrong with it or swap out the module that holds that 0:04:54.640000 --> 0:04:58.660000 interface. Now, data interfaces on Cisco routers and switches come in 0:04:58.660000 --> 0:05:05.460000 a wide variety of form factors, and different criteria define these form 0:05:05.460000 --> 0:05:07.500000 factors. Now, what do I mean by form factor? 0:05:07.500000 --> 0:05:11.700000 I mean, like, how big or how small it is, how many pins it has, whether 0:05:11.700000 --> 0:05:15.680000 it's a male or a female interface, whether it's designed to accept copper 0:05:15.680000 --> 0:05:20.900000 cabling or fiber optic cabling, wide variety of things dictate that. 0:05:20.900000 --> 0:05:24.120000 For example, is it a LAN or a WAN interface? 0:05:24.120000 --> 0:05:27.520000 The form factor will be related to that. 0:05:27.520000 --> 0:05:32.460000 For example, LAN interfaces typically don't have to push as much power 0:05:32.460000 --> 0:05:36.080000 through that interface because the two devices that cable is connecting 0:05:36.080000 --> 0:05:38.060000 are fairly close to each other. 0:05:38.060000 --> 0:05:41.780000 Whereas a WAN interface is connecting that interface to something that 0:05:41.780000 --> 0:05:46.700000 might be miles away, so it has to carry a lot more energy, either light 0:05:46.700000 --> 0:05:51.220000 or electrical energy, through that interface to get the signal that great 0:05:51.220000 --> 0:05:55.200000 distance. That will affect the form factor of that interface. 0:05:55.200000 --> 0:05:58.980000 Also, the signaling requirements for pins, right? 0:05:58.980000 --> 0:06:02.700000 So, if we're talking about an interface that carries electrical energy, 0:06:02.700000 --> 0:06:06.840000 pretty much most of those types of interfaces have at least two connectors, 0:06:06.840000 --> 0:06:10.820000 if not more. So, the quantity of pins may be different. 0:06:10.820000 --> 0:06:13.960000 Some protocols say, hey, look, we're going to carry all of our data and 0:06:13.960000 --> 0:06:16.800000 are signaling on one electrical current. 0:06:16.800000 --> 0:06:19.360000 Others say, hey, we're going to use multiple pins. 0:06:19.360000 --> 0:06:23.460000 This pin here is going to be used for a separate purpose than this pin 0:06:23.460000 --> 0:06:27.100000 over here. That's also going to dictate the form factor. 0:06:27.100000 --> 0:06:32.260000 Is that interface carrying light, electricity, or radio frequency? 0:06:32.260000 --> 0:06:34.980000 If it's radio frequency, you're not going to see an interface at all. 0:06:34.980000 --> 0:06:38.080000 It's going to be internal, probably on the circuit board, behind a front 0:06:38.080000 --> 0:06:40.200000 panel of the chassis or something. 0:06:40.200000 --> 0:06:41.880000 And also space constraints. 0:06:41.880000 --> 0:06:44.880000 Some interfaces take a lot of space because they have to plug in cables 0:06:44.880000 --> 0:06:49.740000 that have a lot of pins, sometimes upwards of 100 pins on one physical 0:06:49.740000 --> 0:06:51.820000 cable that's plug into a port. 0:06:51.820000 --> 0:06:56.020000 That can be a fairly wide or tall interface. 0:06:56.020000 --> 0:07:00.180000 Other interfaces are specifically designed with space constraints in mind. 0:07:00.180000 --> 0:07:04.360000 So, you can have a lot of interfaces crammed into a very narrow space 0:07:04.360000 --> 0:07:07.420000 on the line card or on the chassis. 0:07:07.420000 --> 0:07:09.940000 So, where are these interfaces located? 0:07:09.940000 --> 0:07:12.540000 Where would you typically find them on a router switch? 0:07:12.540000 --> 0:07:14.960000 Well, they can go in a couple of different places. 0:07:14.960000 --> 0:07:18.780000 Number one, a lot of interfaces are built directly into the chassis itself. 0:07:18.780000 --> 0:07:22.840000 For example, here you see a couple of Ethernet ports that are built directly 0:07:22.840000 --> 0:07:24.580000 into the chassis. 0:07:24.580000 --> 0:07:26.820000 Now, what do I mean by into the chassis? 0:07:26.820000 --> 0:07:30.320000 What I mean by that is when you take a look at these ports right here, 0:07:30.320000 --> 0:07:37.740000 these ports, what is holding those ports, is not any removable device. 0:07:37.740000 --> 0:07:40.560000 It's right there on the router or switch itself. 0:07:40.560000 --> 0:07:42.560000 You can't pull those ports out. 0:07:42.560000 --> 0:07:46.640000 You can't change them for a different kind of a port or an interface. 0:07:46.640000 --> 0:07:51.160000 It's hardwired and built into that router or switch itself. 0:07:51.160000 --> 0:07:54.220000 Other types of interfaces can be on removable media. 0:07:54.220000 --> 0:07:55.380000 This is very popular. 0:07:55.380000 --> 0:07:57.120000 For example, network modules. 0:07:57.120000 --> 0:08:00.000000 We see here a network module that has interfaces in it. 0:08:00.000000 --> 0:08:04.200000 And then that network module goes into an available module slot on a router 0:08:04.200000 --> 0:08:08.480000 or a switch. They could also be placed on smaller modules that we call 0:08:08.480000 --> 0:08:14.440000 WAN interface cards or Wix or port adapters. 0:08:14.440000 --> 0:08:16.740000 Or voice Wix, V-Wix. 0:08:16.740000 --> 0:08:19.280000 So interfaces can be in a wide variety of places. 0:08:19.280000 --> 0:08:21.680000 Sometimes all the interfaces are on one side. 0:08:21.680000 --> 0:08:24.740000 Like for example, this router that we're looking at here, all the interfaces 0:08:24.740000 --> 0:08:25.800000 are on this one side. 0:08:25.800000 --> 0:08:29.600000 If you turn this router around, you might see some LEDs blinking on the 0:08:29.600000 --> 0:08:33.000000 other side where there wouldn't be any place to physically plug in a cable 0:08:33.000000 --> 0:08:36.980000 anywhere. Other types of routers and switches might have interfaces on 0:08:36.980000 --> 0:08:39.000000 both sides for different purposes. 0:08:39.000000 --> 0:08:42.820000 So make sure you're aware of what model you're looking at because the 0:08:42.820000 --> 0:08:46.840000 interface might be on the other side of the chassis than what you expected 0:08:46.840000 --> 0:08:51.340000 it to be. Now how can we identify interfaces? 0:08:51.340000 --> 0:08:52.860000 Well, there's several different ways. 0:08:52.860000 --> 0:08:55.120000 Number one, visually, of course. 0:08:55.120000 --> 0:08:58.960000 If you have the luxury of being right there in front of the router or 0:08:58.960000 --> 0:09:01.780000 the switch, you can certainly look at it. 0:09:01.780000 --> 0:09:06.680000 And if you know in advance what the interface is supposed to look like, 0:09:06.680000 --> 0:09:10.360000 that can help you find it on the router switch. 0:09:10.360000 --> 0:09:14.580000 Or conversely, you can rule out what it definitely won't look like. 0:09:14.580000 --> 0:09:17.900000 For example, once you know that you're looking for an Ethernet interface, 0:09:17.900000 --> 0:09:21.440000 well, if you see a router that has a whole bunch of serial interfaces, 0:09:21.440000 --> 0:09:24.040000 you can say, look, I know those are serial interfaces. 0:09:24.040000 --> 0:09:28.280000 I might not know specifically what kind of connector is connecting to 0:09:28.280000 --> 0:09:31.720000 those serial interfaces, but just by looking at them, I can tell with 0:09:31.720000 --> 0:09:36.540000 my eyeballs, those are not Ethernet interfaces, and that's what I'm looking 0:09:36.540000 --> 0:09:38.340000 for, is an Ethernet interface. 0:09:38.340000 --> 0:09:43.460000 Certainly also, all Cisco modules have the printed part number on the 0:09:43.460000 --> 0:09:47.320000 module itself. Now depending on how old the module is or how beat up it 0:09:47.320000 --> 0:09:51.300000 is, that part number might be scratched off or smudged or something. 0:09:51.300000 --> 0:09:54.980000 So you can't always rely on the fact that it might have a very clearly 0:09:54.980000 --> 0:09:58.440000 visible part number, but hopefully it will. 0:09:58.440000 --> 0:10:01.600000 Also, platform numbering conventions. 0:10:01.600000 --> 0:10:05.800000 For example, if somebody says, hey, you need to take out the module that 0:10:05.800000 --> 0:10:10.180000 contains the fast Ethernet interface, zero slash five slash zero. 0:10:10.180000 --> 0:10:15.700000 Well, if you go to a device, it might have a whole slew of modules, all 0:10:15.700000 --> 0:10:18.160000 of which have fast Ethernet interfaces. 0:10:18.160000 --> 0:10:22.980000 So in this particular case, you have to know what zero slash five slash 0:10:22.980000 --> 0:10:27.880000 zero actually means, so you can identify the particular port or module 0:10:27.880000 --> 0:10:31.960000 that contains that interface you're looking for. 0:10:31.960000 --> 0:10:35.280000 And then of course, you have to understand Cisco part numbers as well. 0:10:35.280000 --> 0:10:38.320000 Somebody could say, for example, in that first objective we had, actually 0:10:38.320000 --> 0:10:41.060000 I think it was the second objective, the second objective said, hey, look 0:10:41.060000 --> 0:10:46.820000 for a PA-4T, we need you to replace that and swap it out for a replacement. 0:10:46.820000 --> 0:10:52.080000 Well, if you don't know what a PA-4T is and you're looking at a row that's 0:10:52.080000 --> 0:10:56.320000 got six or eight or ten modules in it, how would you know which one to 0:10:56.320000 --> 0:11:00.200000 pull out? So that would be a skill set that a CCT would need to have, 0:11:00.200000 --> 0:11:03.740000 is to be able to figure out what that module is, so they pull out the 0:11:03.740000 --> 0:11:07.820000 correct one. So let's look at some common interface types that you're 0:11:07.820000 --> 0:11:11.120000 going to see, so you might be able to recognize these, as well as identify 0:11:11.120000 --> 0:11:13.540000 them within the CCT exam itself. 0:11:13.540000 --> 0:11:16.440000 So we'll start with probably one of the most popular ones, which is the 0:11:16.440000 --> 0:11:22.160000 RJ45. So RJ45, RJ just stands for Register Jack. 0:11:22.160000 --> 0:11:25.300000 And you can see here, you've probably seen this a lot, this is typically 0:11:25.300000 --> 0:11:29.180000 used in Ethernet interfaces. 0:11:29.180000 --> 0:11:33.040000 For example, we see here a switch with a whole bunch of Ethernet interfaces, 0:11:33.040000 --> 0:11:39.560000 but please be careful, because RJ45 is not always used for Ethernet, don't 0:11:39.560000 --> 0:11:44.900000 assume that an RJ45 connector that you're looking at is supposed to connect 0:11:44.900000 --> 0:11:45.620000 to an Ethernet cable. 0:11:45.620000 --> 0:11:49.560000 For example, here's an RJ45 port that's connecting to a completely different 0:11:49.560000 --> 0:11:56.020000 protocol that uses completely different power requirements called HDSL. 0:11:56.020000 --> 0:11:59.540000 Here's another RJ45 jack that in this case is connecting to a console 0:11:59.540000 --> 0:12:02.080000 port or an auxiliary port. 0:12:02.080000 --> 0:12:07.040000 Once again, the cables and the jacks look the same, but the power requirements 0:12:07.040000 --> 0:12:11.180000 and what those interfaces are trying to accomplish is very different from 0:12:11.180000 --> 0:12:15.740000 each other. So the takeaway here is you should recognize what an RJ45 0:12:15.740000 --> 0:12:21.140000 jack looks like, but don't assume the type of protocol that is running 0:12:21.140000 --> 0:12:25.780000 across that cable, just based on the jack itself. 0:12:25.780000 --> 0:12:29.880000 Another type of common connector is called a G-BIC or a Gigabit Interface 0:12:29.880000 --> 0:12:35.220000 connector. These were initially designed to allow for fiber optic connections. 0:12:35.220000 --> 0:12:39.240000 Nowadays, G-BIC support a wide variety of combinations that are also used 0:12:39.240000 --> 0:12:41.920000 in WAN interfaces as well as Ethernet. 0:12:41.920000 --> 0:12:47.040000 So for example, the G-BIC is in the upper left here, and the G-BIC itself 0:12:47.040000 --> 0:12:49.080000 would go into an available slot. 0:12:49.080000 --> 0:12:53.700000 So for example, here we see a line card that's designed just for a variety 0:12:53.700000 --> 0:12:57.520000 of G-BICs. It looks like we've got about 16 or so G-BICs that will fit 0:12:57.520000 --> 0:12:59.220000 into this line card here. 0:12:59.220000 --> 0:13:04.740000 Down here we have a switch that is comprised mostly of RJ45 jacks, but 0:13:04.740000 --> 0:13:09.220000 it has a couple of up links in which you can put in some G-BICs. 0:13:09.220000 --> 0:13:13.620000 So a G-BIC would go into that type of slot right there. 0:13:13.620000 --> 0:13:17.660000 So historically G-BICs came out after RJ45. 0:13:17.660000 --> 0:13:23.000000 RJ45 was used for a long time, and then when fiber optic Ethernet came 0:13:23.000000 --> 0:13:27.620000 out, there were several variants or flavors of fiber optic Ethernet, and 0:13:27.620000 --> 0:13:31.140000 I'll get into that when we get into the cabling section next. 0:13:31.140000 --> 0:13:34.340000 There was some fiber optic Ethernet that was designed for short distances, 0:13:34.340000 --> 0:13:38.800000 medium, long distances, some fiber optic Ethernet that was designed where 0:13:38.800000 --> 0:13:43.300000 the light was supposed to be conveyed via simple and inexpensive LEDs, 0:13:43.300000 --> 0:13:49.180000 light emitting diodes, or very high quality expensive lasers would emit 0:13:49.180000 --> 0:13:51.300000 the light source. 0:13:51.300000 --> 0:13:54.940000 So somebody had the bright idea, hey, why don't we create these removable 0:13:54.940000 --> 0:14:00.680000 connectors called G-BICs, and then a person can just buy a module or router 0:14:00.680000 --> 0:14:04.560000 or switch that has an empty slot, and they can put in the G-BIC for whatever 0:14:04.560000 --> 0:14:08.560000 they want. If they want to support the high powered laser, they can put 0:14:08.560000 --> 0:14:10.200000 in a G-BIC that supports that. 0:14:10.200000 --> 0:14:13.980000 If they want to interface as the lower powered LEDs, they can put in a 0:14:13.980000 --> 0:14:15.640000 G-BIC that supports that. 0:14:15.640000 --> 0:14:17.600000 Now let's move forward in time. 0:14:17.600000 --> 0:14:22.120000 Eventually somebody said, well, these G-BICs are fairly wide, and there's 0:14:22.120000 --> 0:14:25.960000 only a certain amount of them that will fit onto a chassis. 0:14:25.960000 --> 0:14:29.480000 Wouldn't it be nice if we could create another type of adapter that's 0:14:29.480000 --> 0:14:32.880000 also removable that you can swap with different things that will always 0:14:32.880000 --> 0:14:39.060000 fit into a common slot or a common port on your router or switch, but 0:14:39.060000 --> 0:14:42.660000 it's smaller, so you could fit more of them into your device. 0:14:42.660000 --> 0:14:46.260000 And this is where something called the SFP came into play, which is a 0:14:46.260000 --> 0:14:49.400000 small form factor pluggable. 0:14:49.400000 --> 0:14:54.580000 So here we can see an example of an SFP that supports two fiber optic 0:14:54.580000 --> 0:14:58.820000 cables. So one of the cables would be for your transmitting light that 0:14:58.820000 --> 0:15:02.920000 you're transmitting out, another cable B for receiving incoming light 0:15:02.920000 --> 0:15:08.780000 pulses. And then that SFP would stick into an available slot. 0:15:08.780000 --> 0:15:14.120000 And because SFPs are smaller in nature, there's more SFP ports you can 0:15:14.120000 --> 0:15:19.620000 put into the same space as you would put in G-BICs. 0:15:19.620000 --> 0:15:26.140000 Now switches in addition to having RJ45 and or G-BICs or SFPs may also 0:15:26.140000 --> 0:15:28.920000 have some other special purpose interfaces. 0:15:28.920000 --> 0:15:32.240000 You need to be aware of these and be able to identify these as well. 0:15:32.240000 --> 0:15:36.780000 For example, the interface we see here is what's called an RPS interface. 0:15:36.780000 --> 0:15:40.020000 This stands for redundant power supply. 0:15:40.020000 --> 0:15:43.660000 We know that these switches have internal power supplies built into them, 0:15:43.660000 --> 0:15:46.900000 and your power cable would go right here into your power jack. 0:15:46.900000 --> 0:15:51.060000 But what happens if your internal power supply fails? 0:15:51.060000 --> 0:15:55.200000 It does happen. Well, this is where having your redundant power supply 0:15:55.200000 --> 0:15:56.240000 would come into play. 0:15:56.240000 --> 0:16:00.400000 So if you have a switch that's got an RPS interface, you can connect that 0:16:00.400000 --> 0:16:04.960000 to a special cable, and the other end of that cable will connect into 0:16:04.960000 --> 0:16:09.960000 an redundant power supply like an RPS 2300. 0:16:09.960000 --> 0:16:15.400000 The RPS 2300 here is an example of a single device that can monitor the 0:16:15.400000 --> 0:16:18.760000 power state of up to six switches. 0:16:18.760000 --> 0:16:22.960000 And if up to two of those switches fail, if the internal power supply 0:16:22.960000 --> 0:16:28.100000 fails, this guy here on the right can provide power, keep those switches 0:16:28.100000 --> 0:16:32.500000 going, so you don't have a power outage right in the middle of a busy 0:16:32.500000 --> 0:16:37.960000 workday. Another type of special purpose interface is called a stacking 0:16:37.960000 --> 0:16:43.800000 interface. So here we have an example of a cup of a 3750, and if you buy 0:16:43.800000 --> 0:16:48.460000 a certain stack cable and connect it to those stack interfaces, you can 0:16:48.460000 --> 0:16:52.720000 then have what's called a switch stack, where you have multiple 3750s, 0:16:52.720000 --> 0:16:58.900000 cable together, and they operate and can be managed as one single unit. 0:16:58.900000 --> 0:17:02.220000 So this is by using certain type of interface called a stack interface, 0:17:02.220000 --> 0:17:06.820000 which connects the back plane of these devices together. 0:17:06.820000 --> 0:17:10.260000 Now other types of switches also have stack interfaces that look a little 0:17:10.260000 --> 0:17:12.800000 bit differently and use different cables. 0:17:12.800000 --> 0:17:17.580000 For example, here's the 2960, the KEL is 2960 uses a special module called 0:17:17.580000 --> 0:17:19.520000 a flex stack module. 0:17:19.520000 --> 0:17:23.960000 The purpose is the same as what we just saw in the 3750, but the cable 0:17:23.960000 --> 0:17:25.580000 it uses is different. 0:17:25.580000 --> 0:17:29.480000 You can see right there it's got completely different ends or tips to 0:17:29.480000 --> 0:17:32.560000 it, and those connectors do the same purpose. 0:17:32.560000 --> 0:17:36.240000 You can stack several 2960s together. 0:17:36.240000 --> 0:17:42.180000 So that takes care of our LAN interfaces, our RJ45s, our fiber optic interfaces 0:17:42.180000 --> 0:17:47.340000 of our like G-Bix and SFPs, as well as some special purpose switch interfaces 0:17:47.340000 --> 0:17:52.240000 for stacking. Now let's take a look at our LAN interfaces, our serial 0:17:52.240000 --> 0:17:56.680000 interfaces. So first of all, why do we need a serial interface? 0:17:56.680000 --> 0:17:59.600000 Well, what does serial mean? 0:17:59.600000 --> 0:18:03.660000 In the context of data communication, serial simply means I'm putting 0:18:03.660000 --> 0:18:07.060000 one bit after the other onto the wire. 0:18:07.060000 --> 0:18:11.840000 So if I want to transmit a bunch of bits to you, I send you one at a time. 0:18:11.840000 --> 0:18:15.720000 That is simply what we mean by serial communications. 0:18:15.720000 --> 0:18:25.920000 Now if we think about that, Ethernet also does serial communications, 0:18:25.920000 --> 0:18:28.120000 right? So as we look at our RJ45 jack, there's several pins there on the 0:18:28.120000 --> 0:18:33.020000 RJ45 jack. Ethernet at minimum needs four of those pins, two for transmitting 0:18:33.020000 --> 0:18:35.120000 and two for receiving. 0:18:35.120000 --> 0:18:37.800000 But let's just focus in, for example, on the two pins are transmitting 0:18:37.800000 --> 0:18:39.780000 on your RJ45 jack. 0:18:39.780000 --> 0:18:44.780000 One of those pins is for a high voltage, one of those pins is for a lower 0:18:44.780000 --> 0:18:47.880000 voltage. So when you're transmitting a one, you'll use one pin, when you're 0:18:47.880000 --> 0:18:53.240000 transmitting a zero, you'll use another pin, but still one bit after the 0:18:53.240000 --> 0:18:57.560000 other. So why do we need these special types of cables and interfaces 0:18:57.560000 --> 0:19:03.600000 called serial, which also transmit electricity in bits one bit after the 0:19:03.600000 --> 0:19:05.420000 other in serial communication? 0:19:05.420000 --> 0:19:08.160000 Well, here's the main distinction, the main differentiator. 0:19:08.160000 --> 0:19:14.420000 Historically, Ethernet capped out at a maximum distance of about 100 meters. 0:19:14.420000 --> 0:19:17.840000 So the maximum distance you could have between any two endpoints of your 0:19:17.840000 --> 0:19:20.020000 Ethernet cable was 100 meters. 0:19:20.020000 --> 0:19:24.400000 So what if you wanted a single line to run a protocol that was longer 0:19:24.400000 --> 0:19:26.260000 than this in distance? 0:19:26.260000 --> 0:19:29.180000 Well, then you needed something other than Ethernet. 0:19:29.180000 --> 0:19:32.800000 Ethernet wouldn't handle that if I wanted to transmit my electricity maybe 0:19:32.800000 --> 0:19:36.820000 500 meters or maybe a thousand meters or maybe even five or ten miles 0:19:36.820000 --> 0:19:39.280000 from one interface to the other. 0:19:39.280000 --> 0:19:44.540000 This is where WAN protocols or wide area networking came into play. 0:19:44.540000 --> 0:19:48.360000 So serial interfaces came out in that day. 0:19:48.360000 --> 0:19:52.180000 It's used typically for WAN connectivity when protocols other than Ethernet 0:19:52.180000 --> 0:19:57.500000 are needed. And serial interfaces are primarily designed for time division 0:19:57.500000 --> 0:20:01.260000 multiplexing. What is that? 0:20:01.260000 --> 0:20:02.900000 Well, think about Ethernet. 0:20:02.900000 --> 0:20:05.420000 Once again, if you're working in the field of networking, you have to 0:20:05.420000 --> 0:20:09.300000 know what Ethernet is and how Ethernet works. 0:20:09.300000 --> 0:20:12.880000 Historically, the way Ethernet works is that you can have a whole bunch 0:20:12.880000 --> 0:20:18.240000 of devices all sharing a common Ethernet cable, which means that only 0:20:18.240000 --> 0:20:21.360000 one device can talk at a time. 0:20:21.360000 --> 0:20:23.980000 That's one of the cardinal rules of Ethernet. 0:20:23.980000 --> 0:20:27.220000 If we're all sharing the same Ethernet cable, that means when I'm talking, 0:20:27.220000 --> 0:20:31.100000 that means I am sending out electrical energy on that cable, nobody else 0:20:31.100000 --> 0:20:32.480000 can talk but me. 0:20:32.480000 --> 0:20:36.120000 And then when I'm done, somebody else can talk. 0:20:36.120000 --> 0:20:39.740000 So in theory, every device can talk. 0:20:39.740000 --> 0:20:42.240000 They'll have some opportunity to talk. 0:20:42.240000 --> 0:20:47.640000 But if I have one device that's more chatty than others, that device is 0:20:47.640000 --> 0:20:50.100000 going to get that cable more frequently. 0:20:50.100000 --> 0:20:54.140000 So every other device is not going to get a fair share of the bandwidth 0:20:54.140000 --> 0:20:58.800000 because that one device that's chatty is getting to speak more frequently. 0:20:58.800000 --> 0:21:02.440000 Time division multiplexing is one way around that. 0:21:02.440000 --> 0:21:06.380000 Time division multiplexing says, look, we still have a situation where 0:21:06.380000 --> 0:21:11.680000 we have one physical media, in this case, a serial cable, a serial link, 0:21:11.680000 --> 0:21:14.180000 and the serial link is able to carry bits. 0:21:14.180000 --> 0:21:18.580000 Some of those bits are from Tom, some are from Sue, some are from Sally. 0:21:18.580000 --> 0:21:21.800000 But unlike Ethernet, they would say, hey, Tom, if you're really chatty, 0:21:21.800000 --> 0:21:25.360000 if you're talking right now, most of the bits going across a serial cable 0:21:25.360000 --> 0:21:26.820000 will be from you. 0:21:26.820000 --> 0:21:30.900000 Time division multiplexing says, hey, look, we're going to take each user 0:21:30.900000 --> 0:21:35.720000 that's connected to this cable and give them a certain dedicated slot 0:21:35.720000 --> 0:21:42.100000 of time. In other words, during one second, the first quarter, the first 0:21:42.100000 --> 0:21:46.040000 25% of every single second will be for Tom. 0:21:46.040000 --> 0:21:49.980000 The second quarter of every single second will be for Sally. 0:21:49.980000 --> 0:21:51.660000 The third quarter will be for Sue. 0:21:51.660000 --> 0:21:57.880000 So that way, whether Tom is talking or not, he only has access to his 0:21:57.880000 --> 0:22:00.460000 particular time slot and that's it. 0:22:00.460000 --> 0:22:06.060000 Everybody has a reserve time slot, so we know when data is going to fit 0:22:06.060000 --> 0:22:07.920000 into those time slots. 0:22:07.920000 --> 0:22:12.320000 So serial cables were primarily designed for those protocols that understood 0:22:12.320000 --> 0:22:15.240000 time division multiplexing. 0:22:15.240000 --> 0:22:19.080000 Now, serial cables provide for lots of different form factors. 0:22:19.080000 --> 0:22:22.480000 If I just say, hey, locate the serial cable on my router and pull it out, 0:22:22.480000 --> 0:22:25.320000 that's not going to give you enough information because there's a lot 0:22:25.320000 --> 0:22:27.260000 of different serial connectors. 0:22:27.260000 --> 0:22:30.940000 Let me show you three of the most common form factors that you'll find 0:22:30.940000 --> 0:22:35.840000 on Cisco devices if you're asked to identify a serial connector. 0:22:35.840000 --> 0:22:41.080000 By far, the most common form factor is what's called the DB60 or 5-in 0:22:41.080000 --> 0:22:43.660000 -1, and this is what it looks like right here. 0:22:43.660000 --> 0:22:48.880000 So this is what most serial cables are plugged into, is a DB60 jack. 0:22:48.880000 --> 0:22:51.980000 Another kind is called a 68-pin connector. 0:22:51.980000 --> 0:22:54.260000 You can see it's narrower, but it's longer. 0:22:54.260000 --> 0:22:59.020000 Another kind is called a Cisco smart serial, completely different form 0:22:59.020000 --> 0:23:01.700000 factor that connects to a completely different cable. 0:23:01.700000 --> 0:23:07.560000 So all three of these are technically what we call serial interfaces, 0:23:07.560000 --> 0:23:10.560000 but you can see their form factors are vastly different. 0:23:10.560000 --> 0:23:13.860000 And there's even more than this, but these are the three most common that 0:23:13.860000 --> 0:23:16.720000 you'll find on Cisco devices. 0:23:16.720000 --> 0:23:22.560000 Now, in addition to Ethernet interfaces and serial interfaces, there are 0:23:22.560000 --> 0:23:26.100000 some other specialized interfaces I just want to call your attention to. 0:23:26.100000 --> 0:23:27.960000 Take a look at these. 0:23:27.960000 --> 0:23:30.260000 These are RJ45 jacks. 0:23:30.260000 --> 0:23:32.420000 You might initially think, oh, that's Ethernet. 0:23:32.420000 --> 0:23:37.120000 Not so quick. These interfaces are specifically for voice communications. 0:23:37.120000 --> 0:23:41.000000 Notice that one of them is located on what's called an FXX interface. 0:23:41.000000 --> 0:23:45.060000 The other's got an FXO interface. 0:23:45.060000 --> 0:23:50.540000 FXX ports connect directly to regular analog phones. 0:23:50.540000 --> 0:23:53.320000 So, you know, if you've got a regular analog phone that you've got plugged 0:23:53.320000 --> 0:23:56.440000 into your wall and you pick up that phone and you'd die to your mom or 0:23:56.440000 --> 0:24:02.000000 your boss, it would plug directly into an FXS interface. 0:24:02.000000 --> 0:24:07.540000 FXO ports are used to connect to PBX or key systems to provide off-premises 0:24:07.540000 --> 0:24:12.080000 connections to the public switched telephone network. 0:24:12.080000 --> 0:24:16.900000 And then lastly, some other interfaces are coaxial interfaces. 0:24:16.900000 --> 0:24:19.840000 There's a lot of protocols that make use of coaxial interfaces, just like 0:24:19.840000 --> 0:24:24.320000 the coaxial cable you have going into your cable TV set at home. 0:24:24.320000 --> 0:24:29.380000 For example, we see the on the Cisco 7300, the 6 port clear channel T3 0:24:29.380000 --> 0:24:35.860000 line card on the left, and we have the 1 port ATM DS3 port adapter on 0:24:35.860000 --> 0:24:40.060000 the right. Now, at the CCT level, you don't need to know what some of 0:24:40.060000 --> 0:24:44.300000 these more advanced terms like T3 and A3 are for ATM. 0:24:44.300000 --> 0:24:53.860000 You don't need to know that. 0:24:53.860000 --> 0:24:58.220000 The module you might be asked to replace or look for might have coaxial 0:24:58.220000 --> 0:24:59.960000 cable interfaces. 0:24:59.960000 --> 0:25:05.000000 And you can see here on just the 7200 series, there are lots of different 0:25:05.000000 --> 0:25:09.540000 modules, lots of different interfaces that carry different things. 0:25:09.540000 --> 0:25:11.100000 So, let's go back to our first objective. 0:25:11.100000 --> 0:25:15.860000 Our first question was you need to swap out a faulty PA4T on your Cisco 0:25:15.860000 --> 0:25:20.060000 router. Given the image below, which of these letters identifies a correct 0:25:20.060000 --> 0:25:21.740000 port adapter that needs to be replaced? 0:25:21.740000 --> 0:25:25.000000 So, the first thing you would need to do to answer this question is you 0:25:25.000000 --> 0:25:28.780000 would probably want to Google the term PA-4T. 0:25:28.780000 --> 0:25:32.440000 So, let's go ahead and do that. 0:25:32.440000 --> 0:25:37.200000 All right, so I'm going to go ahead and Google PA-4T here. 0:25:37.200000 --> 0:25:40.300000 Let's just bring this over here so we can see it. 0:25:40.300000 --> 0:25:48.600000 I'll say Cisco PA-4T. 0:25:48.600000 --> 0:25:52.000000 Now, we can see right here, right away we can see, ah, this is clearly 0:25:52.000000 --> 0:25:54.000000 a serial adapter. 0:25:54.000000 --> 0:25:55.840000 This is a serial port. 0:25:55.840000 --> 0:25:57.820000 So, right there, what do we know? 0:25:57.820000 --> 0:26:03.480000 We know that serial interfaces never come in the form factor of an RJ45. 0:26:03.480000 --> 0:26:06.580000 So, if I'm looking at my device, once again, let's go back to our picture 0:26:06.580000 --> 0:26:12.840000 right here. Most of the interfaces on this router are RJ45 interfaces, 0:26:12.840000 --> 0:26:15.780000 and that is not what I'm looking for. 0:26:15.780000 --> 0:26:19.480000 So, we can rule out a lot of this stuff. 0:26:19.480000 --> 0:26:23.800000 So, we know that the RJ45s are definitely out of the equation, so we're 0:26:23.800000 --> 0:26:25.780000 looking for serial ports. 0:26:25.780000 --> 0:26:29.980000 Now, if we continue to go back here, probably the most important thing 0:26:29.980000 --> 0:26:31.940000 to do would just be to click on images. 0:26:31.940000 --> 0:26:35.440000 Let's get an image of what a PA-4T looks like. 0:26:35.440000 --> 0:26:37.380000 And here we can see. 0:26:37.380000 --> 0:26:42.300000 It has four interfaces on it, which are those special DB60s. 0:26:42.300000 --> 0:26:48.100000 So, based on that, the correct answer would be A. 0:26:48.100000 --> 0:26:52.840000 A here would be the PA-4T that you would need to swap out. 0:26:52.840000 --> 0:26:56.860000 Okay, what about answering this question? 0:26:56.860000 --> 0:26:59.380000 Port numbering conventions. 0:26:59.380000 --> 0:27:04.660000 So, how do I find out if, for example, I'm asked to replace, if someone 0:27:04.660000 --> 0:27:08.700000 says, hey, look, we're having a problem with port 0 slash 7 slash 5. 0:27:08.700000 --> 0:27:11.020000 Can you take a look at it for us? 0:27:11.020000 --> 0:27:17.320000 Well, how would I know where on my router is port 0 slash 7 slash 5? 0:27:17.320000 --> 0:27:20.660000 Because every router has a different numbering convention, it seems. 0:27:20.660000 --> 0:27:24.880000 So, step number one would be to identify the chassis or model that you're 0:27:24.880000 --> 0:27:29.400000 looking at. Somewhere on the chassis, there should be a stamp or a sticker 0:27:29.400000 --> 0:27:34.500000 or label that indicates what specific kind of router or switch this is 0:27:34.500000 --> 0:27:35.760000 that you're looking at. 0:27:35.760000 --> 0:27:39.920000 For example, this is an example of a Cisco 7206 that we're looking at 0:27:39.920000 --> 0:27:45.220000 right here. Once you've identified that, then locate the hardware installation 0:27:45.220000 --> 0:27:47.840000 guide on Cisco.com. 0:27:47.840000 --> 0:27:49.960000 I like to use Google once again. 0:27:49.960000 --> 0:27:53.020000 For example, if I can go back to here. 0:27:53.020000 --> 0:28:03.280000 If I say, okay, now I know it's a Cisco 7206, Cisco 7206 Hardware Installation 0:28:03.280000 --> 0:28:08.180000 Guide. And there we go, installation and configuration guide. 0:28:08.180000 --> 0:28:10.460000 That's probably what you're going to be looking for. 0:28:10.460000 --> 0:28:16.000000 So once you find that, then open up that guide and do a quick search on 0:28:16.000000 --> 0:28:18.100000 the keyword of numbering. 0:28:18.100000 --> 0:28:20.660000 And that will bring you to some sort of diagram like this one. 0:28:20.660000 --> 0:28:24.000000 This actually came from the hardware installation guide of the 7206. 0:28:24.000000 --> 0:28:28.000000 And it shows us, ah, okay, on this platform, the module on the very bottom 0:28:28.000000 --> 0:28:30.220000 is port adapter slot 0. 0:28:30.220000 --> 0:28:35.300000 And then we have 1, 2, 3, 4, 5 and 6. 0:28:35.300000 --> 0:28:40.060000 So based on that, going to our second objective, was we needed swap out 0:28:40.060000 --> 0:28:45.420000 the port adapter that contained controller T30 slash 2 slash 0. 0:28:45.420000 --> 0:28:49.940000 Well, once we've identified this as a 7206, we know that this bottom module 0:28:49.940000 --> 0:28:53.400000 is, and we know if we look at the hardware installation guide, we know 0:28:53.400000 --> 0:28:57.760000 that the number in the middle here, in this case the 2, references the 0:28:57.760000 --> 0:29:03.220000 slot number where the module or the port adapter is sitting in or is seated. 0:29:03.220000 --> 0:29:06.900000 So if we're looking for the module that's in slot 2, well, now we know 0:29:06.900000 --> 0:29:09.160000 that this bottom slot is slot 0. 0:29:09.160000 --> 0:29:14.620000 The one on the left is slot 1, so slot 2 is answer G. 0:29:14.620000 --> 0:29:18.900000 So even though we might not know what that port adapter is or what's designed 0:29:18.900000 --> 0:29:25.600000 to do, just the fact that 0 slash 2 slash 0, the 2 identifies that G is 0:29:25.600000 --> 0:29:26.640000 the correct answer.