WEBVTT 0:00:03.160000 --> 0:00:08.300000 Hello and welcome to this section on basic switching review and configuration. 0:00:08.300000 --> 0:00:12.040000 So let's just do a real quick review on the basics of how layer two switches 0:00:12.040000 --> 0:00:19.280000 work. So number one, we know the switch is essentially a multi port bridge. 0:00:19.280000 --> 0:00:20.400000 What does that mean? 0:00:20.400000 --> 0:00:25.160000 That means that its primary job is to take in ethernet frames and to look 0:00:25.160000 --> 0:00:29.380000 at the source and destination MAC address of those frames and treat the 0:00:29.380000 --> 0:00:32.560000 frames accordingly based on what it sees. 0:00:32.560000 --> 0:00:33.460000 So what does that mean? 0:00:33.460000 --> 0:00:37.760000 Well, it means that number one, we forward the frames based on the MAC 0:00:37.760000 --> 0:00:40.520000 address table. How's the MAC address table there? 0:00:40.520000 --> 0:00:42.080000 How's it built? What's it used for? 0:00:42.080000 --> 0:00:43.820000 Well, once again, a quick review. 0:00:43.820000 --> 0:00:49.320000 We know that every device in a typical switched environment, every device 0:00:49.320000 --> 0:00:50.600000 has a unique switch port. 0:00:50.600000 --> 0:00:55.000000 In other words, my laptop is directly connected via a cable to its own 0:00:55.000000 --> 0:00:59.480000 switch port. The laptop next to me, the printer next to me, the fax machine 0:00:59.480000 --> 0:01:03.940000 next to me, they all have their dedicated cables connecting in to dedicated 0:01:03.940000 --> 0:01:08.080000 switch ports. Of course, we're assuming a wired network right here. 0:01:08.080000 --> 0:01:15.120000 So assuming that, then we know that the moment that a device sends an 0:01:15.120000 --> 0:01:18.800000 ethernet frame, the source MAC address of that ethernet frame will be 0:01:18.800000 --> 0:01:19.560000 learned by the switch. 0:01:19.560000 --> 0:01:22.720000 The switch will see that MAC address frame as it comes in, it'll go into 0:01:22.720000 --> 0:01:25.500000 its MAC address table and say, oh, I've never seen this MAC address frame 0:01:25.500000 --> 0:01:27.320000 before. This is brand new. 0:01:27.320000 --> 0:01:32.040000 And so take the MAC address, the port that it came in on, and the VLAN 0:01:32.040000 --> 0:01:36.520000 that port is associated to and learn that into the MAC address table. 0:01:36.520000 --> 0:01:40.100000 And then that entry will stay in the MAC address table for a variety of 0:01:40.100000 --> 0:01:44.140000 reasons. Number one, if that MAC address is active, if it's pretty periodically 0:01:44.140000 --> 0:01:48.240000 sending stuff, that entry will stay in the MAC address table. 0:01:48.240000 --> 0:01:53.960000 If that MAC address goes dormant or silent, like let's say that my laptop 0:01:53.960000 --> 0:01:59.100000 just was connected to the switch, but didn't send anything, just was completely 0:01:59.100000 --> 0:02:01.140000 idle and didn't send anything. 0:02:01.140000 --> 0:02:04.080000 Well, then that MAC address would eventually age out of the MAC address 0:02:04.080000 --> 0:02:08.720000 table. And you should remember that that's for five minutes or 300 seconds. 0:02:08.720000 --> 0:02:13.500000 So 300 seconds is the inactivity or the aging timer of MAC addresses in 0:02:13.500000 --> 0:02:14.840000 the MAC address table. 0:02:14.840000 --> 0:02:17.320000 Thirdly, if the port goes down. 0:02:17.320000 --> 0:02:22.280000 So if I disconnect my laptop and move away, once that port detects it's 0:02:22.280000 --> 0:02:26.840000 electrically not connected to anything anymore, then any and all MAC addresses 0:02:26.840000 --> 0:02:30.480000 that were associated to that port are wiped out of the MAC address table. 0:02:30.480000 --> 0:02:32.100000 So that's the learning process. 0:02:32.100000 --> 0:02:33.860000 The forwarding process is very similar. 0:02:33.860000 --> 0:02:36.760000 An Ethernet frame comes in and now the switch looks at the destination 0:02:36.760000 --> 0:02:40.520000 MAC address. Looks at that destination MAC address, goes into the MAC 0:02:40.520000 --> 0:02:43.100000 address table, tries to find a corresponding hit. 0:02:43.100000 --> 0:02:46.740000 If it does find a match, then let's forward that Ethernet frame out the 0:02:46.740000 --> 0:02:48.740000 port where it needs to go. 0:02:48.740000 --> 0:02:52.520000 If it doesn't find a match, then that frame will be flooded and be flooded 0:02:52.520000 --> 0:02:57.340000 out. All other ports are in the same VLAN as the ingress port. 0:02:57.340000 --> 0:03:02.000000 We know that switches separate collision domains. 0:03:02.000000 --> 0:03:05.640000 Once again, this is a review of what that's talking about. 0:03:05.640000 --> 0:03:07.260000 That means that. 0:03:07.260000 --> 0:03:15.840000 I could have something like this. 0:03:15.840000 --> 0:03:20.180000 And these two laptops laptop A and B. 0:03:20.180000 --> 0:03:25.420000 They could send frames at exactly the same time into that switch. 0:03:25.420000 --> 0:03:29.480000 And unlike a hub where this would be a problem and those frames would 0:03:29.480000 --> 0:03:33.520000 cause a collision and they'd have to be retransmitted in a switched environment. 0:03:33.520000 --> 0:03:36.980000 That's not the case because if you recall from some of my earlier courses, 0:03:36.980000 --> 0:03:40.500000 switches have memory associated to their interfaces. 0:03:40.500000 --> 0:03:44.500000 And so this memory can store and buffer these frames. 0:03:44.500000 --> 0:03:48.360000 So frames can be coming in multiple switch ports all simultaneously all 0:03:48.360000 --> 0:03:52.900000 day long and the switch will buffer those frames and then each one one 0:03:52.900000 --> 0:03:56.580000 by one will be looked up and sent out to where it needs to go. 0:03:56.580000 --> 0:04:02.360000 Now, normally your connection to a switch is in full duplex mode, which 0:04:02.360000 --> 0:04:06.240000 means that you can transmit at exactly the same time the switch is transmitting 0:04:06.240000 --> 0:04:10.600000 to you. Because if you remember the basics of ethernet cabling with an 0:04:10.600000 --> 0:04:19.140000 ethernet cable, we had something like this where your transmit, like if 0:04:19.140000 --> 0:04:22.760000 this was transmit on your side for transmitting ones and zeros, ended 0:04:22.760000 --> 0:04:28.080000 up being received on the other side of the cable and his transmit pin, 0:04:28.080000 --> 0:04:31.840000 his transmit wire was your receive. 0:04:31.840000 --> 0:04:35.620000 So you're actually using so if I'm transmitting this way and he's transmitting 0:04:35.620000 --> 0:04:41.100000 this way, we're actually using completely separate strands of copper cable 0:04:41.100000 --> 0:04:43.740000 inside our main ethernet cable. 0:04:43.740000 --> 0:04:45.540000 They're not going to run into each other. 0:04:45.540000 --> 0:04:51.680000 Now, in the unlikely event that one or both of these devices is configured 0:04:51.680000 --> 0:04:57.080000 for half duplex, well then they can't do this. 0:04:57.080000 --> 0:05:00.620000 In half duplex mode only one side can talk at a time. 0:05:00.620000 --> 0:05:04.060000 And if they did this, if the switch was transmitting to me at exactly 0:05:04.060000 --> 0:05:08.660000 the same time I was transmitting to him, that would be considered a collision. 0:05:08.660000 --> 0:05:12.340000 Now why they say that switch is separate collision domains is because 0:05:12.340000 --> 0:05:17.120000 if there's any collisions here, it does not affect PCB. 0:05:17.120000 --> 0:05:20.920000 PCB can still be transmitting all day long because his connection to the 0:05:20.920000 --> 0:05:25.000000 switch isn't a completely separate collision domain. 0:05:25.000000 --> 0:05:28.360000 So any collisions that happen here are completely independent from collisions 0:05:28.360000 --> 0:05:29.220000 that happen here. 0:05:29.220000 --> 0:05:33.540000 So each switch port, if collisions happen on it, which they shouldn't, 0:05:33.540000 --> 0:05:39.280000 will not affect any of the other ports on that same switch. 0:05:39.280000 --> 0:05:44.660000 And layer two switches operate at the data link layer. 0:05:44.660000 --> 0:05:48.160000 However, the reality is that most of the switches you can purchase these 0:05:48.160000 --> 0:05:51.900000 days are what we call multi-layer switches, which means they can not only 0:05:51.900000 --> 0:05:55.480000 look at MAC addresses to make their forwarding decisions, they can also 0:05:55.480000 --> 0:05:56.360000 look higher than that. 0:05:56.360000 --> 0:06:00.600000 They can look at the IP addresses, they can even look at TCP UDP port 0:06:00.600000 --> 0:06:03.520000 numbers to make forward or filtering decisions. 0:06:03.520000 --> 0:06:06.100000 That's what we mean by a multi-layer switch. 0:06:06.100000 --> 0:06:09.080000 All right, so let's just do a quick review here on some of the basics 0:06:09.080000 --> 0:06:11.180000 of configuring a switch. 0:06:11.180000 --> 0:06:15.940000 All right, so there's nothing new here. 0:06:15.940000 --> 0:06:20.140000 We've already talked about the MACRS table and basically how it works. 0:06:20.140000 --> 0:06:23.780000 So some initial configuration commands. 0:06:23.780000 --> 0:06:26.820000 You're probably going to want to put a host name on your switch, enable 0:06:26.820000 --> 0:06:30.080000 password. You might want to put some sort of banners to give some sort 0:06:30.080000 --> 0:06:33.680000 of descriptive warning like this switch belongs to engineering department. 0:06:33.680000 --> 0:06:38.000000 Keep out. Or if you have any problems on this switch, call Ken, the network 0:06:38.000000 --> 0:06:40.320000 admin or whatever it might happen to be. 0:06:40.320000 --> 0:06:43.460000 You're probably also going to want to type in no IP domain lookup and 0:06:43.460000 --> 0:06:47.080000 logging synchronous, which are not necessary, but certainly make your 0:06:47.080000 --> 0:06:51.100000 life a lot more convenient if you do that. 0:06:51.100000 --> 0:06:54.560000 And then of course you can do show IP interface brief because different 0:06:54.560000 --> 0:06:58.300000 switches have different naming conventions on their ports. 0:06:58.300000 --> 0:06:59.440000 What do I mean by that? 0:06:59.440000 --> 0:07:02.660000 Well, for example, some switches have 10, 100 interfaces. 0:07:02.660000 --> 0:07:05.980000 So their ports might start out as fast Ethernet something. 0:07:05.980000 --> 0:07:08.880000 A lot of other switches might just have gigabit Ethernet ports. 0:07:08.880000 --> 0:07:10.220000 So you'll need to know that. 0:07:10.220000 --> 0:07:12.560000 Or if I'm going to put an IP address on an interface, I have to know do 0:07:12.560000 --> 0:07:16.500000 I start out interface fast Ethernet something, interface gigabit Ethernet 0:07:16.500000 --> 0:07:18.000000 something, you know, what is it? 0:07:18.000000 --> 0:07:19.980000 Also the numbering convention. 0:07:19.980000 --> 0:07:24.620000 Some switches have a number, a slash, a number like gigabit zero slash 0:07:24.620000 --> 0:07:26.640000 one or something like that. 0:07:26.640000 --> 0:07:29.560000 Other switches, especially switches that you'll find that can stack together 0:07:29.560000 --> 0:07:31.000000 in a switching stack. 0:07:31.000000 --> 0:07:34.140000 A lot of times we'll have three digits in their interface numbering like 0:07:34.140000 --> 0:07:37.920000 gigabit zero slash zero slash one or something like that. 0:07:37.920000 --> 0:07:42.140000 So by doing show IP interface brief, you can very quickly learn how does 0:07:42.140000 --> 0:07:44.960000 this switch view its interfaces? 0:07:44.960000 --> 0:07:50.140000 How does it name its interfaces? 0:07:50.140000 --> 0:07:57.160000 Okay, so switch ports by default don't support IP addressing. 0:07:57.160000 --> 0:08:01.220000 They only support the forwarding of Ethernet frames. 0:08:01.220000 --> 0:08:06.540000 So if you want to put an IP address on your switch and you probably will 0:08:06.540000 --> 0:08:09.260000 see you can tell that to it so you can ping it. 0:08:09.260000 --> 0:08:13.520000 There's a couple of places that you can do that. 0:08:13.520000 --> 0:08:17.200000 Let me just show you real quickly here. 0:08:17.200000 --> 0:08:20.120000 So here's my switch. 0:08:20.120000 --> 0:08:24.780000 Here are a couple of ports on that switch. 0:08:24.780000 --> 0:08:29.120000 Let's say zero slash one zero slash two and so forth. 0:08:29.120000 --> 0:08:36.800000 Okay, so by default, if I try to put an IP address on any of those physical 0:08:36.800000 --> 0:08:39.120000 interfaces, it won't let me. 0:08:39.120000 --> 0:08:44.100000 So let's say that all these interfaces here were in one broadcast domain. 0:08:44.100000 --> 0:08:46.980000 Let's just say it was VLAN two. 0:08:46.980000 --> 0:08:51.160000 Okay, and as a network administrator, I decide that everything that was 0:08:51.160000 --> 0:08:54.460000 in that broadcast domain that was in VLAN two was going to be in the two 0:08:54.460000 --> 0:08:59.180000 dot two dot two dot zero slash twenty four network. 0:08:59.180000 --> 0:09:05.100000 All right. Well, if I want the devices in this VLAN to be able to access 0:09:05.100000 --> 0:09:09.940000 the switch, ping it, tell net to it, SSH to it, I need to give this switch 0:09:09.940000 --> 0:09:14.020000 an address in the two to two network so they can reach it. 0:09:14.020000 --> 0:09:15.860000 I need to give them a host address. 0:09:15.860000 --> 0:09:26.540000 So one way is I can create what's called a switched virtual interface. 0:09:26.540000 --> 0:09:32.140000 A logical interface cables don't plug into it. 0:09:32.140000 --> 0:09:34.760000 It's kind of like a, like our VTY lines, right? 0:09:34.760000 --> 0:09:37.140000 We were dealing with telnet or SSH. 0:09:37.140000 --> 0:09:39.160000 A VTY line is not a physical thing. 0:09:39.160000 --> 0:09:40.200000 You can't see it. 0:09:40.200000 --> 0:09:43.660000 If you're looking at a router switch, it's a placeholder for your SSH 0:09:43.660000 --> 0:09:46.340000 and telnet configuration commands. 0:09:46.340000 --> 0:09:50.780000 Well, switch virtual interface is similarly a logical interface. 0:09:50.780000 --> 0:09:53.280000 So we just say interface. 0:09:53.280000 --> 0:09:56.920000 So we have to go into global configuration mode first config T and then 0:09:56.920000 --> 0:10:02.340000 we say interface VLAN in this case VLAN two. 0:10:02.340000 --> 0:10:06.080000 I want to create a switched virtual interface for this particular VLAN. 0:10:06.080000 --> 0:10:10.820000 Then they'll drop you down into config dash IF mode interface mode. 0:10:10.820000 --> 0:10:13.260000 And here I can put my IP address. 0:10:13.260000 --> 0:10:17.600000 And of course, don't forget about your subnet mask. 0:10:17.600000 --> 0:10:25.100000 And don't forget to do your no shutdown command. 0:10:25.100000 --> 0:10:26.540000 So that's one place. 0:10:26.540000 --> 0:10:28.840000 You can place an IP address. 0:10:28.840000 --> 0:10:32.960000 And if your primary objective is, hey, I want this switch to have a host 0:10:32.960000 --> 0:10:35.440000 address in this broadcast domain. 0:10:35.440000 --> 0:10:37.240000 There's a broadcast domain. 0:10:37.240000 --> 0:10:39.940000 There's got a whole bunch of hosts in it and he needs an address as well. 0:10:39.940000 --> 0:10:42.460000 That's perfectly acceptable to do it that way. 0:10:42.460000 --> 0:10:49.840000 Another method you could do is we could change actually the physical interface 0:10:49.840000 --> 0:10:54.540000 to the point where it will allow us to put in an IP address. 0:10:54.540000 --> 0:11:01.860000 So for example, let's say that this interface right here was connecting 0:11:01.860000 --> 0:11:09.060000 to a server. And he was going to be three, three, three, one. 0:11:09.060000 --> 0:11:12.640000 Let's say slash 30. 0:11:12.640000 --> 0:11:20.100000 Okay. We want his default gateway to be three, three, three, two. 0:11:20.100000 --> 0:11:23.940000 That's the only other available address in that network. 0:11:23.940000 --> 0:11:25.860000 And we want that to be the switch. 0:11:25.860000 --> 0:11:27.520000 The switch is capable of routing. 0:11:27.520000 --> 0:11:29.360000 This is a multi-layer switch. 0:11:29.360000 --> 0:11:32.080000 So we want him to be the default gateway for this. 0:11:32.080000 --> 0:11:34.480000 The server here. 0:11:34.480000 --> 0:11:37.460000 Well, certainly I could take the same approach I just did. 0:11:37.460000 --> 0:11:40.500000 I could put that interface zero slash four into a different broadcast 0:11:40.500000 --> 0:11:43.820000 domain. I could put into VLAN three maybe. 0:11:43.820000 --> 0:11:48.380000 And then on that switch, I could say interface VLAN three and put my IP 0:11:48.380000 --> 0:11:50.600000 address of three, three, three, two right there. 0:11:50.600000 --> 0:11:52.560000 Or alternatively, I could do this. 0:11:52.560000 --> 0:11:54.400000 I could go on to this interface right here. 0:11:54.400000 --> 0:11:58.920000 So let's say it's a fast ethernet interface interface, fast ethernet zero 0:11:58.920000 --> 0:12:04.180000 slash four. And I could say no switch port. 0:12:04.180000 --> 0:12:09.600000 When you type the command, no switch port, you're telling the interface, 0:12:09.600000 --> 0:12:15.140000 hey, you are no longer one of a group of interfaces in a VLAN. 0:12:15.140000 --> 0:12:19.080000 It's no longer your job to switch stuff back and forth like other switching 0:12:19.080000 --> 0:12:23.320000 ports. You are now a routed port. 0:12:23.320000 --> 0:12:26.100000 You are now a port like a router has. 0:12:26.100000 --> 0:12:27.160000 Think about port. 0:12:27.160000 --> 0:12:28.860000 Now we don't call them ports on routers. 0:12:28.860000 --> 0:12:30.300000 We call them interfaces. 0:12:30.300000 --> 0:12:32.640000 But think about interfaces on routers, right? 0:12:32.640000 --> 0:12:35.540000 One interface on a router expects an IP address. 0:12:35.540000 --> 0:12:40.640000 He is a host in a particular network and he can route packets in and out 0:12:40.640000 --> 0:12:42.040000 of that network. 0:12:42.040000 --> 0:12:43.020000 Same thing here. 0:12:43.020000 --> 0:12:48.520000 Now that I've done no switch port, I can actually put my IP address right 0:12:48.520000 --> 0:12:53.160000 on that interface, right on the physical interface itself. 0:12:53.160000 --> 0:12:58.520000 And I can do a no shut. 0:12:58.520000 --> 0:13:02.440000 So that's the other way. 0:13:02.440000 --> 0:13:04.700000 You can put an IP address on your switch. 0:13:04.700000 --> 0:13:08.340000 Whether it be a switch virtual interface or whether you put on a routed 0:13:08.340000 --> 0:13:16.060000 port like I've just done right here, either method will work. 0:13:16.060000 --> 0:13:27.260000 All right. So we've talked about switch virtual interfaces. 0:13:27.260000 --> 0:13:34.260000 There we have one. 0:13:34.260000 --> 0:13:38.300000 If you do not plan on doing any kind of routing on your switch, if your 0:13:38.300000 --> 0:13:42.620000 switch is going to be a pure layer to switch and the only reason you're 0:13:42.620000 --> 0:13:45.740000 putting an IP address on there is so that you can ping it. 0:13:45.740000 --> 0:13:47.980000 You can tell that to it, but you're not going to route it. 0:13:47.980000 --> 0:13:50.440000 It's not going to know how to route. 0:13:50.440000 --> 0:13:52.160000 Then just like your laptop, right? 0:13:52.160000 --> 0:13:54.340000 Your laptop doesn't know how to route. 0:13:54.340000 --> 0:13:56.360000 It needs a default gateway. 0:13:56.360000 --> 0:14:00.180000 In this case, a switch also would need a default gateway if you're not 0:14:00.180000 --> 0:14:06.140000 going to configure routing or if he's not capable of routing. 0:14:06.140000 --> 0:14:11.160000 And of course, we can use ping or trace route or various show commands 0:14:11.160000 --> 0:14:15.700000 to configure or to verify our existing configuration. 0:14:15.700000 --> 0:14:20.100000 So let's just look at some quick configuration examples right here. 0:14:20.100000 --> 0:14:23.300000 So right now we're looking at the switch and we're paying attention to 0:14:23.300000 --> 0:14:24.660000 this interface right here. 0:14:24.660000 --> 0:14:28.880000 How do we configure that interface if he's connecting to a host? 0:14:28.880000 --> 0:14:31.260000 Well, you probably want to give him a host name. 0:14:31.260000 --> 0:14:33.080000 Then we go on to that interface. 0:14:33.080000 --> 0:14:36.200000 That's gig one, zero is five right there. 0:14:36.200000 --> 0:14:37.920000 You can give him a description. 0:14:37.920000 --> 0:14:38.580000 That's optional. 0:14:38.580000 --> 0:14:42.280000 You don't have to do that, but you can do that to make it more meaningful 0:14:42.280000 --> 0:14:45.120000 when you're looking at the config as to what does that interface connect 0:14:45.120000 --> 0:14:46.520000 to? Well, there's the description. 0:14:46.520000 --> 0:14:49.980000 It tells you. And the main command here I want to point out is switch 0:14:49.980000 --> 0:14:52.480000 port mode access. 0:14:52.480000 --> 0:14:56.420000 So when you say switch port mode access, that means this interface right 0:14:56.420000 --> 0:15:00.180000 here is only going to be in one VLAN. 0:15:00.180000 --> 0:15:04.420000 Now, notice in this configuration right here, there's no mention of what 0:15:04.420000 --> 0:15:10.020000 that VLAN is. So if we don't see it, if you do a show run and you see 0:15:10.020000 --> 0:15:13.280000 switch port mode access, but on this particular interface, there's no 0:15:13.280000 --> 0:15:14.600000 mention of what the VLAN is. 0:15:14.600000 --> 0:15:18.320000 It will be in the default VLAN in VLAN one. 0:15:18.320000 --> 0:15:23.960000 And then of course, no shutdown, which might be the default anyway, but 0:15:23.960000 --> 0:15:26.440000 no harm in doing that. 0:15:26.440000 --> 0:15:29.560000 So that's our interface leading to our host. 0:15:29.560000 --> 0:15:33.720000 Now, if we go a little bit further, now we say, okay, now I want to look 0:15:33.720000 --> 0:15:37.580000 at his interface leading into the core of the network, his interface leading 0:15:37.580000 --> 0:15:39.600000 to another switch. 0:15:39.600000 --> 0:15:45.360000 So now we're looking at interface gig one, zero, one. 0:15:45.360000 --> 0:15:50.560000 So same thing, you might want to put a description on it. 0:15:50.560000 --> 0:15:55.300000 And this command right here, switch port mode dynamic desirable. 0:15:55.300000 --> 0:15:56.640000 What does this do? 0:15:56.640000 --> 0:16:03.540000 This activates a Cisco proprietary protocol called DTP, which we'll talk 0:16:03.540000 --> 0:16:04.880000 about in just a few minutes. 0:16:04.880000 --> 0:16:08.340000 But essentially what this is doing is just saying, hey, I'm allowed to 0:16:08.340000 --> 0:16:11.760000 form a VLAN trunk if the other side is okay with it. 0:16:11.760000 --> 0:16:16.640000 If the other side of this link also does DTP and can exchange some DTP 0:16:16.640000 --> 0:16:20.820000 messages with me, then we can go ahead and form a trunk. 0:16:20.820000 --> 0:16:25.520000 If there is no DTP exchange, I would just stay as an access port. 0:16:25.520000 --> 0:16:28.740000 In this case, in the default VLAN, because we don't see any mention of 0:16:28.740000 --> 0:16:35.900000 VLAN. So if both of these links here are configured as switch port mode 0:16:35.900000 --> 0:16:40.440000 dynamic desirable, they will form a VLAN trunk. 0:16:40.440000 --> 0:16:45.620000 And then no shutdown, no shutdown once again as a, just a safeguard. 0:16:45.620000 --> 0:16:51.940000 And then here we see the other side of the link here we see switch two, 0:16:51.940000 --> 0:16:57.740000 which is just a mirror image of what we saw in switch one. 0:16:57.740000 --> 0:17:03.340000 Okay, a lot of times you will want to apply the same set of configuration 0:17:03.340000 --> 0:17:06.320000 commands across a range of interfaces. 0:17:06.320000 --> 0:17:10.080000 Like let's say you want to get on 10 interfaces and you want to do switch 0:17:10.080000 --> 0:17:13.000000 port mode dynamic desirable on all of them. 0:17:13.000000 --> 0:17:20.800000 Okay. So within switches, you can use the interface range command to do 0:17:20.800000 --> 0:17:23.200000 that. So here's how we can see it. 0:17:23.200000 --> 0:17:27.620000 So we're at global configuration mode, we say interface range. 0:17:27.620000 --> 0:17:29.780000 And here's how you specify your range. 0:17:29.780000 --> 0:17:34.820000 If you're going to do a range of continuous or contiguous interfaces like 0:17:34.820000 --> 0:17:39.520000 fast ethernet zero slash one through seven, then you just use a hyphen. 0:17:39.520000 --> 0:17:44.520000 Right. So the hyphen means they are all fast ethernet and interface zero 0:17:44.520000 --> 0:17:47.400000 one all the way up to zero slash seven. 0:17:47.400000 --> 0:17:52.680000 If you want to include in your interface range and interface that's not 0:17:52.680000 --> 0:17:56.400000 contiguous, then you use the comma. 0:17:56.400000 --> 0:18:01.120000 And after the comma, you have to again specify the type of interface. 0:18:01.120000 --> 0:18:04.680000 So for example, if I said interface range fast ethernet zero slash one 0:18:04.680000 --> 0:18:10.780000 hyphen seven comma zero slash twelve, it would give me an error message. 0:18:10.780000 --> 0:18:15.280000 Because maybe the switch has a gig interface of zero slash twelve as well 0:18:15.280000 --> 0:18:18.180000 as a fast ethernet interface of zero slash twelve. 0:18:18.180000 --> 0:18:21.100000 It wouldn't know which one to include in the range. 0:18:21.100000 --> 0:18:25.480000 So when you have a comma, you have to specify the type of interface as 0:18:25.480000 --> 0:18:28.280000 well as the number after that. 0:18:28.280000 --> 0:18:34.480000 And so now at this point, it puts me into the interface range mode. 0:18:34.480000 --> 0:18:38.940000 And now anything I type in at this point will apply across all this range 0:18:38.940000 --> 0:18:42.640000 of interfaces. Like in this case, I'm bringing them all up. 0:18:42.640000 --> 0:18:43.980000 I did no shutdown. 0:18:43.980000 --> 0:18:48.260000 I'm converting them all to access ports. 0:18:48.260000 --> 0:18:51.340000 Some routers will also support that. 0:18:51.340000 --> 0:18:55.080000 So if you want to configure range of fast ethernet or gig of it, ethernet 0:18:55.080000 --> 0:19:03.980000 interfaces on a router, go ahead and try it. 0:19:03.980000 --> 0:19:08.540000 For example, maybe not a lot at layer two, but for talking about routing. 0:19:08.540000 --> 0:19:12.500000 Right. Maybe at layer three, I want to go on to four interfaces on my 0:19:12.500000 --> 0:19:15.500000 router and put them all into OSPF area zero. 0:19:15.500000 --> 0:19:20.300000 I want to apply EIGRP authentication across all those interfaces at once. 0:19:20.300000 --> 0:19:23.760000 That would be a good use of using the interface range command on a series 0:19:23.760000 --> 0:19:29.300000 of router interfaces. 0:19:29.300000 --> 0:19:33.900000 Viewing the MAC address table, primary command is show MAC address dash 0:19:33.900000 --> 0:19:38.840000 table. And these ones here are ones that you should definitely be familiar 0:19:38.840000 --> 0:19:44.540000 with. The output of those commands and what you will see from those commands. 0:19:44.540000 --> 0:19:51.260000 Probably unlikely that you will ever add a static entry to the MAC address 0:19:51.260000 --> 0:19:53.800000 table, but it is possible to do that. 0:19:53.800000 --> 0:19:57.980000 So in that case, it's just MAC address dash table static. 0:19:57.980000 --> 0:20:03.160000 Once you type that in, you follow it with the MAC address you want. 0:20:03.160000 --> 0:20:05.060000 The interface name and number. 0:20:05.060000 --> 0:20:08.820000 So you'd actually say like interface gigabit zero slash one, and then 0:20:08.820000 --> 0:20:11.720000 the VLAN, the VLAN number. 0:20:11.720000 --> 0:20:17.060000 And for basic troubleshooting, things aren't working right. 0:20:17.060000 --> 0:20:17.920000 Check the cable type. 0:20:17.920000 --> 0:20:19.480000 Remember, right? 0:20:19.480000 --> 0:20:21.200000 Similar to similar, right? 0:20:21.200000 --> 0:20:24.860000 Switch to switch requires crossover cable. 0:20:24.860000 --> 0:20:29.420000 This similar device is like switch to router requires a straight through 0:20:29.420000 --> 0:20:33.420000 cable. So make sure you got the correct cable type. 0:20:33.420000 --> 0:20:36.400000 Ensure the interface is not administratively down. 0:20:36.400000 --> 0:20:42.160000 Make sure the no shutdown command was typed in. 0:20:42.160000 --> 0:20:45.720000 For access ports check for the same VLAN. 0:20:45.720000 --> 0:20:51.680000 So if I have two hosts, they're saying, hey, we're both in the 10 network. 0:20:51.680000 --> 0:20:52.980000 I'm 10, 1, 1, 1. 0:20:52.980000 --> 0:20:54.520000 I'm 10, 1, 1, 2. 0:20:54.520000 --> 0:20:56.820000 We should be able to talk to each other, but we can't. 0:20:56.820000 --> 0:20:58.900000 Well, make sure those two hosts are in the same VLAN. 0:20:58.900000 --> 0:21:03.260000 Otherwise, they won't be able to communicate. 0:21:03.260000 --> 0:21:06.200000 And verify DTP compatibility modes. 0:21:06.200000 --> 0:21:09.220000 We'll talk a little bit more about that in just one moment. 0:21:09.220000 --> 0:21:16.100000 All right. So that is it for basic switching and basic switching configuration 0:21:16.100000 --> 0:21:19.820000 review. Thank you so much for watching this recording.