From the course: CompTIA Network+ (N10-009) Cert Prep

Cisco commands

From the course: CompTIA Network+ (N10-009) Cert Prep

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Cisco commands

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- Welcome to the world of Cisco. Now, I do realize, and we all realize that CompTIA is a very vendor-neutral organization, but the exam has placed a couple of commands that you need to understand, know how to use, and they're very basic commands, so I don't want you to get too intimidated, and those commands can be performed on Cisco devices. So before we get started, let me show you my setup I have here. I have an old, we're going old school today. I have an old Cisco Catalyst 2950 Switch. I have my laptop, and here I have a console cable, or a rollover cable, or better known as a Yost cable. That's a very interesting word, Yost. It sounds like I bought this on Tatooine at the Mos Eisley Cantina. But anyway, we're going to connect this up. So there's a console port on the back of your Switch, and we just connect it here. Oh, a little nub is broken off this cable. That's not good. And normally, the other end is serial, but because serial is so outdated, they have these converters. So I have a serial to USB converter, and I'm going to plug this into my laptop. Okay, let's roll. I'm going to open up a program, called Putty, and this is a typical program that you would use when you're consoling into a Cisco device. Now, I already know, from checking my device manager, that I am using COM4, which is part of the serial port. So I have to change this to serial, and I'm going to set this to COM4, and the baud rate will be 9,600, leave that by default. And we click open. Oh, hold on a second, it may have... This is a good thing people, it's always a good thing when things don't always go the way we planned. Let's check device manager. Ah ha, it moved it to COM5. See? Good thing I did that. Okay, back to serial. Change this to COM5. Okay, let me go into, expand this for you, in the window. Sometimes this takes a little bit. Okay, we press enter. Now this looks pretty uninteresting, especially if you've seen other episodes where we're using a gooey interface, like on the Ubiquity Switch. So the first command I want to show you is the enable command. Now, there's something you you need to understand about Cisco iOS. By the way, this is called iOS, it's Cisco's CLI interface, is that you can actually type commands in shorthand, and it'll still work, but if you're, like, I teach my students, when I'm teaching 'em the CLI for A+ is that when in doubt, type it out. So we'll use the full command on some of these. So the first command is an enable. Notice here you'll see that it says, "Switch," and it has a greater than sign. That means you're in regular mode. We have to go into what's called privileged mode. So we type enable. Now if you're smart, you would've already configured a password on this, which I did, and I'm not telling you what it is. Okay? Okay. Now notice my prompt has changed from a greater than sign to a pound sign, or hashtag sign, whatever you call it. So this tells me that I am now in privileged mode. So now that we're in privileged mode, I'm going to show you your first privileged mode command, and this is to show the running configuration. You can type show config, but let's just type the whole thing out. Show running-config, and we'll press enter, and it's going to give us a bunch of information about our Switch. We're not using spanning tree at the moment. Here are all of our interfaces. Some are configured for Switch port mode access, which is basically an access port. And we hit the space bar, and there we go. Okay, oh, look at this. It actually shows my password. That's not good. Thank God no one's shoulder surfing over me. I would never fall for that. So the next command I want to show you is show interface. Now, if I do a standard show interface, it's going to show me every single interface, and it's going to be a very long process of every single one. I don't want to do that. So I'm going to show the interface for a specific port. Now these are fast ethernet ports. You would type FA space. Let's show the interface for port one. You would do 0/1. And it's going to give me some information about this. You know, time out, SaaS input, output. Some of these things I probably have to refer back to the manual, see what they are. But an interesting thing here, check this out. We got runts and giants. These are actually two terms that are on the exam, and runts are pretty much packets that are underneath the required amount of bytes, and giants are larger than they should be. So let's continue on. Okay. Now another command that you need to know is show route. (laughs) I got you. Did you actually think that was going to work? This is not a layer three Switch, but show route is a command you need to know that can be on a layer three Switch, or a router. Here's a snapshot of one. Okay, and there's one command that I want to just show you for fun in case you decide to tinker around with one of these things at home is that if you're going to make any sort of configuration changes, you have to make sure to save it. So what that's called is called copy the running configuration to the startup configuration. This is the one I'm going to give you an abbreviated command, copy run start. If you don't do this, it's not going to save your changes. So it's going to ask you a destination file name, you say enter, and you're good. And of course, the last command you could type is exit, or you can use control Z. And there you have it. Folks, I want you to understand something, there are two types of network people out there. There are Cisco network people, and then there's everybody else who likes to use Juniper or Ubiquity. But for this particular episode, I wanted to show you those commands that you will see on the exam, and tinker around. Go on Google, grab a Cisco book, tinker around. These things are pretty cool, and you really should know the iOS interface, especially considering that Cisco really has a big hold in the market. - Great job, Joe, but let me cover a couple of new topics. There are times when you need to learn the Mac address of one or more devices on a LAN. Switches create and maintain Mac address tables for devices associated with their ports. To display the Mac address table on a Switch, the command is show mac-address-table, and you want to put hyphens in between those. So go ahead and type out S-H-O-W, space, M-A-C, hyphen, address, hyphen, table so it looks like only two words. Understand that the Mac address entries in the Mac address table on a particular Switch are only those with which the Switch has a direct contact. If there are more than one Switch inside of your network, this action may need to be repeated for each Switch. There are also times when you need to find the IP address that corresponds to a particular Mac address, or the reverse. On virtually all Switches of a manufacturer, this information is kept in the address resolution protocol table. In fact, this information is kept even on Windows or Linux PCs, as well. On many Switches and operating systems, the ARP command will display the contents of the ARP table, otherwise known as the ARP cache. On a Cisco Switch, the command is show ip arp, or show arp. If you wish to display the ARP table on a particular device, if you want to know where that device actually is for your ARP table, add the IP address to it at the end of the command to give you just that distinct information. On a network in which VLANs have been configured, you can use the show VLAN command to display the VLANs, their statuses, and their port associations. To see if a particular port is associated with the VLAN, use the command show run interface with the port ID. Should you suspect that a Cisco Switch may have a power supply issue, you can check its status by using the show environment power command. This displays the status, capacity, and output power level of the devices power supply. And there's one command that I want to just show you just for fun in case you decide to tinker around with things at home, is that if you're going to make any sort of configuration changes on Cisco iOS, you have to make sure that you save it. Otherwise, when it reboots, you'll lose any commands that you've done.

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