Troubleshoot Network Devices

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57 minutes
Video Transcription
Welcome back. In this episode, we're gonna take a look at how we can troubleshoot network devices.
The objectives include we're gonna talk a little bit about physical connections, an overview of basic configuration on network devices and understanding your network architecture.
So, first, let's talk about physical connections. So far, we've primarily just been using tools inside the operating system to verify connectivity or it even captured network packets.
One of the things you need to check first, though, is actually verifying the status of your network cable. Whether it's plugged in, maybe it has some damage or is just not a good cable anymore.
I know that seems pretty basic, but it can save you a lot of headache and troubleshooting if you just verify some of those things first.
Secondly, also, verify your network card. If it's ah, network adapter that's not built into the mother board, you may want to verify that it's still seated in its slot. Or it can even have damage to the inside of the network card. I've definitely seen that before, where someone may have taken something to it like a screwdriver, something to get a stuck network cable out.
So again, just like verifying the quality of your network cable. Also, verify the quality of the network card and make sure doesn't have any damage.
And speaking of the network card, also verify if there's any network activity. Lights on the network card. Here's a quick photo I took of the back of my home server that I have and you can see We've got a couple of different lights there and those will flash and show if they have connectivity or if there's network traffic currently occurring on them.
So definitely check that out. Make sure that's working again. That goes along with verifying the quality of the network heart of making sure there's no damage with it.
Next, you want to make sure the network device that you're actually connected to is available again. Sounds pretty basic, but it can save you a lot of headache if you double check these things,
For example, make sure it does have power and is currently powered on and has network connectivity itself. This is where that ping utility is gonna come in handy. You will want to paying the gateway or the I P address of the network device and actually see if it's on the network
and then perform things like a tracer out to see if he can actually get to it. Next. You'll want to see if you can access the admin interface, either. If it has a gooey or admin webpage, you can access their Web browser. Or you can even connect to network devices over Ssh and see if you can lock in and access it.
Finally, if you're able to see if you can actually plug into the device yourself. And if you have network connectivity to
now, once you get access to the network device, you wanna double check its configuration.
We take a look at a couple of things from a screenshot here. This is from my own switch that I have in my home network. It's a very basic kind of small, medium business type switch, but it does have a couple of capabilities and configurations. You can double check first. You'll want to verify the poor connectivity so say, you know you're plugged into a specific port.
Go see if the port actually sees that it has a device
attached to it.
Here, you can see link down for port one and three, but it does show we have something active on port to.
So if I actually had something plugged into Port three, but it should link down, that would show me something's going on with that port next verified, the port is actually enabled. Here you can see Port One actually is disabled as its status, and there's some organizations that do this.
They will disable ports that aren't being actively used. And if you happen to plug into a network jack, you'll have to map that into a network closet
and actually go turn on or enable the port on the switch. This prevents anybody from just plugging in a device randomly into a network port in having access.
Next, you'll want to check the port speed configuration of the port on the network device,
for example. Here I have auto configuration for Port one and two, meaning it's just going to auto configure the speed for the device that's connected to it.
But im Port three. I have 10 MH, which stands for a 10 megabit half duplex,
so duplex refers to sending and receiving data at the same time. But if I have it set to half duplex. That means it can only send or receive data, not both at the same time.
So if you're running into slow network speeds, just double check the port speed configuration to make sure something hasn't been configured on it to limit the speed or band with.
Finally, you'll want to verify the V Land that the port is actually in now. V land. Something we haven't discussed is just basically sitting up virtual land or networks on a single device. In order to segregate traffic,
you could be plugged into a port and expecting to have access to something. But that port may not actually be part of the V Lane you think it is.
Finally, let's talk about network architecture.
In order to effectively troubleshoot the network into your environment, you need to know how it set up, and this could be done through documentation and diagrams. It's very important toe. Have the network architecture documented so you can reference it to understand the network flow inside your environment.
This is important so you can understand the traffic flows and how things
come in and out of your network from the Internet or to other branch or main headquarter sites.
You also need to know where your security devices are, such as firewalls or proxies. While all your network devices and Internet connections may be up and running, there could be other devices, like the proxies or firewalls that are blocking or impeding traffic.
So you'll need to know where those are in order to test traffic on each side of them and verify if that's the cause of the issue
that does it for this lesson. Just a short overview of some things to think about when you're troubleshooting network devices and a few things you can check, can't get super specific just because every vendor is gonna have their set up just a little bit different. Lovely. That gives you some things to think about why you're troubleshooting network issues. In this lesson, we talked about verifying your physical connections
both on the system and on your network device
verifying device configuration. Mega, she reports, are enabled and aren't limited with their speed negotiation
and finally understanding your network architectures. So you know how your network traffic flows and other devices that may cause issue in that path,
and this is actually the last lesson in our course. Let's have a quick summary of what we've talked about.
First, we looked at verifying our network configuration. Using tools like I p config.
We looked at trouble shooting network connectivity. Using ping and trace route,
we verified domain name resolution. Using s look up,
we looked how we can modify our route tables Using the route command,
we can test ports and protocols with tools like Net Stat and Telnet.
We took a look at third party networking tools that we can use to capture and analyze network packets
and finally, a brief overview of how we can troubleshoot network devices
again. This is just a quick overview of everything we have available to us. It's up to you to practice these things, so you are able to utilize them effectively when the time comes and you're troubleshooting a big issue.
Thank you for watching, and we'll see you next time