Category Archives: network

Cisco IOS Fundamentals

cisco

Cisco’s IOS is a command line driven interface for all their devices. There are some basics for logging into a device. Such as physically connecting to the device console port with a serial port, or a roller over cable. For no i’m going to discuss the basic hierarchy to get into configuring the device. One of the most important commands to learn is the “?” command. At any time if you need to know the command that are available to you you can just type in “?”.

? output for user mode

The next thing you should know is the hierarchy into which you need to progress the get though to be able to configure the device i’ll try to make a simple table below.

Mode chart

To configure a device you must move through the hierarchy into the global mode. user>privilege>global. In the next image I’ll walk though these mode until a reach the interface mode.


user>privilege>global>interface

Thank you for reading. I’ll definitely continue these article later.

Network Troubleshooting Part 1

Command Line

Even as enterprise infrastructure is moving towards the cloud, physical terminals, clients, devices ect… need to connect to that cloud. Even with wireless networking those wireless access point still need a wired connection. So this is how i go about checking for network connectivity.

Step 1: Check the Physical Layer. If a machine is not connecting to the network. I always pull it out and look at the link state lights. If i see green or amber flashing or steady. I then know at least the machine is connecting to something on the other end. If i don’t see any lights or red lights then i know the problem is somewhere in the physical layer.

Ethernet Link Lights

Often when i pull out the client box i’ll look for any bad kinks in the Ethernet. It not a common occurrence but is its possible that a really bad kink has cause internal rubbing and cross talk noise or even complete failure of the twisted pairs inside the Ethernet.

Step 2: Check the network device settings. You can read more about network device settings here. There is various ways of doing this if you’re on a windows based device with command line “ipconfig /all” you bring up all the relevant adapters and their current configurations. If you’re on a linux based system “lfconfig” will do the same.

ipconfig output

It is important to check the site’s documentation to see if the gateway is correct or if there is a possible ip address conflict. Also it very important to see if the machine is on the right VLAN. I’ll talk more about VLANs and sub netting in another blog article.

Thank your for reading please keep an eye out for part 2.

Networking Setup

CCTV

Out of the box most device are set-up with DHCP protocols and this will make it pretty easy for the end user just to plug the device in and get it connected. But if you are in a larger more complex network you might need to set up a static ip for the device. In most windows devices you can use the wizard walk you through it but if you need to setup like 20 ip cameras you should at least know the basics. I’ll use windows for this as it is the easiest to capture. If you go to Control Panel>Network and Internet> Change Adapter Settings>(connection which you want to set up)>Internet Protocol Version 4 (TCP/IPv4)>properties. You will finally reach a window like this:

I you are in a network that has DHCP enable all you have to do is have “obtain and ip address automatically” check and the number fields will be grey out. But if you to setup up a static IP for you machines you will need to have these filed filled out. Usually the network administrator will give you the information you need to fill in the slots.

But a quick rundown is the IP address that is assigned is basically the address for the device. Anyone looking for the camera will use this ip address to connect with it.

The subnet mask is used to create vLANs. A vLAN is basically a subdivided part of the network that only other devices with the same subnet mask can see and interact with. It is used for security and organization purposes.

The Gateway is is the device on the network usually a router that will allow the device you are setting up to access other networks like the internet.

I’ll go into more about the DNS and subnetting later, but in summation once you know what these numbers are you can easily setup any device on a network easily not just a windows machine.

Networking Basics

network

One of the most important skills in IT is networking. Even if you aren’t specializing in networking it is important to know a few things. So this is sort of a primer or cheat sheet for networking. The most used model for networking is the TCP/IP model. The basics can easily be summed in in a simple mnemonic Please Do Not Throw Sausage Pizza Away, or

mnemonicTCP/IP layerProtocols
AwayApplicationPOP, SMTP
PizzaPresentationJPEG,GIF
SausageSessionAppleTalk, SCP
ThrowTransportBGP,DHCP,DNS
NotNetworkDDP, EGP,EIGRP
DoData LinkEthernet,PPP
PleasePhysicalCables

Basically the data that is sent between 2 machines is encapsulated according to this model most layer encapsulating the one before it. If you can find fault in the physical layer or the application layer you might need to capture a packet and look at where the fault is in the network. Packet capture essentially lets you view a packet transmitted across the network. You can then view that packet and see thing like who it was meant for on the network and what data it contains.

Cisco’s IOS Overview

cisco

Cisico’s IOS operating system is very different from Apple’s iOS, and the two should not be confused. Ciciso’s IOS is an operating system design to work on very specific hardware, mainly routers and switches that Cisco sells. Is is a command line only system that runs with very low over head that means cisco’s equipment can be very efficient not worrying about user interfaces and graphical processing. That means the size of the OS is still remarkable small most versions of IOS are around 8 MB to Download and 32 MB to run. One of the requirements to download are registering with Cisco and having a service contract to actually run IOS on your equipment. It is generally not available to the public. While non tier 3 switches don’t need IOS, as their hardware is ASIC based. Tier 3 switches inherit functionality from routers and need knowledge of IOS to configure. One of the most interesting qualities of Cisco IOS and routers is the fact that they’re designed to require little or no user interaction in their service life. This “Bullet-Proof” quality of their products is important to most companies as networks are often the backbone that keeps the company working. All vital networks should have redundancies to deal with any issue that might come up. So who should use Cisco routing and switching gear? really most businesses that rely on their computer for daily business but we’re seeing more and more businesses that require solid networks in their locations like fast food restaurant integrating self serve POS terminal for their customers.