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September 2015

INTRODUCING… JESUS AND MO | Pandaemonium

Source: INTRODUCING… JESUS AND MO | Pandaemonium

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Ad Blocking and the Future of the Web — Medium

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My Journey Into Cisco Routing and Switching

As a professional in the IT sector, I’ve always heard the hype about Cisco products and how difficult they were to configure. While looking at job postings, many of them had the CCNA certification as a requirement for consideration. I’ve always wondered why this was the case as most small and medium scale enterprise use a variety of network devices from different vendors. Surely, Cisco cannot have precedence over all of them. I believe one should have a solid understanding of network and system administration principles to be able to build, configure and administer a network environment using any network device available to you. As a result of this orientation, I was always sceptical about taking a Cisco certification.

My first encounter with a Cisco product came while I was employed in a high end nursery school. The proprietor of the nursery had purchased a Cisco 1800 series router and a Cisco adaptive security appliance device together with a couple of Netgear managed switches. I thought to myself, this should all be fairly easy to configure considering the network topology of the nursery.

We decided to create two VLANs to handle data and video services respectively. The managed Netgear switches were very easy to configure as they had a user-friendly Graphical User interface (GUI). All you have to do is to connect a pc to an Ethernet port on the switch and type in an administrative IP address on a web browser and you were in.

VLAN-Membership
Netgear Managed Switch GUI

The Cisco 1800 series router on the other hand was a different kettle of tea. First, you have to connect your pc to the router using a console port cable. Most PCs today do not have a console port, so you have to get a console to USB adapter and install the drivers on your PC before you can attempt a connection. Once the connection was established, I had to figure out how to configure the Cisco router using the command line interface (CLI) as there was no GUI.

cisco
Cisco CLI

I and a colleague of mine carried out some research using Google, the Cisco website and lots of technical blogs out there on the internet. We first had to figure out that some commands run only in privilege mode or in global configuration mode or in interface configuration mode. Then we learnt how to create user names and secret passwords and how to configure access to the router via Telnet and SSH. After that, we decided to use the router as as DHCP server as our windows server had licensing issues at the time. we then figured out how to configure VLANs on the router interfaces and finally, we concluded with the NAT configurations.

Some of the commands we used:

enable
configure terminal
hostname nursery
hostname TTKCRouter
!
enable secret 5 blablahashblah
enable password chima
!
ip dhcp excluded-address 192.168.90.1 192.168.90.50
ip dhcp excluded-address 192.168.50.1 192.168.50.50
!
ip dhcp pool video
network 192.168.90.0 255.255.255.0
default-router 192.168.90.1
dns-server 8.8.8.8
!
ip dhcp pool Data
network 192.168.50.0 255.255.255.0
default-router 192.168.50.1
dns-server 8.8.8.8
!
!
ip cef
multilink bundle-name authenticated
!
!
username chima privilege 15 password 0 blablabla
!
!
!
interface FastEthernet0/0
no ip address
duplex auto
speed auto
no mop enabled
!
interface FastEthernet0/0.50
encapsulation dot1Q 50
ip address 192.168.50.1 255.255.255.0
ip nat inside
ip virtual-reassembly
!
interface FastEthernet0/0.90
encapsulation dot1Q 90
ip address 192.168.90.1 255.255.255.0
ip nat inside
ip virtual-reassembly
!
interface FastEthernet0/1
ip address 1.2.3.4 255.255.255.252
ip nat outside
ip virtual-reassembly
duplex auto
speed auto
!
ip forward-protocol nd
!
!
no ip http server
ip nat source list 10 interface FastEthernet0/1 overload
ip nat inside source list 10 interface FastEthernet0/1 overload
ip route 0.0.0.0 0.0.0.0 192.168.2.1
ip route 0.0.0.0 0.0.0.0 1.2.3.5
!
access-list 10 permit 192.168.0.0 0.0.255.255
!
control-plane
!
!
line con 0
line aux 0
line vty 0 4
privilege level 15
password #blablabla
login local
transport input all
!
scheduler allocate 20000 1000
end

Passwords and IP address details have been changed

At the end of this scenario, we had a fully configured LAN with access to the internet. My experience with Linux CLI made it easier for me to use the Cisco CLI and I realised that it is much more easier to administer a Cisco device using the CLI.

These challenges convinced me of the necessity to educate myself on Cisco routing and switching technologies. Since then, I have started the CCNA routing and switching course and I have learnt a whole lot about networking in general and Cisco device configuration in particular.

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