Configure a Network using VLANs

Hi all,

I’m again with awesome networking activity. Here’s my requirement, I need to configure a network to connect Airport and an archeology department of my country. But the thing is I need to consider some important points regarding security and cost. For achieving these two points I’m going to introduce special Local Area Networking technology call Virtual Local Area Network, I think most of networking students familiar with the short term use for identifying this technology, that is VLANs.

In my requirement I clearly mention about mainly two things, those are Security and Cost. Basically, most of networking scenarios we use VLANs for achieve these two goals. Now see how to achieving these two goals using VLANs.

Most of networking devices which are used to configure network are very costly. When we going to configure network in organization we need to achieve their basic requirement such as communication issues, but we should consider the cost also, otherwise organization wants to fired few employees for cover networking budget. Another thing is security, let’s focus again to the same scenario. Most of organization separate as the different section as the finance, management, HR like wise. Lot of operations done in these section done by independently. Because of these kind of situations we can’t configure whole organization using same LAN. So in order to mitigate security issues in our networking team going to introduce 3 separate LANs for HR, Finance and the Management. Three separate LANs mean we need to use three switches that point, lead for our project into very large budget, now we need to think how to avoid high budget. Virtual Local Area Network (VLAN) comes up with a solution for that, As the name says we’re going to configure three different networks in a virtual manner rather than using three switches.

Ok let’s see how to do it.

Here’s the network diagram I designed using CISCO Packet tracer.

1. Set default gateways in sub interfaces in ‘AirportRouter’

AirportRouter(config)# interface FastEthernet0/0

AirportRouter(config)# no shutdown

AirportRouter(config)# interface FastEthernet0/0.10

AirportRouter(config)# encapsulation dot1Q 10

AirportRouter(config)# ip address 172.10.10.254 255.255.255.0

AirportRouter(config)# interface FastEthernet0/0.20

AirportRouter(config)# encapsulation dot1Q 20

AirportRouter(config)# ip address 172.20.20.254 255.255.255.0

AirportRouter(config)# interface FastEthernet0/0.30

AirportRouter(config)# encapsulation dot1Q 30

AirportRouter(config)# ip address 172.30.30.254 255.255.255.0

2. Set VLANs in ‘AirportSwitch’

AirportSwitch(config)#VLAN 10
AirportSwitch(config)#Name HR

AirportSwitch(config)#VLAN 20
AirportSwitch(config)#Name Finance

AirportSwitch(config)#VLAN 30
AirportSwitch(config)#Name Management 

3.Set ports as a trunk port.

AirportSwitch(config)#Interface fastethernet 0/1
AirportSwitch(config)#switchport mode trunk 

4.Assign VLANs to the ports.

AirportSwitch(config)#interface FastEthernet0/1
AirportSwitch(config)#switchport mode trunk

AirportSwitch(config)#interface FastEthernet0/2
AirportSwitch(config)#switchport access vlan 20
AirportSwitch(config)#switchport mode access

AirportSwitch(config)#interface FastEthernet0/3
AirportSwitch(config)#switchport access vlan 20
AirportSwitch(config)#switchport mode access

AirportSwitch(config)#interface FastEthernet0/4
AirportSwitch(config)#switchport access vlan 30
AirportSwitch(config)#switchport mode access

AirportSwitch(config)#interface FastEthernet0/5
AirportSwitch(config)#switchport access vlan 10
AirportSwitch(config)#switchport mode access

AirportSwitch(config)#interface FastEthernet0/6
AirportSwitch(config)#switchport access vlan 10
AirportSwitch(config)#switchport mode access

AirportSwitch(config)#interface FastEthernet0/7
AirportSwitch(config)#switchport access vlan 10
AirportSwitch(config)#switchport mode access

AirportSwitch(config)#interface FastEthernet0/8
AirportSwitch(config)#switchport access vlan 20
AirportSwitch(config)#switchport mode access

AirportSwitch(config)#interface FastEthernet0/9
AirportSwitch(config)#switchport access vlan 10
AirportSwitch(config)#switchport mode access

AirportSwitch(config)#interface FastEthernet0/10
AirportSwitch(config)#switchport access vlan 10
AirportSwitch(config)#switchport mode access

AirportSwitch(config)#interface FastEthernet0/11
AirportSwitch(config)#switchport access vlan 10
AirportSwitch(config)#switchport mode access

AirportSwitch(config)#interface FastEthernet0/12
AirportSwitch(config)#switchport access vlan 10
AirportSwitch(config)#switchport mode access 

5. Configure Routing protocol in ‘AirportSwitch’.

AirportRouter(config)#router eigrp 110
AirportRouter(config)#network 10.0.0.0
AirportRouter(config)#network 172.10.0.0
AirportRouter(config)#network 172.20.0.0
AirportRouter(config)#network 172.30.0.0 

If you need more clarifications, you can refer this packet tracer file. [CISCO Packet tracer File]

Best Regards,

Denuwan Himanga   

Dynamic IP configuration

Hi, everyone,

After long time, it’s time for sharing some knowledge with you. Today I’ll go through the one of the hates interesting fields most students who study in information technology area. I know the Networking is a little bit complex study area, but believe me when you catch the correct way to configure something in this field, it would be the most interesting thing ever you feel in your student life. 

Today we’ll go through the small interesting area, call Dynamic IP configuration, another word DHCP configuration.  

  

In larger networks, we know it’ hard to configure each PC one by one manually or else in the technical word static IP configuration is hard in the very large and complex networks. For avoiding these kind of issues we can use DHCP configurations. 

For illustrating purpose I’ll use Cisco Packet trace simulator, I didn’t wish to introduce this amazing simulator at this time, but without deep knowledge you can play within this simulator it’s 100% user-friendly! You can simply drag and drop devices and use it. I think most of student who study in networking field familiar with Cisco Packet trace.

Before DHCP configuration you should complete three preconditions.

1.      Establish a physical connection using correct tools/wires/devices.

             

Here’s the network I designed using the simulator

2.      Configure router interface which is connected with LAN segment.

I’ll use 172.100.100.1/24 IP form 172.100.100.0/24 IP slot for configure this interface.        

Here’s the code which is use for configure router’s interface

3.      Exclude the set of IP address for servers. 

Usually we didn’t configure dynamic IPs for servers, it would lead to security issues for avoiding these kind of security issues we must configure servers using the static IP configuration method, At this time we didn’t go to configure servers. So for the future purpose, we will reserve same IP address from our IP address slot. In this scenario we reserved 9 IP address from our IP address slot (172.100.100.0/24).

Here’s the reserved IPs

172.100.100.2

172.100.100.3

172.100.100.4

172.100.100.5

172.100.100.6

172.100.100.7

172.100.100.8

172.100.100.9

172.100.100.10

Here’s the code using for exclude above IP address from IP slot 172.100.100.0/24

Router(config)#Ip DHCP excluded-address 172.100.100.2 172.100.100.10

Then you can follow the following steps for DHCP configuration. 

DHCP configuration can do by following 3 easy steps, follow the steps with me, and believe me it’s not much harder you think.

1.      Name the DHCP pool name

We can use any word without space. That word is the name of our DHCP pool. I’ll use ‘IP_DHCP_POOL’ word for named my DHCP pool.

Router(config)#Ip DHCP pool IP_DHCP_POOL

2.      Set the network and it’s subnet mask

I’ll use the 172.100.100.0/24 network IP slot

Router(config)#Network 172.100.100.0 255.255.255.0

3.      Set the default router path

As you can remember, the preconditions I completed in first three steps I configured the router’s LAN segment side interface using 172.100.100.1/24 IP. This is the default router, gateway I should for this step.

Router(config)#Default-router 172.100.100.1

Here we go, we done!

Now you can go to PC’s IP configuration mode and the put the tick mark to the DHCP, It will automatically configure your PC regarding configuration which is configured in above mentioned steps. 

** It will use IP’s from the IP slot skiing the excluded IPs. Also, it follows the first come, first serve (FCFS) method for the PC configuration stage. When you click fist PC it will configure 1st IP available from IP slot, then second PC for a second IP likewise. It doesn’t consider the interface port label or anything.   

Regards,

Denuwan Himanga.