Category Archives: VLANs

What is Link Layer Discovery Protocol (LLDP)?

Understanding LLDP and LLDP-MED The smooth running operation of the various networking devices in a LAN or switched network means that all protocols and applications are enabled and that all devices and are configured correctly. However, the larger the network gets, the more difficult it will be for the network administrator to control, manage and sort out configuration problems. This… Read More »

What are Common Network Security Threats?

Three common factors emerges when dealing with network security, these are vulnerability, threat, and attack. Vulnerabilities An experienced hacker knows that every network or device has a certain degree of vulnerability or weakness, and they take advantages of each security weakness or loophole to exploit the network.  A  Computer network hackers work round the clock in search of unsecured… Read More »

Configuring VLAN Trunk Example

How to Configure a Trunk Port. To configure a trunk on a switch FastEthernet port, use the switchport mode trunk command. This command puts the interface into permanent trunking mode and negotiates to convert the neighboring switch or links into trunk links. Lets use the topology below. The VLANs 10, 20, and 30 will support the management, IT, and Sales… Read More »

What is Router on a Stick Inter-VLAN Routing? How to Configure

When configuring InterVLAN routing, it’s advisable you firstly, configure the switch SW1 that will be connected to the router, as shown in the diagram.  Router R1 is connected to switch ports F0/4 and F0/3, which have been configured for VLANs 10 and 20, respectively. Example of switch SW1 interface configuration command: SW1#config t SW1(config)#vlan 10 SW1(config-vlan)#vlan 20 SW1(config-vlan)#exit… Read More »

How to Configure InterVLAN Routing Example

Configuring InterVLAN routing on Cisco Router. When configuring InterVLAN routing, it’s advisable you firstly, configure the switch SW1 that will be connected to the router, as shown in the diagram.  Router R1 is connected to switch ports F0/4 and F0/3, which have been configured for VLANs 10 and 20, respectively. Example of switch SW1 interface configuration command: SW1#config… Read More »

What is InterVLAN Routing ? Explained with Examples

We define inter-VLAN routing as a process of forwarding network traffic from one VLAN to another VLAN using a router or layer 3 device. In the previous pages, we learned about how to configure VLANs on a network switch. To allow devices connected to the various VLANs to communicate with each other, you need to connect a router. As… Read More »

Troubleshooting VTP: Incorrect VLAN Configuration and Solution

We’ve learned that VLAN is a means of transmitting packets across a switched network via a trunk link, also for traffic from a VLAN to be transmitted across a trunk it has to be allowed access on the trunk. The command used to do this is the switchport access trunk allowed vlan add {vlan-id }command. In the topology diagram below, VLAN… Read More »

Managing VLANs in a VTP enabled Network Explained

How To Manage VLANs in a VTP Enabled Network. In the last few pages, we have learned how to manage VLANs in a VTP-enabled network. When a new VLAN, for example, VLAN 30, is added to the network, the network administrator adds the VLAN to the VTP server, switch SW1 in the diagram. For the record, the primary… Read More »

What is Router-on-a-stick Inter-VLAN Routing ? Explained with Examples

What is Router-on-a-stick Inter-VLAN Routing? Router-on-a-stick is a type of router configuration in which a single physical interface manages traffic between multiple VLANs on a network. The router interface have to be configured to operate as a trunk link and is connected to a switch port (SW1) which will have to be configured in trunk mode. The router receives VLAN tagged traffic… Read More »

What is interVLAN Routing ? Troubleshoot InterVLAN Routing?

How To Troubleshoot: InterVLAN Routing. As I have mentioned earlier on other troubleshooting page(s), one of the commonest mistake administrators make during networking is made during configuration stage, either on the router, switch or logical subnet addressing. On this page(s), we’ll look at the challenges; common issues and troubleshooting methods related with configuring multiple VLANs on a network. If you… Read More »