The VLAN Trunking Protocol (VTP) is used to manage the configuration of switches that are part of a VTP management domain, as we learned in Chapter 3. Recall that three VTP modes exist – server, client, and transparent mode. Once a VTP server is configured, any changes made (such as adding or removing VLANs) will […]

Earlier in Chapter 3, we looked at ways to connect switches with trunk links, such that VLANs could span multiple switches. The two main ways to accomplish this are via the Inter-Switch Link (ISL) and 802.1q frame tagging methods. The Cisco 1900 series does not support 802.1q, leaving ISL as the only option for creating […]

A VLAN is essentially a broadcast domain, assigned according to switch ports. By default, all ports on a Cisco 1900 are assigned to VLAN 1, sometimes referred to as the management or administrative VLAN. In order to implement additional VLANs, you will first need to define them, and then add ports to that VLAN. New […]

In some cases, it may not make sense for all traffic to be trunked to all switches. For example, consider the network diagram shown in the figure below. In it, Switch C does not have any ports configured on VLAN99. As such, it doesn’t make much sense for traffic destined for VLAN99 to be sent […]

Switches can operate in three different VTP modes, which affect the way in which they share or interact with VTP advertisements. Once configured, VTP information is stored in their VTP database. The three modes include:
Server. By default, every Catalyst switch configured to use VTP will be configured as a server. In any VTP domain, at […]

In large networks, configuring VLAN information on each and every switch would be incredibly time consuming. In order to deal with this issue, Cisco created a protocol referred to as the VLAN Trunking Protocol (VTP). VTP actually has very little to do with trunking. Instead, its responsibility is propagating information about the configuration of VLANs […]

VLAN tagging is not a difficult concept – just remember that its purpose is to allow frames from multiple VLANs to be transferred across a trunk link and properly identified at the other end.
Recall that ISL only works on 100Mbps ports and faster. As such, if your switch only has 10 Mbps ports available, using […]

Setting up VLANs on a single switch is relatively simple. First you define different VLANs, and then make ports members of those VLANs. However, when you interconnect or link switches across a network (referred to as trunking), you’ll need a way for switches to know on what VLAN a frame belongs. There are two main […]

VLAN membership can be configured in two different ways, known as static and dynamic.
Static VLANs. With a static VLAN, an administrator defines VLANs on a switch and then assigns ports to them. This is the most common way in which VLANs are configured.
Dynamic VLANs. A dynamic VLAN is one in which a switch port […]

The main benefits of using VLANs are that they provide increased flexibility, scalability, and security.
Flexibility. Because a VLAN assigns a user to a broadcast domain based on the port their system is plugged into, additions, moves, and changes are made simple. If you wanted a user to be moved to a different broadcast domain, all […]