VLAN trunking is an efficient way to configure your network to help your data flow as efficiently as possible — but how does it actually work? Novotech has the answers.
What is VLAN Trunking? Let us explain.
In our data-rich world, it's common to find networks needing more efficient transmission capacity than what one-to-one links can provide. Engineers and admins must use switches, ports, and routers to design robust networks that can carry data inputs to their desired destination with minimal disruption to the end users they serve. One of their most valuable tools is VLAN trunking.
Just as a tree trunk links multiple branches into a single unit, VLAN trunking serves to tie a vast number of devices together into one coherent network. This efficient principle of network design is critical for systems that support many devices, so we'll dive deeper into what exactly VLAN trunking is, how it works, and what hardware can help you integrate it into your architecture.
What Is VLAN Trunking?
To understand what VLAN trunking is, it helps to define LAN and VLAN.
Short for local area network, LAN refers to the network of connected devices occupying physical space, like a school, office, or some other building. By contrast, a virtual local area network (VLAN) refers to the cluster of devices linked to the same virtual network, whether or not they occupy the same physical space.
The distinction is important because VLANs allow admins to configure their networks by parameters other than space. For example, an R&D department may share data unsuitable for the sales department to view, so segmenting networks by department or some other criteria can be a helpful way to transmit data more efficiently and securely.
VLAN trunking ties together multiple VLANs to a single port to connect multiple subnets to a network. This capability eliminates the need for each VLAN to be connected individually into a port since they're already tied into the trunk, but it has another advantage too. By assigning switches and creating logical groups to partition communications, admins prevent broadcast frames from unnecessarily transmitting to devices that don't need them.
In these ways, VLAN trunking filters out the "noise" of overlap during data transmission, freeing up more bandwidth so that data can be sent more efficiently. By consolidating multiple VLAN devices and removing the overlap between those that don't need to communicate, VLAN trunking makes for a cleaner network design.
How Does VLAN Trunking Work?
VLAN trunking is a helpful tool in streamlining IT and communication architectures, and integrating them into your network can significantly improve its efficiency and security. You'll need the proper hardware to take advantage of the benefits that VLAN trunking has to offer, like:
- VLAN-capable routers like the EdgeRouter800 with WiFi, Global.
- Switches like the NT24K-AC1-DC1 Modular Managed Ethernet Switch or the SLX-8MS 8 Port Managed Ethernet Switch.
Other than hardware, three components are involved in making VLAN trunking work:
- Proper proprietary protocols
- Tagging
- Access ports
Below we'll look at all three components in more detail.
Proprietary Protocols
Developers and engineers use a series of rules and standards known as protocols to transmit data across their networks, and there are three VLAN trunking protocols in use today. Those protocols include the Dynamic Trunking Protocol (DTP), Inter-Switch Link (ISL), and IEEE 802.1Q.
Dynamic Trunking Protocol (DTP)
For VLAN trunking to work properly, each port must be designated as a trunk or access port. We'll go into the difference later, but configuring each of the many switch ports present in VLAN networks today can be time-consuming. Therefore, DTP simplifies the process by creating an arrangement to which each one can default until otherwise configured by the admin.
All Cisco-powered switch ports are initially set to dynamic auto as their operational state. This setting causes each switch port to be designated as a trunk or access port based on the state of the other port to which it's connected. In other words, if SW1 is designated as a trunk or access port connected to SW2, SW2 will detect the state of SW1 and become a trunk or access port as needed.
Ports can be configured to settings other than dynamic auto, and DTP is the framework that makes it all possible.
Inter-Switch Link (ISL)
As its name implies, this Cisco-patented VLAN trunking protocol creates a single link from one port to another instead of multiple ports simultaneously. It's proprietary, used only for Cisco switches, and can be applied to Fast Ethernet and Gigabit Ethernet connections. It's largely been replaced by the more popular IEEE 802.1Q protocol. Still, DTP prioritizes ISL over IEEE 802.1Q whenever it contacts both unless one of the switches lacks it.
IEEE 802.1Q
Also known as Dot1q, the IEEE developed this protocol for VLANs on an 802.3 Ethernet connection. It's become the primary standard in use today, and it employs a system of frames that it tags by a given rule set to decide how a switch should handle them. With this rule in place, switches may efficiently transmit data to their desired destination according to the tagging system it receives.
Tagging
The IEEE 802.1Q assigns a tagging frame that consists of four components. They are:
- A 16-bit tag protocol identifier (TPID) distinguishes the tagged VLAN frame from untagged ones outside the network.
- A 3-bit priority code point (PCP) explains the Class of Service (CoS) service level and corresponds to the level of traffic.
- A 1-bit drop eligible indicator (DEI) signifies whether or not the frame can be dropped in the event of access traffic.
- A 12-bit VLAN Identifier (VID), which ranges from 0–4,095, assigns a number to that specific VLAN.
More precisely, the PCP, DEI, and VID are all subparts of a larger 16-bit field known as tag control information or TCI. Therefore, the IEEE 802.1Q tagging system can be thought of as containing two components — the TPID and the TCI — with the latter containing three components of its own.
Trunk Ports and Access Ports
With the tagging system in place, access and trunk ports can be configured to send data from one VLAN to another, and the type of port you use can significantly impact network design.
The simpler of the two access ports links one switch to an individual VLAN. That allows VLAN devices to receive untagged frames without losing signal quality. Still, the one-to-one correspondence makes access ports less scalable when networks become even remotely complex.
Unlike access ports, trunk ports connect a single switch to multiple VLANs, allowing for greater network complexity. Since data is transmitted across multiple VLANs, they require tagging, but trunk ports also give networks higher bandwidth and lower latency.
Stay Connected With Novotech
For environments where many devices are linked to a single system, VLAN trunking is an efficient way to improve data transmission and enhance the overall quality of your network. It takes the proper hardware and a bit of IT know-how to implement it, but once you do, greater bandwidth. reduced latency and improved security are a few benefits you can enjoy.
At Novotech, we supply you with the IoT hardware you need for even the most complex network designs. We offer a wide range of routers, boosters, switches, antennas, and more, so check out our inventory today and see how we can help you connect.