Enterasys Networks 802.1Q manual Virtual Local Area Networks, Defining VLANs

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Virtual Local Area Networks

This chapter introduces the concepts of Virtual Local Area Networks (VLANs) and discusses the central concepts of IEEE 802.1Q VLANs. This chapter also contains information on how to contact Enterasys Networks for additional support related to VLANs.

1.1DEFINING VLANs

A Virtual Local Area Network is a group of devices that function as a single Local Area Network segment (broadcast domain). The devices that make up a particular VLAN may be widely separated, both by geography and location in the network.

The creation of VLANs allows users located in separate areas or connected to separate ports to belong to a single VLAN group. Users that are assigned to such a group will send and receive broadcast and multicast traffic as though they were all connected to a common network. VLAN aware switches isolate broadcast, multicast, and unknown traffic received from VLAN groups, so that traffic from stations in a VLAN are confined to that VLAN.

When stations are assigned to a VLAN, the performance of their network connection is not changed. Stations connected to switched ports do not sacrifice the performance of the dedicated switched link to participate in the VLAN. As a VLAN is not a physical location, but a membership, the network switches determine VLAN membership by associating a VLAN with a particular port or frame type.

Figure 1-1shows a simple example of a port based VLAN. Two buildings house the Sales and Finance departments of a single company, and each building has its own internal network. The stations in each building connect to a SmartSwitch in the basement. The two SmartSwitches are connected to one another with a high speed link.

Virtual Local Area Networks 1-1

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Contents 802.1Q Vlan User’s Guide Page Page Page Contents Iv Contents Figures Tables Structure of this Guide Using this GuideDocument Conventions Related DocumentsDefining VLANs Virtual Local Area NetworksExample of a Vlan Types of VLANsBenefits and Restrictions 1 802.1Q VLANsSecureFast VLANs Other Vlan StrategiesVlan ID Vlan TermsGeneric Attribute Registration Protocol Garp Your email address Getting HelpVlan Components DescriptionCustomizing the Vlan Forwarding List Configuration ProcessDefining a Vlan Classifying Frames to a VlanInside the Switch Vlan Switch OperationBroadcasts, Multicasts, and Unknown Unicasts Receiving Frames from Vlan PortsForwarding Decisions Known Unicasts Garp Switch OperationPage Switch Without VLANs Managing the SwitchSwitch Management with Only Default Vlan Switch with VLANsSwitch Management with VLANs 802.1Q Vlan Screen Hierarchy Summary of Vlan Local ManagementWhen to Use 802.1Q Vlan Configuration Menu ScreenMenu Definitions How to AccessScreen Example Device Vlan Configuration Screen Device Vlan Configuration Screen Toggle Field DefinitionsVlan Name lower part Renaming a Vlan Changing the Vlan to FID AssociationDisabling VLANs Deleting a VlanEnabling VLANs Paging Through the Vlan List Changing the Forwarding ModePort Assignment Configuration Screen Port Assignment Configuration ScreenPort Mode Changing the Port ModeAssigning a Vlan ID Paging Through the Port List Port Filtering Configuration ScreenSee the names of the VLANs associated with the Vlan ID. If a Displaying Vlan IDs Associated with a Port Filter Using VlanSelecting the Type of Filtering for a Port Vlan Forwarding Configuration ScreenPort Type Adding Forwarding List Entries Viewing Current Vlan PortsPaging Through Vlan Forwarding List Entries Changing the Frame Format Deleting Forwarding List EntriesProtocol Vlan Configuration Screen Protocol Vlan Configuration ScreenVlan ID Protocol Type Ether type Assigning a Protocol Family to a Vlan ID28VLAN Configuration Displaying the Protocol Types on Current Ports Protocol Ports Configuration Screen10 Protocol Ports Configuration Screen Delete ALL Adding/Deleting Ports Associated with a Vlan IDQuick Vlan Walkthrough 32VLAN Configuration11 Walkthrough Stage One 12 Walkthrough Stage Two Test Vlan 14 Walkthrough Stage Four 15 Final Walkthrough Stage Page Examples Example 1, Single Switch OperationSwitch Configured for VLANs Solving the ProblemFrame Handling Example 2, VLANs Across Multiple SwitchesExample 2, VLANs Across Multiple Switches Switch Bridge 1 Broadcasts Frames Transmitting to Switch Transmitting to Bridge Example 3, 1D Trunk Connection to 802.1Q Vlan NetworkExample 3, 1D Trunk Connection to 802.1Q Vlan Network Switch 4 is set as follows Frame Handling Switch 2 Forwards to 1Q Trunk 10 Switch 1 Forwards to 1D Trunk Example 4, Isolating Network Traffic According to Protocol 11 Example 4, Isolating Traffic According to Protocol 16Examples Example 4, Isolating Network Traffic According to Protocol 18Examples Numerics IndexIndex-2 Index-3

802.1Q specifications

Enterasys Networks, a subsidiary of the Siemens Group, is widely recognized for its comprehensive networking solutions, with a strong emphasis on security, reliability, and performance. One of the key technologies offered by Enterasys is 802.1Q, a critical component of Ethernet networking that establishes standards for VLAN (Virtual Local Area Network) tagging. This technology is essential for enhancing network performance and managing traffic efficiently.

The primary feature of 802.1Q is its ability to create VLANs, which segment a physical network into multiple logical networks. This segmentation improves network security by isolating sensitive data and restricting access to specific users or devices. With VLANs, organizations can reduce broadcast traffic, thereby enhancing overall network efficiency. Different departments within an organization can operate on their own VLAN, ensuring that their traffic is kept separate from others.

One significant technological aspect of 802.1Q is its tagging method. When a frame passes through a switch port configured for IEEE 802.1Q, the switch appends a VLAN tag to the frame. This tag contains important information, such as the VLAN ID, enabling switches and devices throughout the network to identify which VLAN the frame belongs to. This tagging is especially critical in environments where multiple VLANs share the same physical infrastructure.

Another characteristic of Enterasys Networks' implementation of 802.1Q is interoperability with existing network standards and protocols. This means that organizations can implement VLAN tagging without requiring major upgrades or replacements of their switch hardware. Enterasys ensures that its switches are compliant with various industry standards, making it easier for enterprises to integrate these solutions into their existing network settings.

Security is another vital feature of Enterasys Networks’ 802.1Q offering. By leveraging VLANs, organizations can enforce stricter access controls and policies, reducing the risk of unauthorized access to sensitive network segments. This is particularly beneficial for industries with stringent compliance requirements, such as finance and healthcare.

In summary, Enterasys Networks' 802.1Q technology plays a pivotal role in modern networking by facilitating VLAN creation, enabling efficient traffic management, ensuring interoperability, and bolstering network security. As organizations increasingly rely on connected devices and data-driven processes, technologies like 802.1Q are essential for building robust, scalable, and secure networking environments.
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