Example 2, VLANs Across Multiple Switches

2.A Port VLAN ID is assigned to each port (1 and 3) as follows using the Port Assignment screen:

Port 1, VLAN ID: 223 for the Blue VLAN

Port 3, VLAN ID: 222 for the Red VLAN

These settings change the configuration of the switch, so that Port 1 is part of Blue VLAN, Port 3 is part of Red VLAN, and both are set as frame type of untagged.

3.Port 2 is configured as a 1Q Trunk port as follows using the Port Assignment Configuration screen:

Port 2, Port Mode: 1Q Trunk

Port 2 is set as an 802.1Q Trunk port, which makes its Port VLAN List contain all VLANs and sets all frames forwarded out this port as tagged frames. This completes the transmission path between Switch 4 and Switch 2.

4.2.2Frame Handling

The following describes how, when User A attempts to log on to the File Server on Bridge 4, the frames from User A are classified on Switch 4 and traverse the network. In this example, the MAC address of User A is “Y” and the MAC address for the File Server is “Z”. The following description includes illustrations to help understand how the frames flow through the network.

1.User A sends a frame with a Broadcast Destination Address in an attempt to locate the File Server. The frame is received on User A’s port of Bridge 1 and, because the frame is a broadcast frame, it is transmitted out all ports of Bridge 1 as shown in Figure 4-4.

Figure 4-4 Bridge 1 Broadcasts Frames

Redco

 

 

 

Blue Industries

User A

Bridge 1

 

2

Bridge 2

1

4 3

 

Red VLAN

Blue VLAN

 

 

 

4

 

Floor 4

 

 

 

 

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4-6Examples

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Enterasys Networks 802.1Q manual Bridge 1 Broadcasts Frames

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.