What is super VLAN?

Dear friend!

VLANs can be classified into different types based on the application scenario.

For example, according to different levels, the levels can be classified into the following:

1. Port-based VLAN (also called physical VLAN and one-layer VLAN)

2. MAC address-based VLAN (also called Layer 2 VLAN)

3. Protocol-based VLAN (also called Layer 3 VLAN)

According to the network layer of the packet transport network, VLANs are classified into the following types:

1. C-VLAN indicates the customer-side VLAN.

2. S-VLAN indicates the supplier-side VLAN.

More details: What is the difference between VLAN, C-VLAN, and S-VLAN.

VLAN aggregation introduces the concept of sub-VLANs and super-VLANs：

1. Sub-VLAN: contains only physical interfaces, and is used to isolate broadcast domains. A sub-VLAN cannot be used to create a Layer 3 VLANIF interface. Hosts in each sub-VLAN use the VLANIF interface of the associated super-VLAN for Layer 3 communication with external devices.

2. Super-VLAN: contains no physical interfaces, and is used only for creating a Layer 3 VLANIF interface. The VLANIF interface remains Up providing that at least one physical interface in any associated sub-VLAN is Up. A super-VLAN can contain one or more sub-VLANs, which use its IP address as their subnet gateway.

In a super-VLAN, each host, no matter which sub-VLAN it belongs to, is allocated an IP address from the subnet segment associated with the super-VLAN (a sub-VLAN does not occupy an independent subnet). Therefore, sub-VLANs share the same gateway.

More details: What Is Super VLAN?

Thank you!

Types of Virtual LAN (VLAN)

Virtual LAN (VLAN) is created on Layer 2 switch to reduce the size of broadcast domain. It is one of the technologies used to improve network performance by the separation of large broadcast domains into smaller ones.

There are 5 main types of VLANs depending on the type of the network they carry:

1.            Default VLAN –

When the switch initially starts up, all switch ports become a member of the default VLAN (generally all switches have default VLAN named as VLAN 1), which makes them all part of the same broadcast domain. Using default VLAN allows any network device connected to any of the switch port to connect with other devices on other switch ports. One unique feature of Default VLAN is that it can’t be rename or delete.

2.            Data VLAN –

Data VLAN is used to divide the whole network into 2 groups. One group of users and other group of devices. This VLAN also known as a user VLAN, the data VLAN is used only for user-generated data. This VLAN carrying data only. It is not used for carrying management traffic or voice.

3.            Voice VLAN –

Voice VLAN is configured to carry voice traffic. Voice VLANs are mostly given high transmission priority over other types of network traffic. To ensure voice over IP (VoIP) quality (delay of less than 150 milliseconds (ms) across the network), we must have separate voice VLAN as this will preserve bandwidth for other applications.

4.            Management VLAN –

A management VLAN is configured to access the management capabilities of a switch (traffic like system logging, monitoring). VLAN 1 is the management VLAN by default (VLAN 1 would be a bad choice for the management VLAN). Any of a switch VLAN could be define as the management VLAN if admin as not configured a unique VLAN to serve as the management VLAN. This VLAN ensures that bandwidth for management will be available even when user traffic is high.

5.            Native VLAN –

This VLAN identifies traffic coming from each end of a trunk link. A native VLAN is allocated only to an 802.1Q trunk port. The 802.1Q trunk port places untagged traffic (traffic that does not come from any VLAN) on the native VLAN. It is a best to configure the native VLAN as an unused VLAN.

What is super VLAN?

VLAN aggregation, also called super-VLAN, partitions a broadcast domain into multiple VLANs (sub-VLANs) on a physical network and aggregates the sub-VLANs into a single logical VLAN (super-VLAN). The sub-VLANs use the same IP subnet and default gateway address, so the number of IP addresses used is reduced

What Are Application Scenarios of Super VLAN?

In the following figure, an enterprise has multiple departments that connect to the Internet through different switches. For security purposes, the enterprise adds different departments to different VLANs. However, the number of available IP addresses is limited.

The requirements are as follows:

·         All departments require access to the Internet.

·         Department 1 and department 2 need to communicate with each other.

·         Department 3 and department 4 need to communicate with each other.

Layer 2 communication between hosts in sub-VLANs and on an external network

VLAN aggregation and proxy ARP can be used to meet the preceding requirements. Deploy super-VLAN 2 and super-VLAN 3 on the switch and add sub-VLAN 21 and sub-VLAN 22 to super-VLAN 2 and sub-VLAN 31 and sub-VLAN 32 to super-VLAN 3. After IP addresses are assigned to super-VLAN 2 and super-VLAN 3 on the switch, users in department 1 and department 2 can access the Internet using the IP address of super-VLAN 2, and users in department 3 and department 4 can access the Internet using the IP address of super-VLAN 3.

Therefore, VLAN aggregation allows all departments to access the Internet access and conserves IP addresses.

To allow communication between departments 1 and 2 and departments 3 and 4, configure proxy ARP on the switch in super-VLAN 2 and super-VLAN 3.

Very Good demonstration by @liqiang185, just want to add some celebration

On a physical network, VLAN aggregation, also known as super-VLAN, it divides a broadcast domain into numerous VLANs (sub-VLANs) and aggregates the sub-VLANs into a single logical VLAN (super-VLAN). The number of IP addresses utilised is minimized since the sub-VLANs share the same IP subnet and default gateway address.

The super-VLAN and sub-VLAN are different from common VLANs that contain a Layer 3 logical interface and multiple physical interfaces.

• Sub-VLAN: contains only physical interfaces, and is used to isolate broadcast domains. A sub-VLAN cannot be used to create a Layer 3 VLANIF interface. Hosts in each sub-VLAN use the VLANIF interface of the associated super-VLAN to communicate with external devices over Layer 3.

• Super-VLAN: is only used for creating a Layer 3 VLANIF interface and contains no physical interfaces. Its IP address is used as the subnet gateway. A VLANIF interface in a super-VLAN is Up as long as a physical interface in any associated sub-VLAN is Up. This is unlike a VLANIF interface, which is Up as long as a physical interface is Up.