Shulou(Shulou.com)06/03 Report--

VLAN and layer 3 switches to learn:

The concept and advantages of 1.VLAN

Types of 2.VLAN

3. Configuration of static VLAN

Introduction and configuration of 4.Trunk

5. Forwarding principle and configuration of layer 3 switch

I. the concept and advantages of VLAN

In traditional switched Ethernet, all users are in the same broadcast domain. When the network is large, the number of broadcast packets will increase sharply, and when the number of broadcast packets accounts for 30% of the total, the transmission efficiency of the network will decrease significantly. Especially when some network equipment breaks down, it will keep sending broadcasts to the network, which leads to the broadcast storm and paralyzes the network communication. So, how should we solve the problems? We can solve this problem by separating broadcast domains, and there are two ways to separate broadcast domains.

Physical separation. The network is physically divided into several small networks, and then different networks are connected to achieve communication using routing devices that can isolate broadcasts.

two。 Logical separation. The network is logically divided into several small virtual networks, namely VLAN. VLAN works at the data link layer of the OSI reference model. A VLAN is a switched network, in which all users are in the same broadcast domain, and each VLAN communicates through routing devices. The use of physical separation has many disadvantages, which will make the design of the local area network inflexible.

As shown in the figure:

VLAN has the characteristics of flexibility and expansibility, so the advantages of VLAN are:

1. Control broadcast

two。 Enhance network security

3. Simplify network management II. Types of VLAN

(1) static VLAN is port-based VLAN, which is the most common way to implement VLAN at present. Static VLAN specifies which VLAN the switch port belongs to, which needs to be manually configured by the network administrator

Devices in the same VLAN can communicate with each other, but different VLAN cannot.

(2) dynamic VLAN

Dividing dynamic VLAN based on MAC address

Range of VLAN

3. Steps to configure static VLAN:

1. Create VLAN

two。 Add the switch port to the corresponding VLAN

3. Verify the configuration of VLAN

There are two ways to create a VLAN

1.VLAN database configuration mode (in privileged mode)

two。 Global configuration mode

3. Create a VLAN example

4. Delete VLAN

5. Add Port to VLAN

6. Join multiple ports to VLAN at the same time

7. Restore the interface to the default configuration state

8. Verify the configuration of VLAN

For an example of VLAN configuration, see the later experimental case!

Https://blog.51cto.com/14481836/2428075

IV. Introduction and configuration of Trunk

What is Trunk?

In a switched network, there are two types of links:

① access link: usually belongs to a VLAN.

② intermediate link: can carry multiple VLAN. (all VLAN information can be run on the trunk link)

So the function of Trunk is to enable the same VLAN to communicate across the switch.

Identification of VLAN

As shown in the figure:

There are two general types of logos:

1.ISL (Cisco Private Standard) 30 bytes

2.IEEE 802.1q 4 byt

The configuration of TRUNK, as shown below:

It should be noted that: Ethernet channel: at least two or more links are required, and the port must be Trunk

Features: increase link bandwidth

Increase link reliability

The configuration case of TRUNK will be released later in the lab! You can operate with it!

Fifth, forwarding principle and configuration of layer 3 switch

Three-layer switching technology

The principle of layer 3 switching

Virtual interface of layer 3 switch

Virtual interface acts as host gateway

Configuration of layer 3 switch

The next release of the experimental case of layer 3 switch!

Summary Overview:

The emergence of 1.VLAN adds flexibility to the design of the local area network, so that the network administrator is no longer limited to the physical location of the user when dividing the working group.

The purpose of 2.Trunk is to enable the same VLAN to communicate across switches.

3. Layer 3 switches switch and route packets through hardware. To put it simply, layer 3 switching is equal to layer 2 switching plus layer 3 forwarding.

4. Layer 3 switches have routing functions, so VLAN can access each other, and each VLAN virtual interface is the gateway of that segment.

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