Shulou(Shulou.com)06/02 Report--

Basic concept and Experimental Verification of VLAN

I. the concept and advantages of VLAN

VLAN, that is, virtual local area network (virtual Local Area Network), first of all, why do we introduce VLAN?

We consider such a situation: in the traditional switched Ethernet, all users are in the same broadcast domain, when the scale of the network is large, the number of broadcast packets will increase sharply, which will greatly affect the efficiency of network transmission, especially when a network equipment fails and constantly sends broadcasts to the network, it will lead to a broadcast storm and paralyze network communication. So we need to split the broadcast domain to solve this problem. Let's first introduce how to split the broadcast domain:

Split broadcast domain

1. Physical segmentation: physically divide the network into several small networks and then connect the different networks (such as routers) with routing devices that can isolate broadcasts.

Implement communication, but the disadvantage is also obvious: lack of flexibility

two。 Logical segmentation: divide multiple VLAN, each VLAN is a broadcast domain, a VLAN corresponds to multiple interfaces; it works in the data link layer.

Advantages of VLAN:

Control broadcast

Enhance network security

Simplify network management

II. Types of VLAN

Static VLAN

Static VLAN is divided based on port. Features: a VLAN can contain multiple ports, but a port belongs to only one VLAN.

Dynamic VLAN

Based on MAC address division

Experimental environment:

1.GNS3 software

2.3initialized PC hosts + 1 initialized switch

3. If the host is using a virtual machine, then all the firewalls of the virtual machine need to be turned off, otherwise the data transmission will be affected later.

The process of the experiment:

1.GNS3 software, 3 PC hosts + 1 switch ready

two。 We connect them all with a network cable, and define each IP address according to our personal preference. PC2 and PC3 are written in the same VLAN next to the port, so it is convenient for us to enter the IP address and check it.

3. Create VLAN

Remember to turn off routing kinetic energy in global mode before creating a VLAN.

4. Add the switch port to the corresponding VLAN

Show vlan-switch brief to view VLAN information (abbreviated: show vlan-sw b)

Access: the access link can only run the corresponding VLAN data (direct access to the terminal (PC)).

5. Create multiple ports in the switch

Enter the View VLAN instruction

VLAN has all created the port f1max 0 of PC1 in VLAN10. The ports for PC2 and PC3 are in VLAN20.

Experimental purpose:

VLAN is a virtual interface, because there are multiple physical interfaces in VLAN, which VLAN your port belongs to, you are in that broadcast domain.

VLAN cannot be crossed, can not be crossed and crossed.

So let's see if PC2 and PC3 can communicate with each other in the same VLAN, and whether pc2 and pc1 can communicate with each other in different VLAN.

Found that PC2 and PC3 can communicate with each other.

PC2 and PC1 are not in the same VLAN and cannot communicate with each other

Therefore, in VLAN, only the same VLAN can be interoperable. PC in the same VLAN can no longer communicate with each other.

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