VLAN
One VLAN = one broadcast domain = logical network segment (subnet)
Each logical VLAN acts like a separate physical bridge
Each port on the switch can be assigned to a different VLAN
By default, all ports belong to VLAN1 (Cisco)
Each logical VLAN acts like a separate physical bridge
The same VLAN can span multiple switches
Backbone function supports data from multiple VLANs
The trunk uses a special encapsulation format to support different VLANs
Only Fast Ethernet ports can be configured as trunk ports
There are two protocols for VLAN tagging of frames by switches: ISL and 802.1Q
The trunking function of ISL allows VLAN information to traverse the trunk line
Realized by hardware (ASIC)
The ISL logo does not appear on the workstation, and the client does not know the ISL encapsulation information
Between switches or routers and switches, between switches and servers with ISL network cards can be implemented
IEEE Common Frame Marking Protocol 802.1Q
If you want to create multiple VLANs across cisco switches and switches from other manufacturers, you must use the 802.1Q protocol
VTP protocol (VLAN Trunking Protocol)
An information system that can announce VLAN configuration information
Maintain consistency of VLAN configuration information through a common management domain
VTP can only send the information to be announced on the trunk port
Supports mixed media backbone connections (Fast Ethernet, FDDI, ATM)
VTP principle: The core switch publishes learning information - the sub-switches learn the VLAN configuration of the main switch
How VTP works
How VTP works:
Do a good job of VLAN configuration information on the core switch, and then synchronize it to other sub-switches.
There are no working scenarios using VTP,
For example, in a large enterprise with more than 1,000 switches, each additional VLAN needs to be configured on more than 1,000 switches. Wouldn't it be a waste of time to configure?
Working scenarios using VTP,
With VTP, it is different. As long as the network administrator adds/deletes VLANs on the core switch, VTP will automatically synchronize this information to other switches.
VTP cuts
VTP cut instructions:
The working scenario before cutting with VTP:
When user A needs to send data to user B, user A needs to go from switches 1 to 6 to ask where user B is, until switch 4 gets a response and informs it on port 2, so that user A can communicate with user B. data exchange.
It is conceivable that the process in the middle is complicated and tedious, and it takes a lot of time. If each computer broadcasts data like this before sending data, in a local area network with thousands of computers, the switch will not be exhausted. Therefore, Great network experts developed VTP technology.
The working scene after cutting with VTP:
It is stipulated in the VTP protocol that when computer A sends a data packet to computer B, only the switch of the VLAN corresponding to computer B will receive the broadcast. Taking the above topology diagram as an example, only switch 4 has the corresponding VLAN. No matter how many broadcasts are sent by A, only switch 4 will receive the broadcasts and respond. Other switches simply ignore the broadcast from A, so as to achieve VTP reduction, reduce time, and improve efficiency.