A few basic concepts:
1 refers to the internal switch port to send out the transmission
2. Data frame processing internal switch, all with vlan etag
3. Port marking or to label (tag or untag) is in terms of output port
Three types of ports on the switch patterns:
Three types of ports the switch mode Access, Hybrid and understanding Trunk
There are three types of link Ethernet port: Access, Hybrid and Trunk.
Access type of port can belong to one VLAN, ports for connecting PCs;
Trunk port can allow multiple VLAN, can receive and transmit packets of a plurality of VLAN, ports between switches generally used;
Hybrid port can allow multiple VLAN, can receive and transmit packets of a plurality of VLAN, the switch can be used to connect and to be connected to a computer user.
Hybrid and Trunk port when data is received, the processing method is the same, the only difference is that the transmission data: Hybrid port allows multiple VLAN packets without tags send, and Trunk port only allows the default VLAN the message is sent without tags.
Here we must first clarify the concept of the default VLAN ports
Access port only belongs to one VLAN, its default VLAN is it in the VLAN, do not set;
Hybrid and Trunk port belonging to a plurality of the VLAN, a need to set the default VLAN ID. By default, Hybrid ports and Trunk default VLAN is VLAN 1
When the port receives packets without VLAN Tag, and the packet is forwarded to the port (if the default setting of the port VLAN ID) belongs to the default VLAN. When sending the packet with VLAN Tag, the same packet if the port VLAN ID is the default VLAN ID, the system will remove the packet VLAN Tag, and then sends the packet.
NOTE: For Huawei switches default VLAN is called "Pvid Vlan", Cisco switches to the default VLAN is called "Native Vlan" data processing interface to switch out as follows:
Acess port that receives the packet:
Receives a packet, determine whether VLAN information: If you have not marked PVID port, and exchange forwards, if there are directly discarded (default)
Acess packet transmitter port (sent out from the inside of the switch):
The release the VLAN information, sent directly
(Therefore, Access ports can communicate on the same host at the same VLAN switch; may also be implemented when the default packet switching VLAN1 cascaded switch, but can not achieve VLAN transparent transmission.)
trunk port that receives the packet:
It receives a packet, determine whether VLAN information: If you have to determine whether to allow the trunk port VLAN to enter the data: If you can then forwarded, or discarded; if no VLAN information. PVID is marked, and exchanged forward.
trunk port transmitters text:
Comparison will send packets PVID VLAN information and the port, if not equal, direct send. If it is equal, the release VLAN information, and then transmitted.
(Therefore, the switch is set to level even all Trunk port and allows all the VLAN through, VLAN2-VLAN4000 directly and transparently, and because VLAN1 is the default and Trunk same PVID need to add VLAN information and VLAN information by peeling achieved passthrough and if to change the default Trunk PVID, VLAN-Y can be achieved under communication at a certain VLAN-X switch and another switch.)
hybrid port that receives the packet:
Receives a packet, determine whether VLAN information: If there is, it is determined whether the hybrid port allows the data VLAN entry: If you can then forwarded, or discarded (this time untag port configuration is not taken into account, the configuration untag only works for sending messages);
If not then marked PVID port, and exchange forwards.
hybrid port transmitters text:
1, it is determined that the attribute of the local port in the VLAN (disp interface to the port to see which is the untag VLAN, which is VLAN tag)
2, if the release untag VLAN information, retransmission, if a tag is sent.
(Therefore, Hybrid Host enables communication at different VLAN.)