H3C Technologies H3C WX3000 Series Unified Switches - Manual (Page 78)

10-5
Port-Based VLAN
Port-based VLAN technology introduces the simplest way to classify VLANs. You can assign the ports
on the device to different VLANs. Thus packets received on a port will be transmitted through the
corresponding VLAN only, so as to isolate hosts to different broadcast domains and divide them into
different virtual workgroups.
The link type of a port on the device can be one of the following: access, trunk, and hybrid. For the three
types of ports, the process of being added into a VLAN and the way of forwarding packets are different.
For details, refer to Port Basic Configuration in H3C WX3000 Series Unified Switches Switching Engine
Configuration Guide .
Port-based VLANs are easy to implement and manage and applicable to hosts with relatively fixed
positions.
Protocol-Based VLAN
Introduction to Protocol-Based VLAN
Protocol-based VLAN is also known as protocol VLAN, which is another way to classify VLANs.
Through the protocol-based VLANs, the switch can analyze the received packets carrying no VLAN tag
on the port and match the packets with the user-defined protocol template automatically according to
different encapsulation formats and the values of specific fields. If a packet is matched, the switch will
add a corresponding VLAN tag to it automatically. Thus, data of specific protocol is assigned
automatically to the corresponding VLAN for transmission.
This feature is used for binding the types of services provided in the network to VLANs to facilitate
management and maintenance.
Encapsulation Format of Ethernet Data
This section introduces the common encapsulation formats of Ethernet data for you to understand well
the procedure for the switch to identify the packet protocols.
Ethernet II and 802.2/802.3 encapsulation
Mainly, there are two encapsulation types of Ethernet packets: Ethernet II and 802.2/802.3, defined by
RFC 894 and RFC 1042 respectively. The two encapsulation formats are described in the following
figures.
z
Ethernet II packet:
Figure 10-4 Ethernet II encapsulation format
DA&SA(12) Type(2) Data
z
802.2/802.3 packet:
Figure 10-5 802.2/802.3 encapsulation format
DA&SA(12) Length(2) Data DSAP(1) SSAP(1) Control(1) OUI(3) PID(2)