Vlan types – H3C Technologies H3C WX3000E Series Wireless Switches User Manual
Page 24
14
In the header of a traditional Ethernet data frame, the field after the destination MAC address and the
source MAC address is the Type field indicating the upper layer protocol type, as shown in
.
Figure 3 The format of a traditional Ethernet frame
IEEE 802.1Q inserts a four-byte VLAN tag after the DA&SA field, as shown in
.
Figure 4 The position and format of VLAN tag
A VLAN tag comprises the following fields: tag protocol identifier (TPID), priority, canonical format
indicator (CFI), and VLAN ID.
•
The 16-bit TPID field with a value of 0x8100 indicates that the frame is VLAN-tagged.
•
The 3-bit priority field indicates the 802.1p priority of the frame.
•
The 1-bit CFI field specifies whether the MAC addresses are encapsulated in the standard format
when packets are transmitted across different media. A value of 0 indicates that MAC addresses
are encapsulated in the standard format; a value of 1 indicates that MAC addresses are
encapsulated in a non-standard format. The value of the field is 0 by default.
•
The 12-bit VLAN ID field identifies the VLAN the frame belongs to. The VLAN ID range is 0 to 4095.
As 0 and 4095 are reserved, a VLAN ID actually ranges from 1 to 4094.
A network device handles an incoming frame depending on whether the frame is VLAN tagged and the
value of the VLAN tag, if any. For more information, see "
Introduction to port-based VLAN
NOTE:
•
The Ethernet II encapsulation format is used here. Besides the Ethernet II encapsulation format, other
encapsulation formats, including 802.2 LLC, 802.2 SNAP, and 802.3 raw, are also supported by
Ethernet. The VLAN tag fields are also added to frames encapsulated in these formats for VLAN
identification.
•
For a frame with multiple VLAN tags, the device handles it according to its outer-most VLAN tag and
transmits its inner VLAN tags as payload.
VLAN types
You can implement VLANs based on the following criteria:
•
Port
•
MAC address
•
Protocol
•
IP subnet
•
Policy
•
Other criteria
- H3C WX5500E Series Access Controllers H3C WX3500E Series Access Controllers H3C WX2500E Series Access Controllers H3C WX6000 Series Access Controllers H3C WX5000 Series Access Controllers H3C LSWM1WCM10 Access Controller Module H3C LSUM3WCMD0 Access Controller Module H3C LSUM1WCME0 Access Controller Module H3C LSWM1WCM20 Access Controller Module H3C LSQM1WCMB0 Access Controller Module H3C LSRM1WCM2A1 Access Controller Module H3C LSBM1WCM2A0 Access Controller Module H3C WA3600 Series Access Points H3C WA2600 Series WLAN Access Points