Operation Manual – VLAN
H3C S3610&S5510 Series Ethernet Switches
Chapter 1 VLAN Configuration
1-3
The VLAN Tag comprises four fields: the tag protocol identifier (TPID) field, the Priority
field, the canonical format indicator (CFI) field, and the VLAN ID field.
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The TPID field, 16 bits in length and with a value of 0x8100, indicates that a packet
carries a VLAN tag with it.
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The Priority field, three bits in length, indicates the 802.1p priority of a packet. For
information about packet priority, refer to the
QoS
part of the manual.
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The CFI field, one bit in length, specifies whether or not the MAC addresses are
encapsulated in standard format when packets are transmitted across different
medium. With the field set to 0, MAC addresses are encapsulated in standard
format; with the field set to 1, MAC addresses are encapsulated in non-standard
format. The filed is 0 by default.
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The VLAN ID field, 12 bits in length and with its value ranging from 0 to 4095,
identifies the ID of the VLAN a packet belongs to. As VLAN IDs of 0 and 4095 are
reserved by the protocol, the value of this field actually ranges from 1 to 4094.
A network device determines the VLAN to which a packet belongs to by the VLAN ID
field the packet carries. The VLAN Tag determines the way a packet is processed. For
more information, refer to section
Introduction to Port-Based VLAN
.
Note:
The frame format mentioned here is that of Ethernet II. Besides Ethernet II
encapsulation, other types of encapsulation, including 802.2 LLC, 802.2 SNAP, and
802.3 raw are also supported by Ethernet. The VLAN tag fields are also added to
packets adopting these encapsulation formats for VLAN identification.
1.1.3 VLAN Classification
Based on how VLANs are established, VLANs fall into different categories. The
following types are the most commonly used:
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Port-based
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MAC address-based
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Protocol-based
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IP-subnet-based
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Policy-based
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Other types
The S3610&S5510 series Ethernet switches support port-based VLAN, protocol-based
VLAN, and IP-subnet-based VLAN.
