網路原理() RSE6 Section 6.1

VLAN
虛擬區域是一種建構於區域網路交換技術的網路管理的技術，網管人員可以藉此透過控制交換器有效分派出入區域網的封包到正確的出入埠，達到對不同實體區域網中的裝置進行邏輯分群管理，並降低區域網內大量資料流通時，因無用封包過多導致壅塞的問題，以及提昇區域網的資訊安全保障。

Logical broadcast domain
A VLAN creates a logical broadcast domain that can span multiple physical LAN segments. VLANs improve network performance by separating large broadcast domains into smaller ones.

data vlan
A data VLAN is a VLAN that is configured to carry user-generated traffic. A VLAN carrying voice or management traffic would not be a data VLAN.

default vlan
All switch ports become a part of the default VLAN after the initial boot up of a switch loading the default configuration. Switch ports that participate in the default VLAN are part of the same broadcast domain. 

native vlan
A native VLAN is assigned to an 802.1Q trunk port. Trunk ports are the links between switches that support the transmission of traffic associated with more than one VLAN. 

management vlan
A management VLAN is any VLAN configured to access the management capabilities of a switch. VLAN 1 is the management VLAN by default.

show vlan brief

voice vlan
A separate VLAN is needed to support Voice over IP (VoIP).

vlan trunk
A trunk is a point-to-point link between two network devices that carries more than one VLAN.

vlan segmentation
Within a switched network, VLANs provide segmentation and organizational flexibility.

IEEE 802.1Q
IEEE 802.1Q以及VLAN Tagging屬於網際網路下IEEE 802.1的標準規範，允許多個網橋在資訊不被外洩的情況下公開的共用同一個實體網路。IEEE 802.1Q -英文縮寫寫為dot1q，經常在實現乙太網路封裝協議的架構下被提及。

vlan tagging
when Ethernet frames are placed on a trunk, information about the VLANs to which they belong must be added. This process, called tagging, is accomplished by using the IEEE 802.1Q header, specified in the IEEE 802.1Q standard.

canonical format identifier (CFI)
A 1-bit identifier that enables Token Ring frames to be carried across Ethernet links.

user priority
用戶優先權,A 3-bit value that supports level or service implementation.

vlan id
A 12-bit VLAN identification number that supports up to 4096 VLAN IDs.

type
A 2-byte value called the tag protocol ID (TPID) value. For Ethernet, it is set to hexadecimal 0x8100.

show interfaces int switchport