IP-COM G3210P, Руководство пользователя

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Advanced Settings
dispersed as they are logically related instead of physically on the same VLAN. Thus
network administrators do not need to re-configure the network when a VLAN
member changes its location.
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Better network security. PCs in different VLANs cannot intercommunicate directly.
Inter-VLAN communication can only be achieved using a router or other layer 3
devices that are able to perform Layer 3 forwarding, which can ensure better security
for different departments in enterprise networking.
This device supports 802.1Q VLAN, Port VLAN and voice VLAN. Next we will give
explanations one by one.
1 802.1Q VLAN
Officially issued by IEEE in 1999, 802.1Q is used for regulating international VLAN
standard and makes VLAN intercommunication among different vendors
’ devices possible.
As defined in IEEE 802.1Q, a four-byte VLAN tag is inserted after the source MAC field to
identify frames of different VLANs.
Explanations for 802.1Q tag are described below:
Field Description
TPID
A 16-bit field set to a value of 0x8100 in order to identify the frame as
an IEEE 802.1Q-tagged frame.
Priority
A 3-bit field with a valid range of 0~7 to identify packet frame priority.
When blocking occurs, packets with higher priority will be sent out
preferentially.
CFI
A 1-bit field for identifying whether the MAC address is encapsulated in
the standard format.
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. For Ethernet switches, it is set