What are the reasons for the restrictions of Vlan 4096?
What is the reason for the limitation of Vlan 4096? many beginners are not very clear about it. In order to help you solve this problem, the following editor will explain it in detail. People with this need can come and learn. I hope you can get something.
The maximum possible value for a VLAN configuration is 4094, and its origin is as follows:
IEEE802.1q protocol is also known as "Virtual Bridged Local Area Networks" (Virtual bridged Local area Network) protocol, which mainly defines the implementation method of VLAN.
The IEEE802.1q tag frame format is as follows:
| | Preamble (7bytes) | SFD (1bytes) | DA (6bytes) | SA (6bytes) | TPID (2bytes) | TCI (2bytes) | Type Length (2bytes) | Data (42~149bytes) | CRC (4bytes) |
Where TCI is the label control information field (2bytes), including user priority (User Priority), canonical format indicator (Canonical Format Indicator,CFI) and VLAN ID.
"User Priority" defines user priorities, including 8 (2 ^ 3) priorities, accounting for 3 digits
"CFI" occupies 1 place.
"VID" (VLAN ID) is a 12-bit identification field for VLAN. 4096 (2 ^ 12) VLAN recognition is supported. In 4096 of the possible VID, VID=0 is used to identify the frame priority. 4095 (FFF) is reserved, so the maximum possible value for VLAN configuration is 4094.
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