Tổng quan về VLAN (VLAN Overview)
•
Segmentation
•
Flexibility
•
Security
3rd floor
2nd floor
1st floor
SALES HR ENG
A VLAN = A broadcast domain = Logical network (subnet)

Tổng quan về VLAN (VLAN Overview)

Nội Dung

Khái niệm về VLAN

Khái niệm về Trunking

VLAN Trunking Protocol (VTP)

Cấu hình switch for trunking

Thay đổi kết nối VLAN

Thay đổi spanning-tree

Tổng quan về VLAN (VLAN Overview)

Green
VLAN
Black
VLAN
Red
VLAN
•
Each logical VLAN is like a separate physical bridge
•
VLANs can span across multiple switches
Hoạt Động của VLAN (VLAN Operations)

Switch A
Green
VLAN
Black
VLAN
Red
VLAN
Switch B
Green
VLAN
Black
VLAN
Red
VLAN

Trunk
•
Each logical VLAN is like a separate physical bridge

(Application specific integrated
circuits)

Not intrusive to client stations,
client does not see the ISL
header

Effective between switches,
routers and switches, switches
and servers with ISL network
interface cards
ISL trunks enable VLANs across a backbone
VLAN Tag
added by
incoming port
VLAN Tag
stripped by
forwarding port
Inter-Switch
Link carries
VLAN identifier

ISL Tagging

ISL Encapsulation
ISL Header
ISL Header
26 bytes
26 bytes
Encapsulated Ethernet frame

Server
C
l
i
e
n
t
Transparent
•
Sends/forwards
advertisements
•
Synchronize
•
Not saved in
NVRAM
•
Create vlans
•
Modify vlans
•
Delete vlans
•
Sends/forwards
•
advertisements
•
Synchronize
•
Saved in NVRAM

VTP Pruning

Tăng băng thông bằng cách giảm và cắt bỏ
những tải không cần thiết

Example: Station A gửi broadcast, broadcast
chỉ được chuyển đến các port được gán cho red
VLAN

VTP Pruning
Switch 4
Switch 2
Switch 6 Switch 3 Switch 1
Port 2
Flooded
traffic is
pruned
Red
VLAN
Port 1
Switch 5
A
B

Cấu Hình VLAN
Cấu Hình Vlan trên Catalyst
1900 và 2950

Rcs-Sud-Est
•