一、級聯簡介
級聯是交換機組網的一種結構，級聯技術可以實現兩臺或兩臺以上交換機之間的互聯，在多種網絡中被廣泛應用二、簡單實驗
實驗拓撲：
1-1，1-2，1-3三臺交換機級聯至1-3；2-1，2-2兩臺級聯至2-2；1-3和2-2上聯至HX，所有網段網關都在HX上。
Server1A：10.3.1.1/24 10.3.1.254 vlan 10
Server1B：10.3.1.2/24 10.3.1.254 vlan10
Server2A：10.3.2.1/24 10.3.2.254 vlan 20
Server2B：10.3.2.2/24 10.3.2.254 vlan 20
Server3A：10.3.3.1/24 10.3.3.254 vlan 30
Server3B：10.3.3.2/24 10.3.3.254 vlan 30
開始配置：
交換機1-1配置：1口級聯1-2，2口vlan30
vlan batch 10 20 30
#
interface GigabitEthernet0/0/1
port link-type trunk
port trunk allow-pass vlan 2 to 4094
#
interface GigabitEthernet0/0/2
port link-type access
port default vlan 30
交換機1-2配置：4口級聯1-1，2口級聯1-3，1口vlan10，3口vlan20
vlan batch 10 20 30
#
interface GigabitEthernet0/0/1
port link-type access
port default vlan 10
#
interface GigabitEthernet0/0/2
port link-type trunk
port trunk allow-pass vlan 2 to 4094
#
interface GigabitEthernet0/0/3
port link-type access
port default vlan 20
#
interface GigabitEthernet0/0/4
port link-type trunk
port trunk allow-pass vlan 2 to 4094
交換機1-3配置：2口級聯1-2，3口上聯HX，1口vlan20
vlan batch 10 20 30
#
interface GigabitEthernet0/0/1
port link-type access
port default vlan 20
#
interface GigabitEthernet0/0/2
port link-type trunk
port trunk allow-pass vlan 2 to 4094
#
interface GigabitEthernet0/0/3
port link-type trunk
port trunk allow-pass vlan 2 to 4094
交換機2-2配置：1口上聯HX，2口級聯2-1
vlan batch 10 20 30
#
interface GigabitEthernet0/0/1
port link-type trunk
port trunk allow-pass vlan 2 to 4094
#
interface GigabitEthernet0/0/2
port link-type trunk
port trunk allow-pass vlan 2 to 4094
交換機2-1配置：1口級聯2-2，2口vlan10
vlan batch 10 20 30
#
interface GigabitEthernet0/0/1
port link-type trunk
port trunk allow-pass vlan 2 to 4094
#
interface GigabitEthernet0/0/2
port link-type access
port default vlan 10
HX配置：2口Trunk至1-3，3口Trunk至2-2，3類server的網關配置，1口vlan30
vlan batch 10 20 30
#
interface Vlanif1
#
interface Vlanif10
ip address 10.3.1.254 255.255.255.0
#
interface Vlanif20
ip address 10.3.2.254 255.255.255.0
#
interface Vlanif30
ip address 10.3.3.254 255.255.255.0
#
interface MEth0/0/1
#
interface GigabitEthernet0/0/1
port link-type access
port default vlan 30
#
interface GigabitEthernet0/0/2
port link-type trunk
port trunk allow-pass vlan 2 to 4094三、小結
1、trunk鏈路允許所有vlan通過，但級聯的交換機需起相應vlan
2、vlan間通信依靠HX（三層交換）的直連路由