拓扑图
接口地址池
PC5通过接口地址池获取地址，DHCP服务器和VLAN40的网关为SW4 10.0.40.254
SW4
#
sysname Huawei
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vlan batch 10 20 30 40
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dhcp enable
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interface Vlanif40ip address 10.0.40.254 255.255.255.128dhcp select interface
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interface GigabitEthernet0/0/2port link-type trunkport trunk allow-pass vlan 10 20 40
#
SW3
#
sysname SW3
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undo info-center enable
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vlan batch 10 20 30 40
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dhcp enable
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interface Ethernet0/0/1port link-type trunkport trunk allow-pass vlan 10 20 40#
interface Ethernet0/0/4port link-type accessport default vlan 40抓包
全局地址池&&DHCP中继
PC4和PC6通过全局地址池获取地址，
SW4
#
interface Vlanif10ip address 10.0.10.254 255.255.255.0dhcp select relaydhcp relay server-ip 10.0.30.2
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interface Vlanif20ip address 10.0.20.254 255.255.255.0dhcp select relaydhcp relay server-ip 10.0.30.2
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interface Vlanif30ip address 10.0.30.4 255.255.255.0
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interface GigabitEthernet0/0/1port link-type accessport default vlan 30SW3
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interface Ethernet0/0/2port link-type accessport default vlan 10
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interface Ethernet0/0/3port link-type accessport default vlan 20R1
跨网段一定要配置静态路由 ，服务器的回复包才能达到客户端
客户端跨网段通信是由中继实现的
#
interface GigabitEthernet0/0/0ip address 10.0.30.2 255.255.255.0 dhcp select global
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ip route-static 10.0.10.0 255.255.255.0 10.0.30.4
ip route-static 10.0.20.0 255.255.255.0 10.0.30.4抓包
验证
基于接口地址池获取的地址 ，客户端地址是网关同网段的IP地址
基于全局地址池获取的地址，
DHCP服务器会选择与接收DHCP请求报文的接口IPv4地址处于同一网段的地址池来进行分配。
问题
SW4的vlanif30的IP地址配置错误导致，和R1无法通信，中继的数据报发不过去，获取不到地址
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