Juniper-EX交换机DHCP获取异常。

在实际使用中可能会遇到切换VLAN、办公桌搬迁、PC在会议室使用后，无法获取到IP地址的情况。
故障表现为：
DHCP服务器：新的VLAN的网关，
IP地址：旧的VLAN地址，
使用命令重新获取，重启交换机都无法解决该问题。

Juniper jtac回复，需要添加一个配置，且需要清楚DHCP服务器绑定，原因是交换机存在Bug。
保险起见，配置修改前需要先将设备升级至junos-18以上的版本，18.2R3.0亲测有效。

set system services dhcp-local-server requested-ip-interface-match
clear dhcp server binding （具体ip/all）
show dhcp server binding 可查看绑定情况

以下是Juniper的恢复内容：
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Dear Customer,
Configuring the following command will address this problem. The command will keep the device from providing an IP address from an incorrect pool just because the end-user device is requesting it.
set system services dhcp-local-server requested-ip-interface-match
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因为客户端说我自己要那个错误的地址，交换机就给他了，这条命令要静止这种情况发生？
这条命令可以阻止客户端获取错误的地址。
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