我对DHCP的理解是,客户端在网络上广播DHCP Discovery请求,网络上的任何设备都可以响应.因此,DHCP服务器需要IP地址,但为什么这个IP需要是静态的？ DHCP服务器可以在其他地方获取其地址,并且只要它具有IP,它仍然可以响应广播.
例如.
>服务器A,服务器B和客户端X都连接到同一台交换机
>服务器A是10.0.0.1,服务于10.0.0.X / 24
>服务器A配置为仅通过MAC过滤向服务器B提供IP
>服务器B从服务器A获取其IP,因此它位于10.0.0.X / 24
>服务器B服务10.0.1.X / 24
>客户端X连接并从服务器B获取IP
当然,一旦客户端X获得来自服务器B的IP,它将无法直接联系服务器B,因为它们位于不同的子网上.但这不是问题 – DHCP请求(最初)是广播,因此交换机上的每个人都会收到它.
忽略管理的观点,为什么我不能拥有
>具有静态IP的主DHCP服务器,它仅服务于其他DHCP服务器
>“辅助”DHCP服务器的地址范围
>从“辅助”DHCP服务器获取的客户端的地址范围
是否存在DHCP服务器必须具有静态IP的技术原因？
My understanding of DHCP is,a client broadcasts a DHCP Discovery
request on the network,and any device on the network can respond.
客户端也可以发出单播DHCP请求,更新请求以单播方式进行,因此客户端直接请求DHCP服务器.
如果DHCP更改了原始IP地址怎么办？续订将失败,下一个请求将以广播形式进行.这不是一种可以优化网络流量的行为.
微软：
Renewing a Lease The DHCP client first attempts to renew its lease
when 50 percent of the original lease time,known as T1,has passed.
At this point the DHCP client sends a unicast DHCPRequest message to
the DHCP server that originally granted its lease. If the server is
available,and the lease is still available,the server responds with
a unicast DHCPAck message and the lease is renewed.
ISC：
Internet Systems Consortium DHCP Client 4.2.2 Copyright 2004-2011 Internet Systems Consortium. All rights reserved. For info,please visit https://www.isc.org/software/dhcp/ Listening on LPF/eth0/00:0c:29:ac:18:75 Sending on LPF/eth0/00:0c:29:ac:18:75 Sending on Socket/fallback DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7 << First request DHCPREQUEST on eth0 to 255.255.255.255 port 67 DHCPOFFER from 10.0.0.253 DHCPACK from 10.0.0.253 bound to 10.0.0.6 -- renewal in 133 seconds. DHCPREQUEST on eth0 to 10.0.0.253 port 67 << Renewal DHCPACK from 10.0.0.253 bound to 10.0.0.6 -- renewal in 119 seconds. DHCPREQUEST on eth0 to 10.0.0.253 port 67 DHCPACK from 10.0.0.253 bound to 10.0.0.6 -- renewal in 118 seconds.
Once the lease has been granted,however,future DHCP
DHCPREQUEST/RENEWAL messages are unicast directly to the DHCP
Server
