ip dhcp smart-relay

ip dhcp smart-relay

2010-04-01 11:20

Setting the Gateway Address of the DHCP Broadcast to a Secondary Address Using Smart Relay Agent Forwarding Perform this task to configure smart relay agent forwarding. You only need to configure helper addresses on the interface where the UDP broadcasts that you want to forward to the DHCP server are being received, and you only need the ip dhcp smart-relay command configured if you have secondary addresses on that interface and you want the router to step through each IP network when forwarding DHCP requests. Without the smart relay agent configured, all requests are forwarded using the primary IP address on the interface. If the ip dhcp smart-relay command is configured, the relay agent counts the number of times the client retries sending a request to the DHCP server when there is no DHCPOFFER message from the DHCP server. After three retries, the relay agent sets the gateway address to the secondary address. If the DHCP server still does not respond after three more retries, then the next secondary address is used as the gateway address. 我的理解：接口下有两个地址情况下，如果使用了ip dhcp smart-relay,首先使用primary的地址，如果连续三次发送DHCP request都没有收到DHCP offer的回应，就使用secondary. 假设没有ip dhcp smart-relay，那就一直用primary地址，而不会用secondary地址转发UDP广播包。 如果所有接口下只有一个地址，ip dhcp smart-relay没有意义。 This functionality is useful when the DHCP server cannot be configured to use secondary pools. SUMMARY STEPS 1. enable 2. configure terminal 3. ip dhcp smart-relay