H3C Technologies H3C S5560 Series Switches - Manual (Page 183)

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Figure 63 Assignment involving four messages
Address/prefix lease renewal
An IPv6 address/prefix assigned by a DHCPv6 server has a valid lifetime. After the valid lifetime expires,
the DHCPv6 client cannot use the IPv6 address/prefix. To use the IPv6 address/prefix, the DHCPv6 client
must renew the lease time.
Figure 64 Using the Renew message for address/prefix lease renewal
As shown in Figure 64 , at T1, the DHCPv6 client sends a Renew message to the DHCPv6 server. The
recommended value of T1 is half the preferred lifetime. The DHCPv6 server responds with a Reply
message, informing the client whether the lease is renewed.
Figure 65 Using the Rebind message for address/prefix lease renewal
As shown in Figure 65 :
• If the DHCPv6 client does not receive a response from the DHCPv6 server after sending a Renew
message at T1, it multicasts a Rebind message to all DHCPv6 servers at T2. Typically, the value of
T2 is 0.8 times the preferred lifetime.
• The DHCPv6 server responds with a Reply message, informing the client whether the lease is
renewed.
• If the DHCPv6 client does not receive a response from any DHCPv6 server before the valid lifetime
expires, the client stops using the address/prefix.