D-Link DES-3326 User Manual - page 78
DES-3326 Layer 3 Fast Ethernet Switch User’s Guide
64
Switch Management and Operating Concepts
configuration, ensures that address conflicts do not occur, and
helps to conserve the use of IP addresses through the centralized
management of address allocation.
Note: For multiple DHCP servers on different subnets to
communicate, the BOOTP Relay function on the DES-
3326 must be used to provide a path for the servers to
communicate. Servers are identified by IP address.
Dynamic address allocation enables a client to be assigned an IP
address from a pool of free addresses. Each address is assigned
with a lease and a lease expiration period. The client must renew
the lease to continue using the assigned address. Dynamically
assigned addresses can be returned to the free address pool if the
computer is not being used, if it is moved to another subnet, of if its
lease expires. Usually, network policy ensures that the same IP
address is assigned to a client each time and that addresses
returned to the free address pool are reassigned.
When the address lease expires, the DHCP client enters the
renewing state. The client sends a request message to the DHCP
server that provided the address. The DHCP server sends an
acknowledgement that contains the new lease and configuration
parameters. The client then updates its configuration values and
returns to the bound state.
When the DHCP client is in the renewing state, it must release its
address immediately in the rare event that the DHCP server sends
a negative acknowledgment. The DHCP server sends this message
to inform a client that it has incorrect configuration information,
forcing it to release its current address and acquire new
information.
If the DHCP client cannot successfully renew its lease, the client
enters a rebinding state. The client then sends a request message
to all DHCP servers in its range, attempting to renew its lease.
Any DHCP server that can extend the lease sends and
acknowledgement containing the extended lease and updated