Huawei Quidway S3900 Series Operation Manual page 589

Operation Manual - DHCP
Quidway S3900 Series Ethernet Switches-Release 1510
Note:
The static-bind ip-address command and the static-bind mac-address
command or the static-bind client-identifier command must be coupled.
In the same global DHCP address pool, if you configure the static-bind
client-identifier command after configuring the static-bind mac-address
command, the new configuration overwrites the previous one.
In the same global DHCP address pool, if the static-bind ip-address command,
the static-bind mac-address command, or the static-bind client-identifier is
executed repeatedly, the new configuration overwrites the previous one.
The IP address to be statically bound cannot be an interface IP address of the
DHCP server; otherwise static binding does not take effect.
A client can permanently use the statically-bound IP address that it has obtained.
The IP address is not limited by the lease time of the IP addresses in the address
pool.
Note:
To prevent malicious attacks to unused sockets and enhance security, S3900 series
Ethernet switches provide the following functions:
When DHCP is enabled, sockets UDP 67 and UDP 68 used by DHCP are enabled.
When DHCP is disabled, sockets UDP 67 and UDP 68 are disabled at the same
time.
The preceding functions are implemented as follows:
After you create a DHCP address pool by using the dhcp server ip-pool command,
sockets UDP 67 and UDP 68 will be enabled.
After you delete the DHCP address pool by using the undo dhcp server ip-pool
command and disable all the DHCP functions, sockets UDP 67 and UDP 68 will be
disabled.
II. Configuring to assign IP addresses dynamically
IP addresses dynamically assigned to DHCP clients (including those that are
permanently leased and those that are temporarily leased) belong to addresses
segments that are previously specified. Currently, an address pool can contain only
one address segment, whose ranges are determined by the subnet mask.
To avoid IP address conflicts, the IP addresses to be dynamically assigned to DHCP
clients are those that are not occupied by specific network devices (such as gateways
and FTP servers).
Huawei Technologies Proprietary
2-8
Chapter 2 DHCP Server Configuration