Huawei Quidway S3900 Series Operation Manual page 626

Operation Manual - DHCP
Quidway S3900 Series Ethernet Switches-Release 1510
Operation
Enter interface view
Enable the address
checking function
II. Configuring DHCP relay handshake
When the DHCP client obtains an IP address from the DHCP server through the
DHCP relay, the DHCP relay records the binding relationship of the IP address and the
MAC address. After the DHCP relay function is enabled, the DHCP relay sends the
handshake packet (the DHCP-REQUEST packet) periodically to the DHCP server
according to the IP address and its MAC address, which are specified in the binding
relationship.
If the DHCP server returns the DHCP-ACK packet, it indicates that the IP address
can be assigned. The DHCP relay ages the corresponding entry in the user
address table.
If the DHCP server returns the DHCP-NAK packet, it indicates that the lease of
the IP address is not expired. The DHCP relay does not age the corresponding
entry.
After the DHCP relay function is disabled, the DHCP relay does not send the
handshake packet (the DHCP-REQUEST packet) periodically to the DHCP server.
When the DHCP client releases this IP address, the client unicasts the
DHCP-RELEASE packet to the DHCP server.
The DHCP relay does not process this packet, so the user address entries of the
DHCP relay cannot be updated in real time.
Table 3-5 Enable/disable DHCP relay handshake
Enter system view
Enable
handshake
Disable
handshake
interface interface-type
interface-number
address-check enable
Operation
system-view
DHCP relay dhcp
enable
DHCP relay
dhcp
disable
Huawei Technologies Proprietary
Chapter 3 DHCP Relay Configuration
Command
—
Required
By
checking function is disabled
Command
relay hand
relay hand
3-7
Description
default, the address
Description
—
By default, the DHCP relay
function is enabled
Only S3900-EI series
switches among S3900
series switches support
this configuration