H3C S3600 Series Operation Manual page 48

Operation Manual – DHCP
H3C S3600 Series Ethernet Switches-Release 1510
Operation
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 handshake function is enabled, the DHCP relay sends
the handshake packet (the DHCP-REQUEST packet) which carries includes the IP
address recorded in the binding and its own bridge MAC address to the DHCP server
periodically.
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 handshake 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
address-check enable
Operation
system-view
DHCP relay
dhcp relay hand enable
DHCP relay
dhcp relay hand disable
Chapter 3 DHCP Relay Configuration
Command
Required
By
checking function is disabled.
(Only
switches among S3600 series
switches
configuration.)
Command
3-7
Description
default, the address
S3600-EI series
support
Description
—
By default, the DHCP relay
handshake function
enabled.
(Only S3600-EI series
switches among S3600
series switches support
this configuration.)
this
is