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Command
Global Mode
ip dhcp conflict logging
no ip dhcp conflict logging
Admin Mode
clear ip dhcp conflict <address | all >
31.3 DHCP Relay Configuration
When the DHCP client and server are in different segments, DHCP relay is required to transfer
DHCP packets. Adding a DHCP relay makes it unnecessary to configure a DHCP server for
each segment, one DHCP server can provide the network configuration parameter for clients
from multiple segments, which is not only cost-effective but also management-effective.
DHCPDi scover ( Br oadcast )
DHCPO FFER( Uni cast )
DHCPREQ UEST( Br oadcast )
DHCPACK( Uni cast )
DHCP Cl i ent
As shown in the above figure, the DHCP client and the DHCP server are in different networks,
the DHCP client performs the four DHCP steps as usual yet DHCP relay is added to the
process.
1.
The client broadcasts a DHCPDISCOVER packet, and DHCP relay inserts its own IP
address to the relay agent field in the DHCPDISCOVER packet on receiving the
packet, and forwards the packet to the specified DHCP server (for DHCP frame format,
please refer to RFC2131).
2.
On the receiving the DHCPDISCOVER packets forwarded by DHCP relay, the DHCP
server sends the DHCPOFFER packet via DHCP relay to the DHCP client.
3.
DHCP client chooses a DHCP server and broadcasts a DHCPREQUEST packet,
DHCP relay forwards the packet to the DHCP server after processing.
4.
On receiving DHCPREQUEST, the DHCP server responds with a DHCPACK packet
Explanation
Enable/disable logging for DHCP address to
detect address conflicts.
Delete a single address conflict record or all
conflict records.
DHCP Rel ay
Figure 31-2: DHCP relay
31-36
DHCPDi scover
DHCPO FFER
DHCPREQ UEST
DHCPACK
DHCP Ser ver
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