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DHCP (Dynamic Host Configuration Protocol) . Cisco, , ( ) DHCP.

Merion Academy


DHCP , , , , DHCP. - .


1. IP

IPv4 , . , IP- . , DHCP , IP-. , , .

show ip dhcp conflict , DHCP. ping . ARP. , , .

:

Router# show ip dhcp conflict
IP address Detection Method Detection time
192.168.1.33 Ping Feb 19 2018 10:33 AM
192.168.1.48 Gratuitous ARP Feb 19 2018 11:29 AM 

IP address , Detection Method (Ping , Gratuitous ARP ARP ) Detection time .

show ip dhcp binding.


2.

, , , . show interface [] , UP, , DHCP.


3. , IP

DHCP IP . , DHCP.


4:

DHCP IP , , DHCP .

DHCP , . , , STP RSTP. PortFast DHCP, .


5: DHCP VLAN

, DHCP, VLAN, DHCP-. DHCP , , DHCP (relay agent). , DHCP.


DHCP

DHCP , , , DHCP helper .

, ip helper-address . , DHCP , DHCP. show ip interface [] . , no service dhcp . DHCP . show running-config | include no service dhcp. , .


DHCP

, DHCP-, DHCP . , . ACL (Access Control List).

Access List, UDP 67 68. , DHCP. ACL debug ip packet DHCP.

Router(config)# access-list 100 permit udp any any eq 67
Router(config)# access-list 100 permit udp any any eq 68
Router(config)# end
Router# debug ip packet 100
IP packet debugging is on for access list 100
*IP: s-0.0.0.0 (GigabitEthernet1/1), d-255.255.255.255, len 333, rcvd 2
*IP: s-0.0.0.0 (GigabitEthernet1/1), d-255.255.255.255, len 333, stop process pak for forus packet
*IP: s-192.168.1.1(local), d-255.255.255.255 (GigabitEthernet1/1), len 328, sending broad/multicast

, DHCP . IP- 0.0.0.0, , - 255.255.255.255, DHCP . , DHCP. , , IP- UDP, DHCP.

DHCP debug ip dhcp server. , .

Router(config)#debug ip dhcp server events
DHCPD: returned 192.168.1.11 to address pool POOL-1
DHCPD: assigned IP address 192.168.1.12 to client 0011:ab12:cd34
DHCPD: checking for expired leases
DHCPD: the lease for address 192.168.1.9 has expired
DHCPD: returned 192.168.1.9 to address pool POOL-1

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