DHCP (Dynamic Host Configuration Protocol)

What is DHCP?

It is used to provid ip address to client automatically. It is also provide subnet, default gateway, dns server ip address also.

It is used port number 67 for server and 68 for client.

DHCP operations fall into four phases: server discovery, IP lease offer, IP lease request, and IP lease acknowledgement

DORA Discovery Offer Request Acknoledge

DISCOVER

source ip address : 0.0.0.0

source mac : A

destination ip address : 255.255.255.255.(Broadcast address)

Destination Mac: FFFF:FFFF:FFFF:FFFF(bROADCAST MAC)

Offer

Source ip address : 192.168.1.1

source mac : B

destination ip address : 255.255.255.255.(Broadcast address)

Destination Mac: A

Request

Source ip address : 10.1.1.1

source mac : A

destination ip address : 255.255.255.255

Destination Mac: FFFF:FFFF:FFFF:FFFF

Aknowledgement

Source ip address : 192.168.1.1

source mac : B

destination ip address : 10.1.1.1

Destination Mac: A

!Untitled

Lets configure :

Int gig0/0/0

ip add 192.168.1.1 255.255.255.0

no sh

ip dhcp pool KP

network 192.168.1.0 255.255.255.0

default-roouter 192.168.1.1

dns-server 192.168.1.254

show ip dhcp binding (To show all the IP address)

ip dhcp excluded-address 192.168.1.5 192.168.1.10