What is DHCP and its Functions?

To create a network via TCP/IP, it is necessary to build each individual station to configure. For larger networks a lot of planning and work is required. To avoid this, you can use the Dynamic Host Configuration Protocol (DHCP) for automatic configuration of TCP/IP. But apart from this, DHCP is also capable of to manage and distribute IP addresses dynamically . Thus, a station is not necessarily a fixed IP address assigned.

For a TCP / IP network must have the following settings for each station are:

• Assignment of a unique IP address
• Assign a subnet mask (subnet mask)
• Assign the default gateway or default

Functioning of DHCP

DHCP follows a client-server architecture model. The DHCP server has a pool of IP addresses and these IP Addresses are allocated to it's clients. For larger networks, the DHCP server also know about the subnets and default gateway is there.If a station is started and there is a DHCP-enabled client, a reduced role in its mode of the TCP/IP stack driven. This does not have a valid IP address, no subnet mask and no default gateway. The only thing the client can make is IP broadcasts to send. The DHCP client sends a UDP packet with the destination address 255,255,255,255 and the source address 0.0.0.0. This serves as a broadcast address to request any available DHCP server. The UDP packet contains the hardware address (MAC address) of the station.

Each main DHCP server sends a UDP packet with the following data:

• MAC address of the client
• Possible IP address
• Duration of the IP address
• Subnet Mask
• IP address of the DHCP server / server-ID

From the selection of possibly more than one DHCP server looks for the DHCP-client an IP address out. Then it sends a positive message to the appropriate DHCP server. All other servers receive the message and just go by the adoption of the IP address for the benefit of another server. Subsequently, the assignment of IP address from the DHCP server to be confirmed. Once the DHCP client has the confirmation, it stores the data locally from. Finally, the TCP/IP stack fully launched.But not only the data to the TCP/IP network, DHCP can be awarded to the client.

Source : goarticles by andrew demm

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