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This article mainly introduces the work flow of DHCP, which is very detailed and has certain reference value. Friends who are interested must finish it!

The workflow of DHCP has four steps, which are

DHCP discover: the new host sends a broadcast packet, saying that it needs to assign an IP

DHCP offer:dhcp server receives the request and sends a broadcast packet telling the new host the assigned ip and other information.

DHCP request: the new host receives a message from dhcp server and knows that it has a new ip. Send a broadcast packet and tell dhcp server that you know the newly allocated ip.

DHCP ack: broadcast a message packet telling other hosts on this network that new friends have joined.

DHCP DISCOVE

When a new host (MAC address is 00:0b:82:01:fc:42) has just joined a network, it does not have an IP address, so it needs to send a broadcast packet for the network administrator DHCP SERVER to receive the packet (dhcp server is specifically used to allocate ip and manage ip). The format of the broadcast package is as follows

Here is an additional point of knowledge: 255.255.255.255 is a special ip address for broadcasting purposes. However, the scope of its broadcast is limited, and the transmission will stop when it reaches the gateway.

DHCP OFFER

When dhcp server receives Boot Request, it knows that a new host needs to assign IP. At this time, dhcp server also sends a broadcast packet (because the new host has not yet been assigned to IP). The information in it is the IP, subnet mask, lease period and other information assigned to the new host.

DHCP REQUEST

The new host received a message from dhcp server that it knew the IP to which it was assigned, but at this time, it could not be used yet. I had to tell dhcp server that I had received the ip address. Therefore, you still need to send a broadcast packet to tell dhcp server.

DHCP ACK

When dhcp server receives the boot request message, it broadcasts and returns a DHCP ACK message packet to the client, indicating that it has accepted the client's choice, and puts the legal rental information and other configuration information of this IP address into the broadcast package and sends it to the client to welcome it into the network family.

At this point, the new host has its own IP address, and then the packet will be sent with its own IP.

The above is all the contents of this article "the Workflow of DHCP". Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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