1. From the router's point of view, a router without dhcp is similar to a switch. It cannot automatically assign IP addresses to connected terminals and needs to be set manually or used as a switch.

This is how the second route is established. The second route turns off the DHCP service and allows the first route to assign ip to avoid IP conflicts.

2. Whether the computer turns on DHCP is related to whether you can automatically obtain the IP address. If you don't open the IP address, you can set it manually.

DHCP (Dynamic Host Configuration Protocol) is a local area network protocol, which works with UDP protocol. It has two main purposes: automatically assigning IP addresses to internal networks or network service providers, and providing users or internal network administrators with the means to centrally manage all computers. It is described in detail in RFC 2 13 1.

DHCP has three ports, of which UDP67 and UDP68 are normal DHCP service ports, serving as DHCP server and DHCP client respectively. Port 546 is used for DHCPv6 clients, but not for DHCPv4. It is used for DHCP failover, which is a service that needs to be started specially. DHCP failover is used for "hot standby".

DHCP client

On the network equipment supporting DHCP function, the designated port is used as the DHCP client, and the information such as IP address is dynamically obtained from the DHCP server through DHCP protocol, so as to realize centralized management of the equipment. Generally applied to the network management interface of network equipment.

DHCP clients can bring the following benefits:

And that time for configure and deploying equipment is reduce.

And the possibility of configuration errors is reduced.

IP address assignment of devices can be managed centrally.

dhcp server

DHCP server refers to a series of IP addresses controlled by the server, and the client can automatically obtain the IP address and subnet mask assigned by the server when logging in to the server.

DHCP relay agent

DHCPRelay(DHCPR)DHCP relay is also called DHCP relay agent. DHCP relay agent forwards DHCP packets between DHCP server and client.

When the DHCP client and server are not on the same subnet, there must be a DHCP relay agent to forward DHCP requests and reply messages. The data forwarding of DHCP relay agent is different from the usual routing forwarding, which is relatively transparent, and devices generally do not modify the IP packet content.

After receiving the DHCP message, the DHCP relay agent regenerates the DHCP message and forwards it. In the view of DHCP client, DHCP relay agent is like DHCP server; In the view of DHCP server, DHCP relay agent is like DHCP client.

References:

Baidu Encyclopedia Entry-"DHCP"