In a large network, when adding and removing network hosts to the network or reconfiguring network parameters, the manual configuration method is too laborious and prone to IP conflicts. At this time, the DHCP service is very useful. When an administrator wants to change the system's IP address in a large amount, or when reconfiguring all systems, the administrator only needs to edit a DHCP configuration file on the server. If the DNS or gateway in the network changes, you can also use DHCP to modify the settings. Instead of setting it up for each client. You can reduce the workload of the administrator. These modifications will take effect as soon as the customer reboots the system or the network is restarted. Having said that, I am going to say the topic now. Everyone knows that in a network segment, if there are two DHCP servers, there may be problems, such as IP address conflicts. So generally it is a DHCP server. But once this server has problems, it hangs. That still does not kill the network management? In a large network, in order to provide stable services, redundancy is necessary. Can the DHCP service also do backups? The answer is yes. But the backup here is a bit special. The DHCP servers themselves cannot be backed up each other. The IP address ranges they occupy cannot overlap, and the IP addresses conflict. Therefore, the backup we do here is to split the IP address range into two servers. This avoids the conflict when DHCP assigns an IP address. As an example, in the subnet of the network 10.0.0.0/24, there are two DHCP servers, namely DHCP1:10.0.0.1 and DHCP2:10.0.0.2.
disposed on DHCP1 fragment is:
subnet 10.0.0.0 netmask 255.255.255.0 {
range 10.0.0.3 10.0.0.100;
} cultivated on DHCP2 fragment is: < BR> subnet 10.0.0.0 netmask 255.255.255.0 {
range 10.0.0.101 10.0.0.254;
}
we can see two DHCP servers to work in a network, the IP assignment together Addresses do not conflict because their IP address ranges are not duplicated.
Well, the above said is only a segment on a network. What if there are multiple network segments in a network? The same can be done. Here
another example, there are two sub-networks and 10.0.0.0/24 20.0.0.0/24. Two DHCP servers, DHCP1 and DHCP2. Create two scopes on DHCP1. The following is the configuration fragment:
subnet 10.0.0.0 netmask 255.255.255.0 {
range 10.0.0.1 10.0.0.100;
} subnet 20.0.0.0 netmask 255.255.255.0 {
range 20.0.0.100 20.0.0.200;
} Two scopes are also built on DHCP2. The following is the configuration fragment:
subnet 20.0.0.0 netmask 255.255.255.0 {
range 20.0.0.1 20.0 .0.100;
} subnet 10.0.0.0 netmask 255.255.255.0 {
range 10.0.0.100 10.0.0.200;
} I don't know if I can see it clearly, DHCP1 is the main server of 10.0.0.0.0/24 (temporary How to say), is also a backup server of 20.0.0.0/24. DHCP2 is the primary server of 20.0.0.0/24 and also the backup server of 10.0.0.0/124. In this way, they back up each other, which improves the stability of the network. The above is one and two sub-networks. What if there are multiple sub-networks? In general, there are 2 or 3 DHCP servers in a network. Other subnets can be set up with relay agents to provide them with DHCP services. The first time I wrote original, but the technology is not home, I can only write the experiment process, it is original.