DHCP Backup.

[maziyar daemi]

I have two routers 1921 and 2901 and both of them are connecting to one Reliable Internet Line from one ISP. 1921 master router and 2901 as a Slave. this is my question, how i can make a Backup DHCP Sever in 2901 as a same IP address generation?

Example :

1921-------> Ip Generator 10.1.1.0 /24

2901-------> Ip Generate 10.1.1.0 /24

both generate same ip address, when the Master is lost, Slave could be Covered the LAN.

Your help could be appriciated.

[terrencepayet · Accepted solution]

Hi Maziyar,

You can use HSRP between your routers. 1 router will be the active router and the other backup. You will be able to apply the DHCP config on both routers without any loop issues.

exmaple config below:

Config for 1921

Go under you LAN interface:

standby 1 ip 10.1.1.1 (GW)

standby 1 preempt

standby 1 priority 150 (making it the active router)

Config for 2901

Go under you LAN interface:

standby 1 ip 10.1.1.1 (GW)

standby 1 preempt

you can use timers to adjust the amount of time your backup will wait in order to become active.

HTH.

Regards,

terence

[smehrnia · Accepted solution]

Hey Maziyar,

I dont think it is possible to have a master/slave scenario for DHCP servers. the best practice is to split ur IP Pool between two dhcp servers. have that in mind; client - dhcp communication starts with bootp broadcasts. dhcp lease database is stored locally so in case of a failure there will be problems in ur network!

HTH,

plz Rate if it helped,

Soroush.

[maziyar daemi]

There are two seperated Solutions, Actually I would like, HSRP to carry DHCP pool when the master Got Fault in any reason.

[SOcchiogrosso]

The local DHCP binding database is only stored locally, best way would be to configure the scope on both routers and exlcude half the scope on router1 and then exclude the other half of the scope on router2.

DHCP is broadcast based, whether or not the router is HSRP Active/Standby it will still reply to the broadacst, which cause issues. Just make sure the split scope is capable of sustaining the entire network.

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