dual ip-helper addresses but only one authorized DHCP server

[Angelo ANELLO]

We are trying to create some redundancy in our network to minimise the amount of downtime our system will have if our primary DHCP server goes down.

At the moment we are only using one DHCP server in production.  We have a secondary DHCP server in waiting.  It is not authorised to distribute DHCP addresses and will only be authorised in the event of our primary DHCP server failing.  We have copied our DHCP database to the secondary server so addressing shouldnt be a problem.

What i would like to know is if i configure two ip-helper addresses on each of our routers to point to the first and secondary DHCP servers, will there be an increase in network traffic due to the second server not responding to requests as it will be inactive until the primary server goes down?

We want to have the secondary address in the event of DHCP server failure and do not want to be scrambling around trying to reconfigure our routers to accept the new address that points to the second server.

Our major conern is the amount of network traffic incurred as a result of the second server not responding to requests due to being offline.

Any feedback is welcomed and appreciated

Regards

[Thotsaphon Lueangwattanaphong · Accepted solution]

Hi,

   Yes, It's going to increase network traffic for sure but it would not be a big problem because you will face this when clients try to receive IP addresses via DHCP. It's a good idea to do that. You have to make sure that the secondary DHCP server is down or has different scopes if they both are up. Router forwards dhcp requests to both dhcp servers that is what it does.

HTH,

Toshi

[cadet alain · Accepted solution]

Hi,

We want to have the secondary address in the event of DHCP server  failure and do not want to be scrambling around trying to reconfigure  our routers to accept the new address that points to the second server.

You could also configure an ip helper-address pointing to a broadcast address provided ip directed-broadcast is not disabled on the interface towards the servers.

Regards.

Alain