DHCP Service

[learnsec]

hi,

i want to configure the "ip helper-address" command on an interface vlan on the main switch, this command to work requires the "service dhcp" command to be enabled globaly on the switch. do you think configuring the "service dhcp" command alone globaly on the switch will it affect anything (because i dont use the dhcp)? as long as i didnt configure any dhcp server ip address or dhcp pool?

regards,

[Kishore Chennupati]

Hello,

"Service DHCP" is used when you configure DHCP server on the switch/router. You do not need it for "IP helper-address" configuration. "IP helper-address" is used in different contexts to convert regular broadcast traffic to directed

unicast.

HTH

Regards

Kishore

[cadet alain · Accepted solution]

Hi Kishore,

You need the service dhcp enabled to do dhcp relay. Just try it with the service dhcp disabled and you'll see it won't work.

To the OP: no it won't have any effect except permitting you to function as a dhcp relay agent.

Regards.

Alain

[Kishore Chennupati]

Hi Alain,

Thanks for your input. However,I beg to differ here. I have configured heaps of switches and routers without the service dhcp and have configured "ip helper address" where by the switch acts as a relay agent and they work without any issues in production environment.

Of course I haven't tried to do a "no service dhcp"

If you want I can send in a config that is runnig live in our network for your kind review. What I am saying here is that you dont explicitly have to configure the service dhcp to run a switch or a router as a relay agent

HTH

Regards

Kishore

[cadet alain · Accepted solution]

Hi Kishore,

of course the default is service dhcp enabled so you don't have to explicitly activate it  by default but if it was disabled then you would have to enable it back for the dhcp relay agent function to work.

Regards.

Alain

[Kishore Chennupati]

you are right. I neva had to configure one for the box to act as a relay agent. Its on by default. Thanks for correcting me.

BTW, the CCNP logo is nice and shiny

[learnsec]

Thank you kishore and cadet for your clarification.

regards,