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SERVICE DHCP required for external DHCP Server required?

Hi community,

I have a strange issue in one sub. There is a 3560 Switch which handels 2 VLANs, one for VoIP and one for Data.

There is a Windows DHCP Server running in the Data VLAN and in case the command "service dhcp" is not set,

the DHCP Server does not assign addresses to the VoIP VLAN. The IP Helper address is in place in the VoIP VLAN.

Who knows why the service dhcp is required in case that the switch does not run as DHCP Server?

Any ideas?

Thanks!

  • LAN Switching and Routing
Everyone's tags (1)
1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Bronze

Re: SERVICE DHCP required for external DHCP Server required?

service dhcp should not be needed to implement DHCP relay function with ip helper address

I'm sorry but that's not correct. You need service dhcp for DHCP Relay services.

Per documentation:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12.2_52_se/configuration/guide/swdhcp82.html#wp1218221

Regards

Edison

______

Each time you rate a CSC   discussion   we'll donate $1 to the American Red Cross Haiti fund up to a   maximum   donation of $10,000 USD.

https://supportforums.cisco.com/docs/DOC-8895

5 REPLIES
Hall of Fame Super Silver

Re: SERVICE DHCP required for external DHCP Server required?

Hello Andreas,

service dhcp should not be needed to implement DHCP relay function with ip helper address

http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12.2_52_se/configuration/guide/swdhcp82.html#wp1096758

you have probably found a workaround for an issue in your device.

knowing what IOS image is running on device would be of help in searching on bug toolkit

Also there are any features like DHCP snooping enabled on device?

Hope to help

Giuseppe

Hall of Fame Super Bronze

Re: SERVICE DHCP required for external DHCP Server required?

service dhcp should not be needed to implement DHCP relay function with ip helper address

I'm sorry but that's not correct. You need service dhcp for DHCP Relay services.

Per documentation:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12.2_52_se/configuration/guide/swdhcp82.html#wp1218221

Regards

Edison

______

Each time you rate a CSC   discussion   we'll donate $1 to the American Red Cross Haiti fund up to a   maximum   donation of $10,000 USD.

https://supportforums.cisco.com/docs/DOC-8895

Hall of Fame Super Silver

Re: SERVICE DHCP required for external DHCP Server required?

thanks Edison for your correction clearly the more reasonable answer for OP scenario (and the simplest)

Best Regards

Giuseppe

Re: SERVICE DHCP required for external DHCP Server required?

Thanks guys for the quick reply. Now I see and know where the issue was coming from.

However, is this only a need if the DHCP server is in another VLAN then the Client?

Thanks again, very appreciated!

Best Regards

Andreas

Hall of Fame Super Bronze

Re: SERVICE DHCP required for external DHCP Server required?

However, is this only a need if the DHCP server is in another VLAN then the Client?

Correct.

Regards

Edison

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