SERVICE DHCP required for external DHCP Server required?

Answered Question
Mar 31st, 2010
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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!

Correct Answer by Edison Ortiz about 7 years 3 weeks ago

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


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Giuseppe Larosa Wed, 03/31/2010 - 08:14
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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

Correct Answer
Edison Ortiz Wed, 03/31/2010 - 15:01
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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


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Giuseppe Larosa Wed, 03/31/2010 - 15:17
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thanks Edison for your correction clearly the more reasonable answer for OP scenario (and the simplest)


Best Regards

Giuseppe

Andreas Birlenbach Thu, 04/01/2010 - 00:13
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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

Edison Ortiz Thu, 04/01/2010 - 06:19
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However, is this only a need if the DHCP server is in another VLAN then the Client?


Correct.


Regards


Edison

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