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Title
Optiplex 9010 PXE error 51 on Cisco switch -
Description
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Optiplex 9010s fail to PXE boot on the switch.
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Switch is a Cisco 3560.
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9010s successfully PXE boot to the RSA and K2000 at the K2000's home location.
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9010s successfully PXE boot to the RSA at the remote location, off the switch.
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A Latitude and an Optiplex 745 PXE boot to the RSA at the remote location, on the switch.
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9010s gets an IP from the DHCP, but fail PXE boot with this error.
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Error: PXE-E51 No DHCP or DHCP Proxy Offers
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Cause
Spanning tree is in use, but portfast was not enabled on the switch. Thus DHCP times out waiting for the network spanning tree to be built.
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Resolution
In the switch configuration, enable Portfast for the needed ports.
Additional info on Spanning Tree PortFast: http://www.cisco.com/en/US/products/hw/switches/ps679/products_configuration_guide_chapter09186a008007d779.html#32976