LKBEN10849: No DHCP address at PXE-Boot with RIS


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LKB | Created: 02/04/2020 | Version: 1 | Language: EN | Rating: 0 | Outdated: False | Marked for deletion: False

Author: Wim Peeters - Keskon GmbH & Co. KG

Latest update: 05/10/2020 | Comment:


Symptom

You cannot get a DHCP address when booting with PXE.

Cause

You cannot get a DHCP address when booting with PXE.

Solution

When a client booting with PXE receives no DHCP address, the problem may be up to a faulty configuration of the switch. This becomes clear if the same client functions with Windows without any trouble.

The cause of the malfunction of DHCP is a delay in the connection building of the switch. The reason for this delay is the activated "Spanning Tree" at the switch. When building a conncetion the switch checks if a "Loop" is existent. The operation takes approximatly 10 to 15 seconds. In this time the link already physically exists but all data (like DHCP-requests) are discarded. To solve this problem either insert a hub between the switch and the client or disable the "Spanning Tree" method at the switch.

Note: Some CISCO switches have the same problem. To solve the case, activate the "Portfast" option.

About the Author

Wim Peeters is electronics engineer with an additional master in IT and over 30 years of experience including time spent in support, development, consulting, training and database administration. Wim has worked with SQL Server since version 6.5. He has developed in C/C++, Java and C# on Windows and Linux in different European countries and different European languages. He writes knowledge base articles to solve IT problems and publishes them on the Lubby Knowledge Platform where he is one of the most important contributors and the main developer.

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