openstack/ironic
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Document PXE with Spanning Tree in troubleshooting FAQ

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STP can cause issues with DHCP and PXE on some switches, and there is an
easy way to resolve it by change the switch port STP mode. This patch
documents the issue and the solution with an example.

Change-Id: I77aa88ec1c6d8d90e57d22365e488ecd704fe64f
This commit is contained in:
Sam Betts 2017-02-15 10:40:05 +00:00
parent 57cd68caf8
commit 142ae0ea8c
1 changed files with 17 additions and 0 deletions
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17
doc/source/deploy/troubleshooting.rst
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@ -292,3 +292,20 @@ distribution that uses ``systemd``:
journal
ip_addr
iptables
DHCP during PXE or iPXE is inconsistent or unreliable
=====================================================
This can be caused by the spanning tree protocol delay on some switches. The
delay prevents the switch port moving to forwarding mode during the nodes
attempts to PXE, so the packets never make it to the DHCP server. To resolve
this issue you should set the switch port that connects to your baremetal nodes
as an edge or PortFast type port. Configured in this way the switch port will
move to forwarding mode as soon as the link is established. An example on how to
do that for a Cisco Nexus switch is:
.. code-block:: bash
$ config terminal
$ (config) interface eth1/11
$ (config-if) spanning-tree port type edge