I recently posted a article named “kickstart oracle unbreakable linux” where I explained the reason why we where moving from RedHat Linux to Oracle Unbreakable Linux and how we used kickstart to install Oracle Unbreakable Linux at SmartApps.
In this post I explained that initially we had some problems with the PXE booting of machines to install Linux via the network. The problem is that we have redundant network links to ensure network uptime in case of a cable failure. To make sure that network traffic is looping in redundant network loops we have configured a Spanning Tree Protocol (which is a OSI layer-2 protocol) to ensure that no looping is done.
If your switch is doing spanning tree calculations, you’re not forwarding any traffic at all within the first 50 seconds and that may exceed the timeouts in your PXE setup. On your switch’s ports, try using "spanning-tree portfast" to jump immediately to a forwarding state.
To configure your switch (in our case a Cisco WS-C3548-XL) you have to do some settings. I will explain the way to do this here:
Login to the Cisco switch go to enable. To do so you need to enter a password twice:
Connected to Cisco C3548XL switch pubswt11 at colo [ STORAGE ] PUBCAB06
User Access Verification
After this you are logged in in the switch in such a way you are able to do some settings. Now we will have to make some changes to port number 21. We have to set the spanning-tree setting to portfast and we like to set the speed to 100 and duplex to full. This is done by going to the configuration mode for the interfaces.
pubswt11(config)#interface FastEthernet 0/21
Now we can set the needed setting by entering the following commands:
You leave the configuration mode by a key combination of Cntrl+z. now you can save the configuration with a wr command and your done. Now PXE boot should be successful.