Now that I’m finding time to focus on my passion – manageability, I’ve been able to spend some time working on some documents. This is the announcement for my most recent whitepaper.
This paper discusses the problem that occurs when a server power action (on/off/reset) occurs and the Ethernet link is momentarily lost when the network port is being used by the BMC/MC. Losing the link is a normal part of this process, it usually goes down once or twice during the power up sequence, once when the platform is initialized and again when the software driver loads and initializes the network device. This loss of link usually lasts much less than a second each time.
During normal operations a momentary loss of link causes no issues. However if you have the Spanning Tree Protocol (STP) deployed in your network, even a momentary loss of physical link can cause a loss of network connectivity to the BMC for over a minute.
This can present some pesky problems if say for example you rebooted your server so you can go do some BIOS configuration using KVM or Serial over LAN (SoL); if the connection is out for a minute or more, it is very difficult to press the keys to get into BIOS setup from your remote management console.
Intel® Ethernet devices have a feature called ‘Critical Session’ which the BMC can configure, which will keep the link up during these transitions, thus maintaining any active connections to the BMC.
To learn how to use this feature, I invite you to read the whitepaper: