serial over lan

Donald Becker becker at
Sat Feb 22 12:00:50 PST 2003

On Sat, 22 Feb 2003, Don Holmgren wrote:

> On Fri, 21 Feb 2003, Donald Becker wrote:

> > On Fri, 21 Feb 2003, Dale Harris wrote:
> > > Just wondering if anyone is doing anything with Serial over LAN?  I
> > This is IPMI serial port redirect.
> > While it's not specifically part of IPMI 1.5, most IPMI 1.5 implementations
> > include it.
> >
> > Power control and serial port redirect (BIOS setup and boot status
> > monitoring) are the features that makes IPMI 1.5 really compelling
> > for cluster hardware (albeit with a ugly underlying implementation).
> The serial port redirect available on the IPMI option cards on
> SuperMicro motherboards is significantly flawed,

It's always an ugly implementation.
Originally IPMI was intended as a low speed, serial line management
control.  To avoid having an additional connector, it evolved to
multiplex on an existing serial port connector.  Once the Baseboard
Management Controller (BMC) had access to the serial port and a network
connection, it was a simple evolution to forwarding serial port traffic
over the network.

> at least in the current implementation of the firmware.  They are
> evidently using the BMC processor to snoop the memory area used by the
> standard BIOS text console.

I'm guessing that's not quite what is happening.  The main CPU is
looking at the text console memory, and converting that to serial port
output.  The BMC is then forwarding the serial port output.  If I'm
right, the fix is a main BIOS update rather than a BMC firmware update.

> Also, even in the BIOS screens the tool is almost useless
> because of slow performance and dropped characters.

It's a hideous, semi-polling implementation, but it shouldn't drop
characters if configured correctly.  But it does require expertise to
configure so that it works...

> Now the question - the ability to do remote reset and power cycling in
> IPMI is a great feature.  I've been doing this for several years, going
> back to the old Nightshade and Lancewood motherboards with their IPMI
> access over the EMP, and now via the ethernet portal specified in the
> IPMI 1.5 specification.  I'm currently using a Java utility which comes
> with the IPMI option card to issue the IPMI commands.  However, the
> utility can't be scripted and is very cumbersome to configure.

Yup.  There are several other similar programs.

I'm guessing that you are looking for stand-alone tools that you can
download, and the extensive support that you will need to get your
specific configuration working, all provided for free.  I don't think
that you will find that today.

> Does anyone know of available code to do the IMPI 1.5 communications
> over TCP/IP?  OpenIPMI at SourceForge doesn't seem to address this (I
> may be wrong, but it seems to only handle local access to the BMC via
> the most commonly implemented internal mechanism, KCS).

You will need
  - both KCS and MCS kernel drivers,
  - a program to initialize the IP address on the clients,
  - a user-level library layer to send commands and 
  - stand-alone commands.

It's been done...

Donald Becker				becker at
Scyld Computing Corporation
410 Severn Ave. Suite 210		Scyld Beowulf cluster system
Annapolis MD 21403			410-990-9993

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