Another possible inter-node communication system

Harald Milz hm at
Thu Mar 5 22:55:25 MST 1998

CC to the linux-ha list because IMHO this is interesting for the whole

On Thu, Mar 05, 1998 at 06:08:24AM +0000, alanr at wrote:
> > Hi,
> > 
> > > It seems that another possibility for internode communication
> > > (keep-alive messages) would be IrDA.  It might be worth mentioning in
> > > the FAQ.
> > 
> > Albeit very expensive and overpowered :-)
> > 
> > Ciao,
> > hm
> I was assuming that you would only use this if you have motherboards which have
> the IrDA drivers onboard (as do several I've seen recently).  Then it's only a

Ah, now I get the picture. This leaves two questions open (at least for

- don't the IrDA ports normally take one of the onboard serial interfaces?
- what is the maximum distance for an IrDA link (and what would happen if
  someone walks between the nodes, equivalent to what happens if someone
  unplugs the serial cable, which leads to a network_down event for that
  interface and node.)

> little money for the LED assembly.  It's cheaper than an ethernet port, and it
> doesn't take up a slot (if it's on the motherboard).  A shortage of slots seems

IrDA is not an alternative to an ethernet port because ethernet doesn't run
non-IP heartbeat. :-)

> to be a problem with Linux-HA.  This would potentially allow more computers in

This is correct. Normal 4+4 (1 shared) PCI/ISA boards would be sufficient
for simple solutions (2 PCI storage adapter cards, 2 PCI 100TX cards for
example). There are also multi-port cards for SCSI and Ethernet out there
but I don't quite like the idea of using them for a HA solution because
these cards have a SPOF represented by the single PCI brigde chips that are
normally on them. 

> an HA cluster than if you use the onboard serial ports.  Of course, this
> assumes that you have a driver for the chip sets, etc.
> 	-- Alan Robertson
> 	   alanr at


Reality is for those who can't face Science Fiction.

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