[HECnet] SIMH + Multiple interfaces + DECnet

[Johnny Billquist]

On 2012-12-29 20:29, Paul_Koning at Dell.com wrote:

On Dec 28, 2012, at 4:44 PM, Johnny Billquist wrote:

...
Yes, VMS can route packets. Yes, all ethernet interfaces under DECnet phase IV will have the same MAC address. No, VMS have no idea of the concept of a bridge. And if you bridge two ethernet segments together, and VMS sits on both those segments, bad juju happens.

Actually, DEC nodes are quite aware of bridging -- DEC after all invented LAN bridging.   The thing that you have to get right is that the multiple DECnet phase IV interfaces *must* be on distinct extended LANs.   The changed MAC addresses are the reason why.

And I still claim that they are not bridging, but routing.
They do not ignorantly repeat any packets received on one interface out on other interfaces, which is what a bridge does.

I'd happily discuss this further, if you really disagree with me. :-)

This changes with Phase V, since that doesn't change the MAC address (if it doesn't have to be Phase IV compatible, that is).   Also, unlike Phase IV, Phase V supports end nodes with more than one interface.

Right. Phase V is a different story again. And I assume you mean endnodes with more than one active interface, as phase IV endnodes can also have more than one interface, but only one can be active.

	Johnny