[HECnet] SIMH + Multiple interfaces + DECnet

Paul_Koning at Dell.com Paul_Koning at Dell.com
Sat Dec 29 11:37:00 PST 2012


On Dec 29, 2012, at 2:34 PM, Johnny Billquist wrote:

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. :-)

I quite agree with you.   "Routing" nodes are routing...   I just disagreed with the comment that VMS nodes don't understand bridging.   They don't DO it, but they understand it...


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


Yes, that's what I meant.   

	paul



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