On 2017-03-11 22:33, Tim Stark wrote:
Yeah.
I believe so. That is possible to replace CI/DSSI physical layer with UDP over
IP multicast to embed SCS/MSCP packets to other hosts and HSCs at once.
Of course this is doable. The network part itself is not even hard. The
big work is actually implementing the CI controller emulation. Once you
have the packet to send out, you just send it.
That's why Charon-VAX already emulates virtual CI and HSJ for VAX 66x0
emulation. I read Charon documents and learned that emulated CI uses SCS/MSCP
over IP method.
Which should be a pretty obvious solution.
That is same way like BITNET over TCP/IP and DECnet over TCP/IP (HECnet
provides bridge adapter software).
One should remember that my bridge is nothing comparable to this. All it
does is bridge two ethernet segments together, so that they appear to be
one. It's plain ethernet on both sides, so it's a really stupid simple
thing. Packets on one segment gets injected into the other segment.
Since it's ethernet on both sides, nothing more needs to be done.
Doing CI on ethernet would be a much more complicated challenge. CI over
IP will be easier, since the capabilities of IP are better at handling
the requirements that CI will demand.
But you still need to emulate the rest of the CI hardware, which
contains both the host interface parts, and also possibly some
addressing and filtering, and the actual transportation of the bits.
That’s why I studied Computer Networking and learned lot about ISO layers at
university.
Also about bridging and routing methods.
I hope you also learned that the ISO layers are a good theory, but is
not applicable to TCP/IP, which is not designed according to the ISO layers.
Johnny
Tim
-----Original Message-----
From: Mark Pizzolato [mailto:[email protected]]
Sent: Saturday, March 11, 2017 11:19 AM
To: Tim Stark <[email protected]>; [email protected]
Subject: RE: [Simh] LAVC
On Saturday, March 11, 2017 at 5:49 AM, Tim Stark wrote:
Thanks for many replies. I learned a lot about VAX clustering. I will
use multicast Ethernet for clustering. I have more one question. Is
that possible to emulate HSC controllers with LAVC access?
When Matt Burke and I were discussing the CI concept, we picked IP Multicast as
transport for the very specific reason that all modern host systems will have
natural user mode programming access to implement this functionality.
Attempting to create your own Ethernet multicast protocol (non-IP based) will
have portability complexities on different platforms due to the fact different
platforms have varying support (and potentially require privilege) to present
and/or receive raw Ethernet frames to/from a LAN.
- Mark
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