[HECnet] Connections?

[Brian Hechinger]

OpenVSwitch for the win!

On Sat, May 5, 2018, 14:51 <dwe-6006 at philtest.org> wrote:

> The case of multiple simulated systems talking to each other as well as
> talking to the host is pretty simple but it does require that the guests
> and the host all have unique IP addresses. In this case just set up
> software bridge that connects tap devices for each guest to the physical
> Ethernet adapter for the host. The guests can have unroutable addresses as
> long as the host understands that they exist on the bridge. It’s less ugly
> if the host has a secondary address in the unroutable subnet but brute
> force will work nicely if necessary.
>
>
>
> Where the multiple simulated systems need to speak to each other and the
> host and the Internet, the easy way is the tap and bridge solution  but all
> the devices require unique and routable IP addresses.  Where routable IP
> addresses are at a premium then the tap and bridge alone will not work and
> the options range from NAT (which can be painful) to  using one of the
> software virtual routers like dynamips running a suitable version of
> Cisco IOS or the DD-WRT appliance (which can also be painful)
>
>
>
> Dave
>
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> *From:* owner-hecnet at Update.UU.SE [mailto:owner-hecnet at Update.UU.SE] *On
> Behalf Of *Mark Pizzolato
> *Sent:* Saturday, May 5, 2018 1:56 PM
> *To:* hecnet at Update.UU.SE
> *Subject:* RE: [HECnet] Connections?
>
>
>
> Hi Mark,
>
>
>
> I’m not understanding what you saying here.
>
>
>
> Are you suggesting that on a single host system, you’ve got multiple
> independent simulators running which all are using the same IP address as
> the host system? And, if true these devices can then, not only uniquely
> communicate with remote systems (on the Internet say), and also to each
> other AND the host system?
>
>
>
> -          Mark
>
>
>
> *From:* owner-hecnet at Update.UU.SE [mailto:owner-hecnet at Update.UU.SE
> <owner-hecnet at Update.UU.SE>] *On Behalf Of *Mark Abene
> *Sent:* Saturday, May 5, 2018 10:45 AM
> *To:* hecnet at update.uu.se
> *Subject:* Re: [HECnet] Connections?
>
>
>
> This is an often misunderstood generalization, with some people able and
> others not. I remember this being true on *BSD. You could not connect to a
> simulated IP on the same host. It *used* to also be true on Linux, but is
> no longer the case for some time. On my ubuntu server where I run dynamips,
> simh, and klh10, all on bridged taps, I can telnet to all instances, even
> locally.
>
>
>
> -Mark
>
>
>
>
>
>
>
> On Sat, May 5, 2018, 12:27 AM Johnny Billquist <bqt at softjar.se> wrote:
>
> On 2018-05-05 03:39, Robert Armstrong wrote:
> >>since once Multinet grabs the interface, I can’t get to the underlying
> > host.
> >
> >    Actually I think it’s a limitation in simh and the pcap library – the
> > simh guest OS can’t talk to the host OS on the same interface.  You can
> > work around the problem with a TAP device.  Check the archives for the
> > simh mailing list – it’s been discussed many times before.
>
> No. That is not correct. I run simh myself on a machine where I have
> both the native host and simh talking on the same ethernet. And they are
> both reachable by other hosts.
> The OP must be doing something else funny.
>
>    Johnny
>
> --
> Johnny Billquist                  || "I'm on a bus
>                                    ||  on a psychedelic trip
> email: bqt at softjar.se             ||  Reading murder books
> pdp is alive!                     ||  tryin' to stay hip" - B. Idol
>
>
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