User manual

Microsoft Windows™

You can also refer to host network adapters in the

attach command by their UUID-based names, i.e. in

format

\Device\NPF_{UUID}.

Only Ethernet NICs and virtual Ethernet adapters such as Microsoft Loopback Adapter can be attached

to XQ or XQB for mapping virtual DEQNA or DELQA adapter. Host WiFi interfaces might superficially look

similar to Ethernet interfaces but they are actually not Ethernet and cannot be used for VAX MP or SIMH

Ethernet networking.

By the way of example, let us say XQ is bound to the host machine’s Ethernet adapter, and this host

adapter is assigned IP address 192.168.1.100; and XQB is bound to MS Loopback Adapter that is

assigned address 192.168.3.1. Then when configuring TCP/IP Services for OpenVMS you can define

interface QE0 (bound to XQ) to have IP address 192.168.1.200; and interface QE1 (bound to XQB) to

have address 192.168.3.200.

This set-up will configure two subnets.

One subnet is private between VAX MP and the host machine and runs virtual wire from the host’s MS

Loopback Adapter (192.168.3.1) to VAX MP’s XQB (192.168.3.200). Conversely, you can access VAX MP

from the host at address 192.168.3.200. You can access the host from inside VAX MP at address

192.168.3.1. There can be more than one instance of VAX MP running on the local machine and

connected to this subnet (with addresses let us say 192.168.3.201, 192.168.3.202 and so on), likewise

there may be other virtual machines (such as other simulators or VMware instances) running on the

local host and connected to this private subnet, but this subnet is totally inside the host, unless you set

up a routing between this inner subnet connected to loopback adapter and an exterior subnet.

The other subnet is on the physical wire. Both host machine and VAX MP are connected to the physical

wire by host’s NIC they share. Host OS will generally utilize the network card to send Ethernet packets

with sender’s MAC address field in the packet set to the physical card’s own MAC address. Whereas VAX

MP will be sending Ethernet packets with sender’s MAC address field set to MAC address of virtual

adapter defined in startup script (e.g. 08-00-2b-aa-bb-c1 in the example above).

In addition, VAX MP

will be sending IP packets with sender’s IP address set to 192.168.1.200, whereas host OS will be

sending as 192.168.1.100.

Thus even though host OS and VAX MP share the network card, they will be sending Ethernet packets to

the wire as two different machines.

On the receiving side, since VAX MP puts the card is in promiscious mode, both host OS and VAX MP’s

virtual DELQA controller will receive all packets on the wire sent by other hosts. They will filter the

packets and process only those packets that they need, i.e. host OS will generally pick up the packets

destined for the card’s MAC address (and for IP 192.168.1.100) whereas VAX MP will pick up the packets

destined for DELQA virtual MAC address (and IP 192.168.1.200). Packets that were broadcasted to the

subnet or sent to any matching multicast address will be picked up by both host OS and VAX MP.

DECnet and VAXcluster protocols will further change effective MAC address to the value in range

AA-00-04-00-xx-yy derived from DECnet node number and SCS ID.