Using a wireless NIC with Avanti requires special handling. Try one of the following options:
•Create a bridge TAP adapter.
•Set the virtual Alpha NIC MAC address to the same MAC address as the wireless card. THIS SOLUTION IS INCOMPATIBLE WITH DECNET PHASE IV and DECnet Phase V running in compatibility mode. DECnet Phase IV will forcibly change the virtual Alpha NIC's MAC address to the DECnet phase IV address (AA-00-04-xx-xx-xx), breaking the wireless connection. Do not share the same TCP/IP address between the wireless host and the virtual Alpha system or it will confuse both systems.
Wireless Ethernet looks like Ethernet, but it isn't Ethernet. Using a wireless NIC with Avanti can be problematic. Here’s why.
If the standard MAC of the Avanti NIC is used and the virtual NIC is attached to a wireless controller, then any packets which are not addressed to/from the "registered" PC's wireless MAC address may be legally dropped by the wireless router to conserve bandwidth.
The best way to debug a wireless router connection is to run a packet sniffer like WireShark on the host PC and watch the packet traffic, while also running a packet sniffer on a wired PC on the network to see if all the packets are traversing the wireless link correctly. It almost never operates as expected, because wireless routers are allowed to drop non-essential packets to conserve bandwidth. Non-TCP protocols like DECnet tend to get axed because modern routers, particularly consumer-grade routers, usually don't need to deal with non-TCP packets.
Spoofing the MAC address by assigning the PC wireless MAC to the Avanti NIC will avoid the wireless packet dropping, but only if DECnet Phase IV or DECnet Phase V (DECnet OSI) running in compatibility mode are not in use. DECnet Phase IV forcibly changes the hardware MAC to a DECnet-encoded value, which overrides the manually configured Avanti MAC address.
Spoofing the MAC will work when only TCP/IP is in use on the Avanti system, since the Avanti NIC will see all the matching MAC IP packets and throw out the incorrect IP-addressed packets.
MAC spoofing will work for DECNET Phase V in non-compatibility mode, LAT, and Clustering if the router/card combination does not filter out non-TCP protocols. DECnet Phase V will display a lot of unknown protocol messages to the console. Under OpenVMS, using a SET TERM OPA0: /NOBRO/PERM will hide the messages, or NCL can be used to disable the warnings.
It is possible, but difficult, to support DECNET IV use over wireless. A very few wireless routers support bridge mode, which passes all traffic over the wireless link as through it were a real Ethernet. For wireless combinations that can’t bridge, the MAC of the wireless NIC can be manually changed to a DECNET IV AA-00-04-style MAC address by using a utility like SMAC or similar reverse-spoof techniques. This will work as long as the wireless router/card combination supports non-TCP packets, but it is tricky to get DECNET IV started in the reverse-spoof environment, since it ‘panics’ when it sees the duplicate DECNET source address on the wire during protocol startup.
Some router/wireless card combinations will work flawlessly to route non-registered MAC addresses, most will not.
