Wireless 802.11G Routers Used With OpenVMS

[vaxdecman]

Hello,
Has anyone had any success using a wireless router to route DECet or LAT over the wireless router to a PC? A wireless router typically has 4 RJ45 ports that can either connect 10BASET or 100BASET and route these signals to a wireless connected PC> I just don't know if the router will send DECnet or LAT over the wireless.
Thanks.
Greg Miller
VAXDECman

[Ian Miller.]

some routers are routers and only do IP and some routers are bridges. You want a wireless bridge. Apparently there are some but you have to research caefully. I know the WT834GT I use at home is a router not a bridge.

[Robert Gezelter]

Greg,

A 802.11g device is IP-ignorant, so long as you do not traverse the router portion of the device.

Running DECnet or LAT (or for that matter NETBUEI or NETBIOS) over the 802.11g network (which is, in reality, an 802.3 network over wireless.

Most of the SOHO 802.11b/g products are combination switches/hubs, routers, and firewalls. The firewall/router portions are most often limited to IP-based protocols.

- Bob Gezelter, http://www.rlgsc.com

[vaxdecman]

Bob,
I'm not sure I understood your answer. So are you saying that the wireless part of the router should be able to transmit LAT and DECnet since these are 802.3 protocols?

I'm using Pathworks Powerterm 525. It works from my PC to my Alpha both connected to the wireless router's RJ45 ports. But I haven't been able to get it to work by going from the Alpha to a laptop which has a wireless cord and is connected via the router.

So is it just a matter of not having the wireless network configured right on the PC then?

Thanks.
Greg

[vaxdecman]

Bob,
I'm not sure I understood your answer. So are you saying that the wireless part of the router should be able to transmit LAT and DECnet since these are 802.3 protocols?

I'm using Pathworks Powerterm 525. It works from my PC to my Alpha both connected to the wireless router's RJ45 ports. But I haven't been able to get it to work by going from the Alpha to a laptop which has a wireless card and is connected via the router.

So is it just a matter of not having the wireless network configured right on the PC then?

Thanks.
Greg

[vaxdecman]

Bob,
I'm not sure I understood your answer. So are you saying that the wireless part of the router should be able to transmit LAT and DECnet since these are 802.3 protocols?

I'm using Pathworks Powerterm 525. It works from my PC to my Alpha both connected to the wireless router's RJ45 ports. But I haven't been able to get it to work by going from the Alpha to a laptop which has a wireless PCMCIA card and is connected via the router.

So is it just a matter of not having the wireless network configured right on the PC then?

Thanks.
Greg

[Robert Gezelter]

Greg,

It may be necessary to check things with an analyzer, but in essence, yes. You can have problems if the the wireless contains a switch which tries to be too smart (particularly about LAT which DOES use broadcast service advertisements).

- Bob Gezelter, http://www.rlgsc.com

[Thomas Ritter]

Greg, I read this over a few time. I initally thought it should work. If you have a simple switch implementing Ethernet and connect two LAT or Decnet aware hosts then communications will work. You have a small scale corporate network. Now if you replace the CAT5 cable with a wireless connection it should also work, if that is all it does replace one transmission medium with another. However, neither Decnet or LAT are routeable protocols unlike IP packets which contains information about networks. Having a Router providing the connection is the problem. CISCO used to make routers which emulated LAT, we still have them at work. There are some other Router come LAT eumlators out there.
My AUS 2 cents.

[vaxdecman]

The particular wireless router I'm using is made by Motorola and it is an 802.11G 54 mbps router. I bought at Radio Shack. But I would imagine that it functions the same as Linksys or any other wireless router. I think that Linksys is made by Cisco. I don't know if Motorola makes their own router or is just slapping their name on it.

I know that back in the 80s and 90s, DEC made their own ethernet routers that did route both DECnet and LAT over baseband thickwire and thinwire coaxes. I think that it was Cisco and others that came along later and provided the ability to turn off certain protocols like DECnet and LAT. I think though with DECnet Phase V, it is routable over a WAN just like TCP/IP.

It may be possible that when PC wireless routers became popular to the general consumer, the manufacturers of these decided it is not worth their effort to include DECnet and LAT.

Anyway, I'm still trying to make sure I have everything setup correctly. If anything, I'll throw out wireless if I can't route good old DECnet and LAT!

[Robert Gezelter · Accepted solution]

Greg,

Remember, that the "Wireless Router" is really a combination of:

- A switch
- A firewall/router
- A Wireless Access Point

Conventionally, the Router/Firewall is between the WAN port and the combination of the WAP/Switch.

The only safe way to identify what is happening to to use a sniffer (Ethereal is free) and see if the packets are going out correctly on the wireless (they should).

- Bob Gezelter, http://www.rlgsc.com

[Bart Zorn_1]

Hey guys, let us keep our facts and terminology right!

LAT is not routable. There were never LAT routers. LAT can be encapsulated in an other protocol and then be routed. However, generally that yields too much latency to be useful.

DECnet, both Phase IV and Phase V, can be routed by DECnet capable routers, either host based or dedicated boxes.

IP is routable, but everybody knows that.

NETbeui is not routable, just like LAT. NETbios over DECnet, oto, is routable because it is using DECnet as transport.

That said, I can confirm that some Wireless routers do not seem to carry other protocols than IP. I have a SMC wireless router/switch and it does only IP over the wireless link. I did not (yet) investigate this further.

Regards,

Bart Zorn

[vaxdecman]

I have a Motorola PCMCIA 802.11G adapter that I just bought on one laptop running Windows XP. It lists LAT as one of the protocols it uses in addition to DECnet, TCP/IP and others. However, it does not seem to detect a LAT service from one of my Alphas.

I also have a desktop that has both an older 802.11b USB wireless adapter AND a straight PCI network adapter. This one does pick up the LAT service.

Not sure what's going on with the laptop yet. The network driver suggests that LAT should work.

BTW, I seem to remember that Digital made ethernet routers (DEMPR)that passed LAT on from one baseband network segment to another. They also had a bridge called DEBAM that did the same.

Greg Miller
VAXDECman

[Robert Brooks_1]

Greg wrote . . .

BTW, I seem to remember that Digital made ethernet routers (DEMPR)that passed LAT on from one baseband network segment to another. They also had a bridge called DEBAM that did the same.

-----------

The DEMPR/DESPR (multi- or single-port thinwire repeater) is just that -- a repeater, as is the DEREP (the "thickwire" repeater) and DEREN.

They're neither bridges, nor routers. A repeater simply extends an Ethernet/802.3 network. Devices on different sides of a repeater are said to be on the same network segment. Any traffic that is generated on one side of a repeater is propagated to the other side, even if traffic that is between systems on one side of the repeater. A repeater has no knowledge of protocols whatsoever.

In short, a repeater functions at the lowest
layer (the physical layer) of the OSI 7-layer networking model.

A bridge, however, connects separate network
segments. These segments are separate "collision domains" -- that is, a bridge will not propagate traffic from one segment to another unless the source and destination addresses of the ethernet/802.3 packet reside on different sides of the bridge.

A bridge functions at the 2nd-from-the-bottom layer (the data (or link) layer) of the OSI 7-layer networking model.

[vaxdecman]

Exactly. Thank you, Robert. I meant repeaters. It had been awhile, about 10 years using the DEREP and the DEBAM.

Do you know if DECnet Phase V can route DECnet and LAT on top of TCP/IP? Maybe that will allow transmission of LAT over a wireless router? Thanks.

[Robert Gezelter]

Greg,

LAT cannot reliably be tunneled, period. The timeouts are set for far shorter intervals. Any disruption or latency on the IP link will break all of your LAT connections.

A bridge, abset special configuration, as Bob Brooks noted, is a separate collision domain, and signal regeneration (as opposed to a repeater, which is basically just a signal regeneration device). It should not, strictly speaking, do any filtering, or be aware of anything above the Ethernet layer.

To get all of the software issues out of the problem, use Ethereal (or another scanner) to check if the LAT multicasts are being received BOTH on the wired switched ports and the wireless signal.

If the multicasts are being received on the wired network, but not on the wireless network, then I strongly suspect that the wired/wireless router is, despite the specifications, filtering traffic between the wired and wireless segments, which IMHO, it should not do.

The answer may very well be to obtain either:
- a different brand of SOHO router/firewall, without this anomaly; or
- purchase a strict WAP, which just broadcasts all packets on the Ethernet over the wireless

Wireless security is, of course, an entirely separate issue.

- Bob Gezelter, http://www.rlgsc.com

[Hoff]

If you want DECnet DDCMP, LAT or any other network protocol (other than IP, or DECnet-Plus over IP) operating over a wireless connection, you must use a wireless bridge (point-to-point or otherwise) or an 802.11-class wireless access point (AP), or any embedded router within your device must support your target protocol(s).

Until and unless the router supports your target protocol(s) or until if your protocol(s) can be successfully encapsulated or tunnelled (iSCSI is basically a form of IP encapsulation for SCSI, for instance), you do not want a router. A router that doesn't route your particular protocol is little better than an expensive terminator, after all.

Network devices known as bridges, repeaters, access points, hubs and switches all lack a protocol router; all traffic is passed through per the rules of the OSI layer(s). Further, these are all link layer or network-layer devices. (There can be and are differences, for instance, between how a repeater (physical layer) and a switch (link layer) actually function, however these differences aren't immediately relevent to this discussion.)

Where the Wireless LAN (WLAN) confusion "fun" arises: some wireless routers can and do provide an AP (and a wireless router almost inherently has to include some form of an AP; a physical layer network connection), but these may or may not be accessable; the AP may or may not allow bridging other protocols around the router's stack.

APs also obviously depend on the existance of a protocol-specific router logically configured on the network behind the AP, which is what you want when the device does not contain a router. An AP is directly akin to an 802.3 NIC, in other words, without the host protocol stack.

Network security is another issue (and an obvious issue with any wired or wireless network), as an open or unlocked AP can obviously allow full access into the network behind the AP.

I do not immediately have any AP device recommendations available, which I expect is the root question here.