[Info-vax] Wireless networking for my home xp900

[John Wallace]

On Aug 17, 9:50 pm, Rich Jordan <jor... at ccs4vms.com> wrote:
> On Aug 17, 1:53 pm, John Wallace <johnwalla... at yahoo.co.uk> wrote:
>
>
>
> > On Aug 17, 4:35 pm, Jojimbo <jjgessl... at gmail.com> wrote:
>
> > > Due to some residential reorganization, my xp900 will be moving
> > > further away from the network hub.  This will make having an actual
> > > wire very inconvenient for network connectivity.  Is there some device
> > > I can use to let the xp900 join my already established wireless net?
> > > Any suggestions appreciated.
>
> > > Thanks,  Jim
>
> > You've already got an existing Access Point (AP) so I'm not sure about
> > Ian's suggestion you need another AP.
>
> > I've just abandoned powerline networking. The kit I had, some Zyxel or
> > other, suffered excessive packet loss between upstairs and downstairs.
> > As I understand it, there are very few chipsets which do this
> > powerline game, and they just modulate Ethernet packets onto the mains
> > wires, with no additional error checking and correction, in particular
> > no forward error correction. Thus if the received signal is poor, bits
> > are corrupted and therefore packets will be lost, which leads to
> > retransmission delays with TCP, and to completely lost data with UDP.
> > Web browsing was lumpy, DNS requests would fail (DNS = 3 retries
> > only?) and I couldn't make VNC connections stay up very long, for
> > example. You may have better luck,  but based on my experience I'm not
> > recommending it. Because it's not doing anything IP-oriented it may
> > offer the chance to use non-IP stuff such as DECnet, LAT, clusters,
> > etc.
>
> > The reason I had the little powerline network was to connect the LAN
> > switch in the upstairs workroom with the AP/router connecting to the
> > outside world. Prior to the powerline I had a Linksys "Wireless
> > Ethernet Transceiver" WET11 connecting the upstairs switch to the
> > downstairs router. It had ye olde security (WEP not WPA) which is why
> > I wanted it replaced.
>
> > Anyone able to shed more light on stuff for this which does work OK
> > with non-IP traffic?
>
> I wonder if you just had wiring problems of some kind, or if your
> particular powerline equipment had issues.  I've watched for problems
> at home and except for weather events that cause power fluctuations,
> and (in one location) when our air conditioner cycles on, I've
> recorded no errors.  The overall throughput does vary a bit, for
> reasons not making themselves known via monitoring (I get 9-10 Mbps,
> not the rated 14).
>
> I have had to unplug and replug my 'central' bridge twice in the last
> two years to bring the net up after a power outage and messy recovery,
> but thats it; it just runs.
>
> The low-end Netgear units use 56-bit DES encryption, so its not overly
> secure, but then the 'area' of vulnerability is also smaller, and
> someone has to connect your (or a close neighbor's) power wiring to
> intercept.
>
> In my case I replaced a pair of DEC Roamabouts in a bridge
> configuration; the original 915MHz Wavelan units that peaked at
> 2Mbps.  They worked just fine, though slow, but dragging around that
> contraption (on a board, with power supply, antenna, etc) wherever I
> wanted a netcam got to be a real pain.  And that had no encryption
> (though I doubt many wardrivers are equipped to detect or hack 915MHz
> signals!)

I wonder too whether my problems were unrepresentative.I plugged the
kit in and at first it did appear to "just work" (no configuration
necessary) but after a while Wireshark led me to conclude that my
lumpy browsing and dropped VNC connections etc were caused by dropped
packets,. Prior to this change, I'd had the home network stable for
several years, initially with a Linksys WAP11 reflashed as D-Link
DWL900 as AP client and then, when that broke, with a WET11 as AP
client.

I do have quite a lot of kit with switched mode PSUs, which in my case
is mostly old geek stuff, much of which is (not surprisingly) in close
proximity to the powerline boxes. Many other folks have lots of SMPSUs
in modern consumer electronics - TVs, set top boxes, you name it.
Hence my caution.

I didn't fancy disconnecting items one by one, and checking for
improvements, especially as this Zyxel had no error counters or other
quality indicators, although the HomePlug 1.0 folks (including Zyxel?)
do claim they have forward error correction, automatic repeat
requests, etc [1].

My next purchase will probably be an "AP client" but the vendors say
you need to make sure the matching AP is compatible (eg can't mix and
match Netgear and Linksys), which is likely to mean binning my current
AP/router and thus spending more than I really can afford right now.
Mind you, I'm using a Linksys WET with a Billion AP/router and it
works. I thought WDS (WiFi Distribution Services) was supposed to fix
mixed-vendor stuff but it doesn't really appear to be obvious that it
has.


[1] http://www.homeplug.org/products/whitepapers/HP_1.0_TechnicalWhitePaper_FINAL.pdf