Archived from groups: alt.video.ptv.tivo (
More info?)
Sorry, I was at work and just saw the replies, which i greatly
appreciate. Jim, I have the DI-624 same as you and I found the option
to trun on "g" only and I see what you mean about that. Like I said in
my origianl post witht he d-link "b" adapter iwas using I think it was
about 1 1/2 hours to transfer a 1 hour show. does this sound right?
with the new dwl-g120 adapter it says that it is goignto take 3 hours.
My big questionwas that on the TiVo website they said the dwl-g120
version B2 was compatible. after i got it home i saw on the box that it
was a B1. It looks the same as the B2. does the hardware version make
that much difference to where the speed would be that much slower? all
I did when I connected it to my TiVo was plug it in the USB port and
then the Tivo restarted itself. Should I have done something different?
Is there a way to tell which device the Tivo thinks is conneceted so i
can make sure it is using the right driver?
Thanks for all the replies I greatly appreciate it. Steve.
Randy S. wrote:
> Comments interspersed, please see
>
http
/www.proxim.com/learn/library/whitepapers/parameters_802.11g_performance.pdf
> for one source of documentation:
>
> Jim wrote:
>
>> I can't be 100% positive here, but I can conjecture a pretty good guess.
>
>
> Well, your guesses have some bearing with reality, but fall short of the
> mark in several aspects.
>
>> Presumably your current wireless network supports "b" and "g". Most
>> consumer model routers from Netgear, Linksys, and D-Link (esp.
>> D-link), do
>> NOT perform as efficiently when running in mixed mode, i.e., support
>> 'b" and
>> "g" clients concurrently.
>
>
> This is true, though I want to point out (and will back up further down)
> that you are overstating the effects.
>
>> Although supported, it's with caveats (that the
>> vendor usually doesn't make much mention of, for obvious reasons).
>
>
> Mostly because the issue is much too complex to the casual user, and
> doesn't really matter that much to them.
>
>> First,
>> when running both "b" and "g" clients concurrently, most routers will
>> DOWNGRADE the "g" clients to "b" performance, simply because it can't
>> actually do two things at once, it's either "b" or "g", and if a "b"
>> client
>> is transmitting when a "g" client also wants to transmit, rather than
>> wait
>> for all "b" transmissions to cease, the router simply forces the "g"
>> client
>> to run in "b" mode (or else does make it wait).
>
>
> This is sort-of true. It *is* true that only 1 device on a given 802.11
> collision domain can broadcast at once, so that when your "g" device is
> broadcasting, your "b" device must wait. But this happens even if you
> have all "b" devices or all "g" devices. What is *not* true is that
> your "g" devices are forced to transmit in "b" mode. The only change
> that your "g" device has to do is use a longer "slot" time (20
> microseconds vs. 9 microseconds) to be compatible w/ the "b" device slot
> times. This has an effect, but it's probably about a 20% penalty, not
> the 80% penalty that would be incurred from going from 54 Mbps to 11 Mbps.
>
> The one situation where you *may* see such a high penalty is where you
> have *2* overlapping mixed wireless collision domains (i.e. 2 wireless
> routers) on overlapping or identical channels, but this is not the
> typical residential wireless scenario, it's more of a problem for
> corporate networks.
>
>> Second, in order to improve
>> the situation, the typical "g" router (a good one anyway, like my D-Link
>> DI-624) supports something called "802.11g Only Mode". It may go
>> under some
>> other name w/ other products, but if it's there, its under the wireless
>> configuration section (e.g., w/ Belkin F5D7230-4 and F5D7231-4
>> routers, it's
>> called "54-G Only"). Why does this exist? Because when you enable this
>> feature, the router doesn't have to waste processing cycles to check the
>> channel for "b" traffic before transmitting every time! Instead, "b"
>> clients are simply rejected, and only "g" clients accepted, and
>> because its
>> ONLY "g" clients, the router is much more efficient. Most routers level
>> this feature disable by default, for maximum compatibility. But if
>> you ONLY
>> have "g" clients, it should be ENABLED for maximum performance.
>
>
> I don't think I can agree that it's *much* more efficient. The shorter
> slot time does improve throughput, but your *maximum* gain is
> theoretically about 33%. While this is significant, it certainly
> doesn't explain why his "g" adapter is *slower* than his "b" adapter
> was. Also, if you look at past threads, maximum Tivo throughput is
> nowhere near what 802.11g can support, but is instead throttled by
> internal processes in the DVR (most likely encryption duties).
>
>> Secondarly,
>> it's a respectable security measure, one less class of clients that can
>> appropriate your wireless system!
>
>
> Calling it a *respectable* security measure is a stretch. Since most
> new devices use 802.11g I'd say it's pretty much a *marginal* security
> measure, i.e. it doesn't hurt, but it doesn't do much good either.
>
> <snip>
>
> My views on this would be buy "g" equipment when you buy new stuff, but
> don't spend money on upgrading existing equipment if it works fine now.
> Mixed mode networks have some penalty involved but it isn't likely
> something that will impact you greatly.
>
> The *real* speed gains on Tivo DVR transfers are gained by hacking the
> box and removing the encryption processes totally. Others here can tell
> you more about that, but it's not nearly as simple as upgrading a
> wireless adapter.
>
> Also, "g" won't be the fastest wireless protocol on the block for very
> much longer. 802.11n (touted mostly as "MIMO" right now) has not been
> ratified yet, but pre-ratification products are already coming out.
> These devices are basically very similar to 802.11g (and are backward
> compatible, fortunately) but use multiple receivers and multiple
> transmitters in order to increase range and reduce deadspots. They
> reportedly work very well, I'd definitely recommend getting them when
> they become widely available.
>
> Randy S.
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