802.11 b/g compatibility?

Archived from groups: alt.internet.wireless (More info?)

Hi wireless fans... long time listener, first time caller...

We've enjoyed a nice wireless LAN with a Linksys BEFW11S4 (firmware v
1.45z, an 802.11b router) providing a gateway to cable internet,
serving a few laptop PC's:
(1) Windows XP home, internal Broadcom 802.11g adapter
(2) Windows XP home, external Linksys WPC11 (802.11b) adapter
(3) Windows XP pro, internal LanExpress 802.11b adapter
(4) Windows XP home, internal 802.11g adapter
.... and a couple wired clients

The router is configured for MAC address filtering, but no WEP.

Everything was groovy for almost a year. Typical throughput was on the
order of 1200 bps on all clients. Recently, pc (1) started getting
terrible throughput, say 120 kbps, rather spontaneously. I tried the
usual suspects: reset the router, reboot PC's, reinstall drivers on pc
(1), reset TCP/IP, all to no avail. All the other PC's meanwhile were
fine. Digging deeper, I did a "repair" install of Windows on (1). No
joy.

Since PC (1)'s throughput's rate was killed so suddenly I suspected
either some crazy software was installed, the internal adapter on (1)
was going south, or there was something screwed with TCP/IP. I could
not find any suspicious software on (1), so I installed (and plugged
in) the Linksys external "b" adapter in (1). It worked great: 1200
bps.

Thinking this confirmed my suspicions about the internal adapter on
(1), I bought a new external Linksys g adapter for (1). To my
amazement, not only did the throughput on (1) NOT improve with this
new adapter, installing the same adapter on PC's (2) and (3) also
brought them down to pitiful throughputs.

So my conclusion is, this Linksys BEFW11S4 (802.11b) is not really
compatible with some 801.11g adapters, including some Linksys wireless
adapters.

I've read some other posts, mostly old, that poo-poo the idea of
incompatibility between b and g equipment. Any ideas here? I will
probably acquire a "g" WAP in the near future -- in part to test my
theory, and in part to satiate PC (1) who has terrible throughput at
the moment...
3 answers Last reply
More about compatibility
  1. Archived from groups: alt.internet.wireless (More info?)

    "Smartin" <not@here.ok> wrote in message
    news:2nvhr053u2n4asbfouekjdlb36ikf0pvet@4ax.com...
    > Hi wireless fans... long time listener, first time caller...
    >
    > We've enjoyed a nice wireless LAN with a Linksys BEFW11S4 (firmware v
    > 1.45z, an 802.11b router) providing a gateway to cable internet,
    > serving a few laptop PC's:
    > (1) Windows XP home, internal Broadcom 802.11g adapter
    > (2) Windows XP home, external Linksys WPC11 (802.11b) adapter
    > (3) Windows XP pro, internal LanExpress 802.11b adapter
    > (4) Windows XP home, internal 802.11g adapter
    > ... and a couple wired clients
    >
    > The router is configured for MAC address filtering, but no WEP.
    >
    > Everything was groovy for almost a year. Typical throughput was on the
    > order of 1200 bps on all clients. Recently, pc (1) started getting

    I think you meant 1200 Kbps (1.2Mbps), right? That would be an aggregate
    throughput of of 4.8 Mbps, about what you'd expect for 802.11b.

    > terrible throughput, say 120 kbps, rather spontaneously. I tried the
    > usual suspects: reset the router, reboot PC's, reinstall drivers on pc
    > (1), reset TCP/IP, all to no avail. All the other PC's meanwhile were
    > fine. Digging deeper, I did a "repair" install of Windows on (1). No
    > joy.

    If you haven't changed the configuration on the router or any of the
    clients, then something has to have changed in the operating environment -
    host hardware problems, host processor overload, some other network
    interfering, something new between the client and the router that absorbs
    the signal, etc.

    Did you check the site survey to see if any new networks are showing up? Did
    you try changing the network's center channel? Have you recently bought a
    2.4 Ghz cordless phone or some other device that uses 2.4 Ghz (like a video
    sender, for example)?

    >
    > Since PC (1)'s throughput's rate was killed so suddenly I suspected
    > either some crazy software was installed, the internal adapter on (1)
    > was going south, or there was something screwed with TCP/IP. I could
    > not find any suspicious software on (1), so I installed (and plugged
    > in) the Linksys external "b" adapter in (1). It worked great: 1200
    > bps.

    Your instinct is right, that something environmental changed.

    >
    > Thinking this confirmed my suspicions about the internal adapter on
    > (1), I bought a new external Linksys g adapter for (1). To my
    > amazement, not only did the throughput on (1) NOT improve with this
    > new adapter, installing the same adapter on PC's (2) and (3) also
    > brought them down to pitiful throughputs.
    >
    > So my conclusion is, this Linksys BEFW11S4 (802.11b) is not really
    > compatible with some 801.11g adapters, including some Linksys wireless
    > adapters.

    This conclusion is incompatible with the fact the the Broadcom G adapter
    worked fine for a year. The fact that the Linkys B adapter worked but the
    Linksys G did not proves nothing. Those two adapters probably differ in more
    ways than just B vs. G. They may have been made by different vendors (resold
    by Linksys), using different antennas, and may have different receiver
    sensitivities. It sounds to me like you have some new source of interference
    that pushed the old Broadcom card over the edge, but your old Linksys B card
    happens to be able to tolerate it.

    >
    > I've read some other posts, mostly old, that poo-poo the idea of
    > incompatibility between b and g equipment. Any ideas here? I will
    > probably acquire a "g" WAP in the near future -- in part to test my
    > theory, and in part to satiate PC (1) who has terrible throughput at
    > the moment...

    Let's define compatibility. According to the standards, it means that a G
    access point supports a mix of B and G clients, by design. It does *not*
    mean there is no performance penalty. There is always a penalty. If the B
    clients are very quiet, the G clients can operate at full G bitrates, with
    only a little throughput penalty for certain messages used to co-ordinate
    between the different client types. If the B clients generate even moderate
    traffic, all clients will be dragged down to B bitrates.

    If your access point is configured to support a B network, then *all*
    clients will connect as B clients, whether they are capable of G or not. A B
    access point cannot support or even recognize a G client. The G client
    recognizes B, and switches to that mode when associating with the access
    point.

    If you buy a G router, and host 1 goes back to full throughput, it still
    doesn't prove the theory that G is incompatible with B. It probably just
    proves that your new router has a higher transmit power, better antennas, or
    both.
  2. Archived from groups: alt.internet.wireless (More info?)

    "gary" <pleasenospam@sbcglobal.net> wrote in message
    news:Wnvud.38895$bP2.26418@newssvr12.news.prodigy.com...
    >
    > If you haven't changed the configuration on the router or any of the
    > clients, then something has to have changed in the operating environment -
    > host hardware problems, host processor overload, some other network
    > interfering, something new between the client and the router that absorbs
    > the signal, etc.
    >
    I would also reset the router; not just reboot, but clear out the settings
    and start over. The wireless router software can get messed up it seems
    from what I have read. And I have had an access point go bad on me, such
    that the throughput dropped considerably, though that does not necessarily
    explain this situation.
  3. Archived from groups: alt.internet.wireless (More info?)

    On Sat, 11 Dec 2004 05:15:34 GMT, "gary" <pleasenospam@sbcglobal.net>
    wrote:

    >"Smartin" <not@here.ok> wrote in message
    >news:2nvhr053u2n4asbfouekjdlb36ikf0pvet@4ax.com...
    >> Hi wireless fans... long time listener, first time caller...
    >>
    >> We've enjoyed a nice wireless LAN with a Linksys BEFW11S4 (firmware v
    >> 1.45z, an 802.11b router) providing a gateway to cable internet,
    >> serving a few laptop PC's:
    >> (1) Windows XP home, internal Broadcom 802.11g adapter
    >> (2) Windows XP home, external Linksys WPC11 (802.11b) adapter
    >> (3) Windows XP pro, internal LanExpress 802.11b adapter
    >> (4) Windows XP home, internal 802.11g adapter
    >> ... and a couple wired clients
    >>
    >> The router is configured for MAC address filtering, but no WEP.
    >>
    >> Everything was groovy for almost a year. Typical throughput was on the
    >> order of 1200 bps on all clients. Recently, pc (1) started getting
    >
    >I think you meant 1200 Kbps (1.2Mbps), right? That would be an aggregate
    >throughput of of 4.8 Mbps, about what you'd expect for 802.11b.

    Well duh me... what's a factor of 1000 between friends?

    >> terrible throughput, say 120 kbps, rather spontaneously. I tried the
    >> usual suspects: reset the router, reboot PC's, reinstall drivers on pc
    >> (1), reset TCP/IP, all to no avail. All the other PC's meanwhile were
    >> fine. Digging deeper, I did a "repair" install of Windows on (1). No
    >> joy.
    >
    >If you haven't changed the configuration on the router or any of the
    >clients, then something has to have changed in the operating environment -
    >host hardware problems, host processor overload, some other network
    >interfering, something new between the client and the router that absorbs
    >the signal, etc.
    >
    >Did you check the site survey to see if any new networks are showing up? Did
    >you try changing the network's center channel? Have you recently bought a
    >2.4 Ghz cordless phone or some other device that uses 2.4 Ghz (like a video
    >sender, for example)?

    There is no new equipment and no changes on my network. Nothing new as
    far as electronics in the house (unless you count Christmas tree
    lights? ... but those were installed after the problems began (^: )

    Interesting question about new networks... PC(1) does not see any new
    networks. However PC(4) routinely sees 2 or 3 foreign networks, and
    occasionally prefers to connect to one of them even though my AP is
    certainly the closest. Both (1) and (4) have internal G adapters, and
    my AP is strictly B so I think I can understand (4)'s preference,
    however (1) does not see the same opportunities.

    The other thing I neglected to mention about (1) is its curious ping
    results. Even when (1)'s throughput was normal, a typical ping (say,
    to www.google.com) would show 25-50% dropouts. The successful packets
    had times consistent with other machines on this network. Same is true
    pinging any machine on the LAN. Pinging the loopback address is always
    100% successful. Now that the throughout is poor, pings have not
    really changed: still 25-50% dropouts pinging any other host, and
    still normal timing on returned packets. This profile is also observed
    when (1) uses the external B adapter. Since the ping behavior does not
    vary with connection quality or method, it seems doubtful the high
    dropout rate and poor throughput share the same cause, but it seems
    unusual enough to warrant a mention.

    >> Since PC (1)'s throughput's rate was killed so suddenly I suspected
    >> either some crazy software was installed, the internal adapter on (1)
    >> was going south, or there was something screwed with TCP/IP. I could
    >> not find any suspicious software on (1), so I installed (and plugged
    >> in) the Linksys external "b" adapter in (1). It worked great: 1200
    >> bps.
    >
    >Your instinct is right, that something environmental changed.
    >
    >>
    >> Thinking this confirmed my suspicions about the internal adapter on
    >> (1), I bought a new external Linksys g adapter for (1). To my
    >> amazement, not only did the throughput on (1) NOT improve with this
    >> new adapter, installing the same adapter on PC's (2) and (3) also
    >> brought them down to pitiful throughputs.
    >>
    >> So my conclusion is, this Linksys BEFW11S4 (802.11b) is not really
    >> compatible with some 801.11g adapters, including some Linksys wireless
    >> adapters.
    >
    >This conclusion is incompatible with the fact the the Broadcom G adapter
    >worked fine for a year. The fact that the Linkys B adapter worked but the
    >Linksys G did not proves nothing. Those two adapters probably differ in more
    >ways than just B vs. G. They may have been made by different vendors (resold
    >by Linksys), using different antennas, and may have different receiver
    >sensitivities. It sounds to me like you have some new source of interference
    >that pushed the old Broadcom card over the edge, but your old Linksys B card
    >happens to be able to tolerate it.
    >
    >>
    >> I've read some other posts, mostly old, that poo-poo the idea of
    >> incompatibility between b and g equipment. Any ideas here? I will
    >> probably acquire a "g" WAP in the near future -- in part to test my
    >> theory, and in part to satiate PC (1) who has terrible throughput at
    >> the moment...
    >
    >Let's define compatibility. According to the standards, it means that a G
    >access point supports a mix of B and G clients, by design. It does *not*
    >mean there is no performance penalty. There is always a penalty. If the B
    >clients are very quiet, the G clients can operate at full G bitrates, with
    >only a little throughput penalty for certain messages used to co-ordinate
    >between the different client types. If the B clients generate even moderate
    >traffic, all clients will be dragged down to B bitrates.
    >
    >If your access point is configured to support a B network, then *all*
    >clients will connect as B clients, whether they are capable of G or not. A B
    >access point cannot support or even recognize a G client. The G client
    >recognizes B, and switches to that mode when associating with the access
    >point.
    >
    >If you buy a G router, and host 1 goes back to full throughput, it still
    >doesn't prove the theory that G is incompatible with B. It probably just
    >proves that your new router has a higher transmit power, better antennas, or
    >both.

    Thanks for your input.
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