In article <Awtrd.4578$(E-Mail Removed)>,
Mike <(E-Mail Removed)> wrote:
:the connections says 11 Mbps, the router is only 25 feet away down some
:stairs, all the operating systems on the network use XP. When other people
:are on the network I can barely surf. Will switching channels on the router
:fix the problem? I live in a condominium community so are the neighbors
:causing interferrence?
Possibly, but we don't have sufficient information.
Is the wireless router locked down with an encryption key that only you
know? If not, then others may be (deliberately or accidently) associating
with the wireless router, and you may be encountering some collision
avoidance measures... and of course the others might be using up all
the bandwidth.
But before getting into that, I would strongly recommend that you
check the duplex settings of the wireless router to the RoadRunner
broadband modem. The speeds you are seeing very much suggest that
you have a mismatch, such as if one of the devices is set to autonegotiate
and the other one is set at a fixed speed and duplex. It is vital that
both devices be set the same way -- either both set to autonegotiate, or
both set to a fixed speed and duplex.
If the wireless router believes the link is full duplex then the
wireless router will believe that it is safe to set your TCP 'ACK'
packets back up the wire at the same time the broadband modem is
sending data down the wire [full duplex == can send and receive at
the same time.] If, though, the broadband modem is either set to
half duplex or set to autonegotiate when the wireless router is set
not to negotiate, then the broadband modem is not going to expect those
returning ACKs, and is going to treat them as "late collisions" and
abort sending the packet. Normal TCP sends ACKs every second packet,
but your performance ends up much worse than that: the other end
isn't going to receive the ACK and so it is going to resend not just
the packet that got the late collission but also the two packets prior
that the ACK would have covered; that's 3 packets, and that's going
to set off another ACK that's going to lead to another late collission...
There are also some timeouts involved before retransmissions start,
and those timeouts can be as long as 1/2 second each (with 1/5 second
fairly common.)
When you have a duplex mismatch, the wonder is not that the transmission
ends up so slow: the wonder is that you get any data through at all.
--
Oh, to be a Blobel!
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