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Home > Archive > alt.certification.network-plus > June 2003 > Flow control?
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| pez74 2003-06-17, 12:24 pm |
| Now I know that flow control is regulated or set at the transport
layer. But I have also read that transmission rate is set at the
physical layer. How is transmission rate and flow control different
from each other? Please explain. Can anyone suggest a website or
resource that could help me really nail down the OSI model. I think I
understand it, but I just don't feel 100% confident with it yet.
Thanks. Pete
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| Techie 2003-06-17, 1:24 pm |
| for the OSI have a look here
http://www.techexams.net/technotes/.../osimodel.shtml
--
Techie
A+, Network+, MCP, MCNGP #21
"pez74" <pzelonis74@yahoo.com> wrote in message
news:cc5ce92a.0306170920.1dd1b236@posting.google.com...
> Now I know that flow control is regulated or set at the transport
> layer. But I have also read that transmission rate is set at the
> physical layer. How is transmission rate and flow control different
> from each other? Please explain. Can anyone suggest a website or
> resource that could help me really nail down the OSI model. I think I
> understand it, but I just don't feel 100% confident with it yet.
> Thanks. Pete
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| Charles M. Kozierok 2003-06-17, 2:24 pm |
| In article <cc5ce92a.0306170920.1dd1b236@posting.google.com>,
pez74 <pzelonis74@yahoo.com> wrote:
} Now I know that flow control is regulated or set at the transport
} layer. But I have also read that transmission rate is set at the
} physical layer. How is transmission rate and flow control different
} from each other? Please explain.
Your first statement is likely due to flow control being one of
the functions performed by TCP at layer 4. However, flow control
is not something layer-specific at all. It can be performed at any
layer, and in fact different types operate simultaneously at
different layers. The term simply refers to any technique whereby
the receiver of information provides feedback to the transmitter
to regulate the rate at which data is sent so the receiver is not
overwhelmed.
Flow control is also indeed a function often performed at layer 1, by
modems and other hardware devices. But there is also a flow control
feature in Ethernet at layer 2. It is even possible to incorporate flow
control into an application layer protocol (though usually they just
rely on TCP).
peace,
-*-
charles
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