On Sat, 4 Nov 2000, Chuck Larrieu wrote:
> At the risk of being anal retentive ( quiet, Rodgers :-> ) we mustn't forget
> the MTU, window size, TCP and IP headers, and ack's. I believe we have done
> a couple of threads along these lines over time. Memory probably doesn't
> serve, but I believe one can count on a 10-15% overhead cost.
>
> Also, it looks to me like the calculation below lost a couple of zeros along
> the way. My fingers and toes tell me that 230 Mbytes=1840mbits, which
> divided by 1.54 mbits per second comes out to 1195 seconds, or close to 20
> minutes.
Chuck.........nod, framing, headers, etc.......all that was left out.
You're right about the 0's, I was too tired from studying, here it is
again, hopefully correct this time:
T1
Convert to bytes
1544000 bits per second = 193000 bytes per second
193000 bytes per second / 1024 = 188.47656 kbytes per second
230000 KB / 188.47656 = 1220.3108 seconds (20.3 min)
Assuming ideal conditions (full wire speed etc)
ISDN
128000 bites per second = 16000 bytes per second
16000 bytes per second / 1024 = 15.625 kbytes per second
230000 KB / 15.625 = 14720 seconds (245min)
(~4hours)
>
> That would bring the actual file transfer speed come to about 164 seconds,
> if everything works the way it is supposed to.
no not likely. 10Mbps ethernet couldn't even transfer 230MB in 164
seconds..........think about it.
>
> Chuck
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of
> Brian
> Sent: Saturday, November 04, 2000 7:23 PM
> To: SH Wesson
> Cc: [EMAIL PROTECTED]
> Subject: Re: transfer rate
>
> On Sun, 5 Nov 2000, SH Wesson wrote:
>
> > How do we go about calculating how long it takes to calculate something
> and
> > the speed at which it is transferring. For instance, if we have a T1
> > circuit (full 1.544MB) or a 128KB link, how long will it take to transfer
> a
> > 230MB file and how fast does it transfer per second, minute, etc. I can't
> > seem to find anything that deals with calculating this sort of thing on
> > Cisco's site. Thanks.
>
> Its just basic mathmatics really. If a circuit is transmitting at
> 1.544Mbps, you can break it down as follows:
>
> Convert to bytes
> 1544000 bits per second = 193000 bytes per second
> 193000 bytes per second / 1024 = 188.47656 kbytes per second
>
> 2300kbytes per second / 188.47656 = 12.203 seconds
>
> Assuming ideal conditions (full wire speed etc)
>
> Also realistically you need to back out the framing bits and recalculate
> at 1536000 since the framing bits are unusable........but its not going to
> move that figure much. With ISDN it would go like
>
> 128000 bites per second = 16000 bytes per second
> 16000 bytes per second / 1024 = 15.625 kbytes per second
>
> 2300kbytes per second / 15.625 = 147.2 seconds
>
>
> And this jives, since a T1 is 12 times faster than a 128k isdn line.
>
> Brian
>
>
>
>
>
>
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> -----------------------------------------------
> Brian Feeny, CCNP, CCDP [EMAIL PROTECTED]
> Network Administrator
> ShreveNet Inc. (ASN 11881)
>
> _________________________________
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-----------------------------------------------
Brian Feeny, CCNP, CCDP [EMAIL PROTECTED]
Network Administrator
ShreveNet Inc. (ASN 11881)
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