On 1 Jan 2002, David Irvine wrote:
> 64k isdn=64kbits per second
>
> one byte=8bits(+2 for the tcp/ip headers)
> =6.4kbyte per second max
I suspect you mean start/stop bits here, not IP headers (which
attach to packets not to individual bytes) -- or do you have some clever
packet size computation in mind?
For example, if ISDN packets were the same size as ethernet ones
(max. 1536 bytes of which max. 1500 are data+IP-protocol headers), you
might expect to see a data bandwidth loss of about 5% because of the
headers; to get a 20% drop the data packet size would have to be about
160 bytes for an IP header of around 40 bytes...
By comparison, an RS232 serial line protocol uses 2 to 3 bits
overhead per byte transmitted, consistent with David's arithmetic above.
John.
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