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"14,880pps" for 10Mbps Ethernet : Where it comes from ?

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Yoon-Seok Kang

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Apr 9, 1996, 3:00:00 AM4/9/96
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I've read about standard 10Mbps Ethernet from a book. It reads that
standard Ethernet's limit for 64-octet frames is 14,880pps(packets per
second). How is calculated this number?

--
Yoon-Seok Kang

Kevin Oberman

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Apr 9, 1996, 3:00:00 AM4/9/96
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In article <316a1f79...@news.kornet.nm.kr>
ysk...@hansol.co.kr (Yoon-Seok Kang) writes:

64 octets of data + 8 octets of preamble + 9.6 microsecondas of IPG.
72 octets * 8 bits/octet = 576 bits
576 * .1 usec/bit = 57.6 usec
57.6 + 9.6 = 67.2 usec/packet

which allows 14,880.95238 packets/sec. I guess rounding this to 14,880
is reasonable.
--
R. Kevin Oberman
Energy Sciences Network (ESnet)
Lawrence Berkeley National Laboratory (LBNL)
EMAIL: obe...@es.net
Phone: +1 510 422-6955

1:

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Apr 9, 1996, 3:00:00 AM4/9/96
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Yoon-Seok Kang (ysk...@hansol.co.kr) wrote:
>I've read about standard 10Mbps Ethernet from a book. It reads that
>standard Ethernet's limit for 64-octet frames is 14,880pps(packets per
>second). How is calculated this number?

BW = 10 x 10^6 bits per second
Header = DA + SA + Length + FCS = 18 bytes
Data padded to 46 bytes
Overhead = Preamble (7) + SFD (1) + Interframe Gap (12) =20 bytes
Performance = ( 10 x 10^6 ) x [ ( 64 + 20 ) x 8 ] -1 = 14,880 bits per sec

--
Blaine Bauer Any opinions expressed do not necessarily
CNE, CCIE#1499 reflect the opinions of Intel Corporation
Intel Corporation
Beaverton, Oregon (USA)

Milan J. Merhar

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Apr 10, 1996, 3:00:00 AM4/10/96
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In article <316a1f79...@news.kornet.nm.kr> ysk...@hansol.co.kr (Yoon-Seok Kang) writes:
>I've read about standard 10Mbps Ethernet from a book. It reads that
>standard Ethernet's limit for 64-octet frames is 14,880pps(packets per
>second). How is calculated this number?

A minimum-sized Ethernet frame consists of 64 octets of data, or 512
bits. It is preceded by a preamble of 64 bits, and followed by an
inter-packet gap (or quiet time) of 96 bit-times.

This totals 64 + 512 + 96 = 672 bit-times to transmit a minimum-sized frame,
which at 10E6 bits/second gives 14881 frames/second.

In an actual LAN, shrinkage of both the preamble and IPG is possible,
so you might be able to create a test situation in which you could receive a
few more frames per second than this, but this is pretty much the accepted
number.

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