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To: FreeBSD-tech-jp@jp.freebsd.org
Date: Thu, 05 Nov 98 11:46:49 +0900
From: Yoshinori Morofuji <morofuji@qncos.nec.co.jp>
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Subject: [FreeBSD-tech-jp 1888] [Q] CRC and Checksum
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$B=tF#!w#N#E#CDL?.%7%9%F%`6e=#(B $B$H?=$7$^$9!#(B
$B0JA0!"%A%'%C%/%5%`$N7W;;$K$D$$$F<ALd$7$?$b$N$G$9!#(B

itojun$B$5$s(B> >$B$^$?!"8=>u$N7W;;J}K!$G%A%'%C%/%5%`7W;;$r9T$&$H!"0J2<$NFs$D$N%G!<%?(B(IP$B%X%C(B
itojun$B$5$s(B> >$B%@(B)$B$G$O!"F1$8%A%'%C%/%5%`CM$H$J$j$^$9!#(B
itojun$B$5$s(B> >data1 : 4500002c  00040000  1e06c5fc  c31e0664  c31e4a2b
itojun$B$5$s(B> >data2 : 4500002c  0004ffff  1e06c5fc  c31e0664  c31e4a2b
itojun$B$5$s(B> >$B$D$^$j!"%M%C%H%o!<%/>e$G!"(B"0000"$B$H$$$&%G!<%?$,(B"ffff"$B$K2=$1$F$7$^$C$?>l9g$O!"(B
itojun$B$5$s(B> >$B%A%'%C%/%5%`$K0z$C3]$+$i$:$K%"%W%j%1!<%7%g%s$^$G>e$,$C$F$7$^$&$H8@$&;v$K$J(B
itojun$B$5$s(B> >$B$j$^$9!#(B
itojun$B$5$s(B> >$B$3$l$C$F!"%A%'%C%/%5%`$N%P%0!)(B
itojun$B$5$s(B> 
itojun$B$5$s(B> 	$B$=$&$$$&$b$N$G$4$6$$$^$9!#(B
itojun$B$5$s(B> 	see tcp/ip illustrated vol.II p.234

$B$+$o$$$5$s(B> $B$b(B>$B=tF#!w#N#E#CDL?.%7%9%F%`(B $B$H?=$7$^$9!#(B
$B$+$o$$$5$s(B> 
$B$+$o$$$5$s(B> $B$b(B>$B$D$^$j!"%M%C%H%o!<%/>e$G!"(B"0000"$B$H$$$&%G!<%?$,(B"ffff"$B$K2=$1$F$7$^$C$?>l9g$O!"(B
$B$+$o$$$5$s(B> $B$b(B>$B%A%'%C%/%5%`$K0z$C3]$+$i$:$K%"%W%j%1!<%7%g%s$^$G>e$,$C$F$7$^$&$H8@$&;v$K$J(B
$B$+$o$$$5$s(B> $B$b(B>$B$j$^$9!#(B
$B$+$o$$$5$s(B> network $B>e$N(B Ether packet $B$O!"(BCRC$B$G!"(Bcheck $B$5$l$F$k$+$i!"$h$$$N$G$O!)(B
$B$+$o$$$5$s(B> $B!t$=$&$$$&$3$H$G$O$J$$!)(B

$B$H$N2sEz$rD:$-$^$7$?!#(B
$BJ,$+$C$?MM$J!"J,$+$i$J$$MM$J(B...

Ether packet $B$O!"(BCRC $B$G%A%'%C%/$5$l$F$$$k$N$G!"(BTCP/IP$B$N%A%'%C%/%5%`$G$O0z$C(B
$B3]$+$k$3$H$OL5$$$H9M$($F$bNI$$$N$G$7$g$&$+!)(B

TCP/IP$B%A%'%C%/%5%`$NLr3d(B$B$,!"NI$/J,$+$i$J$/$J$j$^$7$?(B...


$B"v(B---------------------------------------------------------------$B"v(B
  $B#N#E#CDL?.%7%9%F%`6e=#(B   $BBh0l5;=QIt(B   $B=tF#(B $B5AB'(B
			e-mail: morofuji@qncos.nec.co.jp
$B"v(B---------------------------------------------------------------$B"v(B
