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Date: Thu, 11 Apr 2002 23:31:30 +0900
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From: JINMEI Tatuya / =?ISO-2022-JP?B?GyRCP0BMQEMjOkgbKEI=?=
 <jinmei@isl.rdc.toshiba.co.jp>
To: IPv6-jp@jp.FreeBSD.org
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In-Reply-To: <200204110834.RAA14868@mosel.vrl.mei.co.jp>
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Subject: [IPv6-jp 1036] Re: Path MTU discovery
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$B$9$Y$F$N(BBSD$B$K6&DL$9$kLdBj$N$h$&$G$9$N$G!">!<j$J$,$i(Busers@jp.ipv6.org$B$K(B
cc$B$5$;$F$$$?$@$-$^$7$?!#(B

>>>>> On Thu, 11 Apr 2002 17:34:29 +0900 (JST), 
>>>>> Mitani Hiroshi <hmitani@vrl.mei.co.jp> said:

> 1)MTU $B$r(B 1500-->1400-->1500 $B$HJQ2=$5$;$?>l9g(B

> $B%k!<%?$N#2Kg(B(em0, em1)$B$N(B MTU $B$r(B ifconfig $B$G(B 1500-->1400-->1500 $B$H(B
> $B@_Dj$7$F!"FC$KLdBjL5$/F0$-$^$9!#(B

> 2)MTU $B$r(B 1500-->800-->1500 $B$HJQ2=$5$;$?>l9g(B

> MTU $B$,(B 800 $B$N>uBV$G$O!"(Bv6 $B$ODL$i$J$$$N$G$9$,!"(Bv4 $B$N%k!<%?$H$7$F$O(B
> $BF0$$$F$$$^$9!#$o$+$i$J$$$N$O!"(BMTU $B$r:F$S(B 1500 $B$KLa$7$?$H$-$G$9!#(B
> $B$3$N;~!"(Bping6 -s 1400 $B$ODL$j$^$9!#$,!"%5%$%:$,(B 1400 $B$N(B UDP $B%Q%1%C%H(B
> $B$O!"%k!<%?$rDL2a$G$-$^$;$s!#$7$+$b!"2?$N(B ICMP $B$b%k!<%?$+$i%=!<%9B&(B
> $B%[%9%H$K$OJV$C$FMh$J$$$N$G$9!#(B

$B$^$:!"(BBSD(KAME)$B$O(BIPv6$BE*$J(Blink MTU$B$r(Binterface$B$N(BMTU$B$H$OFHN)$K4IM}$7$F$$(B
$B$F!"(BIPv6$BAX$N(BMTU$B4XO"$N=hM}(B($B%U%i%0%a%s%H$9$Y$-$+!"$J$I(B)$B$K$O(BIPv6$BE*$J(BMTU$B$r(B
$B;2>H$7$F$$$^$9!#(B($B$b$A$m$s!"!VFHN)$K!W$H$O$$$C$F$b!"(Binterface MTU$B$+$i$/(B
$B$k@)8B$K$OG{$i$l$^$9!#$?$H$($P!"(Binterface MTU$B$h$jBg$-$JCM$r(BIPv6$BE*(Blink
MTU$B$H$7$F$O;}$F$^$;$s!#(B)$B!V(BIPv6$BE*(BMTU$B!W$O(B"ndp -i $B%$%s%?%U%'!<%9L>(B"$B$H$9$k(B
$B$HI=<($5$l$^$9!#(B

$B$5$F!"40A4$K$OD4$Y@Z$C$F$$$^$;$s$,!"%3!<%I$rD/$a$F>/$7%F%9%H$7$F$_$?7k(B
$B2L$+$i$9$k$H!"(Binterface$B$N(BMTU$B$rBg$-$/$7$F$b(BIPv6$BE*(BMTU$B$,$=$l$KDI?o$7$J$$(B
$B$3$H$+$i$/$kLdBj$G$O$J$$$+$H;W$o$l$^$9!#(B

2)$B$G!"(Binterface MTU$B$r(B1500$B$KLa$7$?8e$G$b(BIPv6$BE*(BMTU$B$O(B800$B$N$^$^$K$J$C$F$$(B
$B$k$O$:$G$9!#$3$3$G!"(BICMP error$B%a%C%;!<%8$,(B800 byte$B$rD6$($F$7$^$&$H!"(B
$B!V(BIPv6$B$N(Bminimum link MTU(1280 bytes)$B$h$j$b>.$5$J(BMTU$B$r;}$D(Blink$B$KBP$7$F!"(B
$B$=$N(BMTU$B$rD6$($k%Q%1%C%H$r=P$=$&$H$7$F$$$k!W$HH=CG$7$F!"%+!<%M%k$O%Q%1%C(B
$B%H$r<N$F$F$7$^$$$^$9!#$G$9$+$i!"(Bnetstat -s -p ip6$B$J$I$H$9$k$H(B
	0 datagrams that can't be fragmented
$B$H$$$&%U%#!<%k%I$N%+%&%s%?$,>e$,$C$F$$$k$O$:$G$9!#(B

$B$3$N5sF0$,K>$^$7$/$J$$$N$O3N$+$G$9$,!"$G$O$I$&$"$k$Y$-$+$H$$$&$H!"$3$l(B
$B$O$J$+$J$+Fq$7$$$H$3$m$G$9!#(Binterface MTU$B$r>.$5$/$9$k$H$-$K$O!">e$G$b(B
$B?($l$?@)Ls$K$h$j(BIPv6$BE*(BMTU$B$b>.$5$/$7$J$$$H$$$1$J$$$N$G$9$,!"(Binterface
MTU$B$rBg$-$/$9$k$H$-$K$O!"0U?^E*$K>.$5$/$7$F$$$?$N$+$b$7$l$J$$(BIPv6$BE*(BMTU
$B$rC1=c$KA}$d$9$H$$$&$o$1$K$O$$$+$J$$$+$i$G$9!#(B

$B$H$j$"$($:$O!"(BIPv6$BE*(BMTU$B$r<jF0$G@_Dj$G$-$k$h$&$K$7$F!"(Binterface MTU$B$rA}(B
$B$d$7$?8e!"I,MW$J$i(BIPv6$BE*(BMTU$B$b<jF0$GA}$d$9$h$&$K$9$k!"$/$i$$$G$7$g$&$+!#(B

> $B$=$3$G65$($F$$$?$@$-$?$$$N$O!'(B

> a. MTU $B$r(B 800 $B$K@_Dj$7$?$H$-!"%k!<%?$N5sF0$O$I$&$"$k$Y$-$+(B?
> $B%k!<%F%#%s%0$G$-$J$$$K$b4X$o$i$:!"(Brtadvd $B$O1F6A$r<u$1$:$KF0$$$F$$$k(B
> $B$h$&$G$9!#$=$l$O$=$&$$$&$b$N$J$s$G$7$g$&$+(B?

$B$3$l$bFq$7$$$H$3$m$G$9$,!"(Brtadvd$B$,(BMTU$B$r(B("auto"$B$G(B)$B%"%J%&%s%9$7$F$$$k>l(B
$B9g$K$O!"%+!<%M%kFb$N(BMTU$B$NJQ99$K<+F0E*$KDI=>$G$-$?J}$,$h$$!"$H$$$&$3$H(B
$B$/$i$$$O8@$($k$G$7$g$&(B($B$$$^$O$=$&$O$J$C$F$J$$$O$:(B)$B!#(B

$BE>Aw<+BN$rB3$1$F$$$$$+$H$$$&$H!"(Blink MTU$B$h$j>.$5$J%Q%1%C%H$G$"$l$PE>Aw(B
$B$G$-$k$O$:$G$9$7!"$b$7$+$7$?$i(Blink layer$B$G$b$C$H8-$/%U%i%0%a%s%H$5$l$k(B
$B$+$b$7$l$J$$$N$G!"0l35$K$I$A$i$,$$$$$H$$$&$3$H$O8@$($J$$$h$&$K;W$$$^$9!#(B

> b. 1500 $B$KLa$7$?8e!"(Bping6 $B$ODL$k$,!"(Budp $B$O>C<:$9$k$N$O$J$<$+(B?
> $B$5$i$K!"$J$K$+$,(B expire $B$5$l$k$N$rBT$D!"$"$k$$$O!"@Q6KE*$K(B flush $B$9(B
> $B$l$P!"$b$H$N>uBV$KLa$k$N$G$7$g$&$+(B?

$B$3$l$O>e5-$G@bL@$7$?DL$j$G$9!#8=>u$G$O!"$b$H$KLa$9J}K!$O(B
(create/destroy$B$G$-$k(Binterface$B$N>l9g$r=|$-(B)reboot$B0J30$J$$$H;W$$$^$9!#(B

				$B?@L@(B $BC#:H(B (jinmei@isl.rdc.toshiba.co.jp)
				$B3t<02q<R(B $BEl<G(B  $B8&5f3+H/%;%s%?!<(B
				$BDL?.%W%i%C%H%[!<%`%i%\%i%H%j!<(B
