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Message-Id: <200103270313.MAA06348@moon.trad.pfu.co.jp>
To: FreeBSD-net-jp@jp.freebsd.org
In-reply-to: Your message of "Tue, 27 Mar 2001 11:38:06 JST."
             <87bsqox7g1.wl@nabechan.org> 
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Date: Tue, 27 Mar 2001 12:13:22 +0900
From: SAKUMA takayuki <takayuki@network.trad.pfu.co.jp>
Reply-To: FreeBSD-net-jp@jp.freebsd.org
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X-Distribute: distribute version 2.1 (Alpha) patchlevel 24e+000315
X-Sequence: FreeBSD-net-jp 3044
Subject: [FreeBSD-net-jp 3044] Re: about a PPPoE(ADSL)+nat problem 
Errors-To: owner-FreeBSD-net-jp@jp.freebsd.org
Sender: owner-FreeBSD-net-jp@jp.freebsd.org
X-Originator: takayuki@network.trad.pfu.co.jp

$B:45W4V!w#P#F#U$G$9!%(B

FreeBSD$B$G2r7h$7$h$&$H;W$&$J$i!$(Btcpmssd$B$r;H$&$N$,$h$$$i$7$$$G$9!%(B
$B@hF|(Bfreebsd-users-jp$B$G$bN.$l$F$^$7$?$,!%(B

# $B$I$&;H$&$+$O$o$+$j$^$;$s!%(Bman$B$J$I$GD4$Y$F$/$@$5$$$M!%(B


$B>\:Y$K=q$/$H$a$A$c$/$A$cD9$/$J$C$F$7$^$&$N$G$9$,!%!%!%!%(B

>> DF $B%S%C%H$,N)$C$F$$$k%Q%1%C%H$rGK4~$9$k$H$-$O(B icmp unreach needfrag $B$,JV$C(B
>> $B$F$/$k$O$:$J$s$G$9$,!"$=$l$,$I$3$+$GGK4~$5$l$F$$$k$N$+$J!#(B
>> $B$3$l$,$A$c$s$HFO$+$J$$$N$,860x$@$H;W$$$^$9$,!"$J$K$+?4JU$j$O$"$j$^$;$s$+!)(B
>> icmp $B$rA4ItDL$5$J$$%U%#%k%?(B, tcp, udp $B$7$+DL$i$J$$%U%#%k%?$H$+!"(Bicmp $B$r(B
>> $BDL$5$J$$(B nat $B$H$+(B...

$B$3$l$rJV$9%k!<%?$O!$%f!<%6B&$8$c$J$/$F(BISP$BB&$G$7$g$&!%(B
$B%f!<%6B&$NLdBj$8$c$J$$$H;W$$$^$9!%(B


member.nifty.ne.jp$B$+$i$N%Q%1%C%H$rH4?h$9$k$H!$:G8e$O(B

	06:10:13.907030 member.nifty.ne.jp.http > tp535.marina.home.2594:
				P 1:228(227) ack 327 win 8760 (DF)
	06:10:14.166130 member.nifty.ne.jp.http > tp535.marina.home.2594:
				F 1688:2481(793) ack 327 win 8760 (DF)

$B$C$F$J$k$N$G$9$,!$(B

	06:10:14.166130 member.nifty.ne.jp.http > tp535.marina.home.2594:
				. 228:1688(1460) ack 327 win 8760 (DF)

$B$C$F%Q%1%C%H$,$9$C$+$jH4$1Mn$A$F$k$N$,;_$k860x!%8e$NOC$N$?$a$K8@$C$F$*$/$H!$(B
$B$3$N(BIP$B%Q%1%C%H$NA4D9$O(B1500byte(IPheader(20)+TCPheader(20)+TCPdata(1460))$B!%(B


$B$J$<$3$l$,Mn$A$k$+!)$H$$$&$H!$(BPPPoE($B$*$h$SCO0h(BIP$BLV(B)$B$N6h4V$N(BMTU$B!$$D$^$j(B

	win98 --> ppp-nat(PPPoE) --> ISP$B$N(BAP --> internet --> member.nifty.ne.jp
			<-------------->
			 ADSL+$BCO0h(BIP$BLV(B
			   $B$3$3$N(BMTU

$B$,(B1454$B$7$+$J$$$N$G$9$,!$(Bmember.nifty.ne.jp$B$O%U%i%0%a%s%H6X;_(Bbit(DF)$B$r(B
$BN)$F$F(B1500byte$B$N%Q%1%C%H$rAw$C$F$/$k!%$H$9$k$H!$(BISP$B$N(BAP$B$K0LCV$9$k%k!<%?$O(B
$B!V%U%i%0%a%s%H$@$a$J$i!$$=$s$J$G$+$$$NAw$l$J$$$h!W$H(Bmember.nifty.ne.jp$B$K(B
ICMP$B$G(BPacket too big message$B$H$$$&$b$N$rJV$7$F!$!V%Q%1%C%HD9$r(B1454$B0J2<$K(B
$B$7$F$M!W$HDLCN$7$^$9!%(B

$B$b$7!$$3$l$,@5$7$/F0$$$F$$$k$J$i!$$=$N%a%C%;!<%8$r<u$1<h$C$?(Bmember.nifty.ne.jp$B$O(B
$B%Q%1%C%HD9$r(B1454$B0J2<$K$7$FEj$2$F$-$^$9!%$=$l$J$i$3$N6h4V$bDL$k!%$3$N5!9=$r(B
Path MTU discovery$B$H$$$$$^$9!%(B

$B$8$c$!:#2s$O$J$<DL$i$J$$$N!)$H$$$&$H!$%5%$%H$K$h$C$F$O(BICMP$B$rA4It%U%#%k%?$G(B
$BMn$9$H$+!$$^$?$OJL$NMW0x$K$h$C$F(BPacket too big$B$,Aw?.85$N%[%9%H(B($B:#2s$O(B
member.nifty.ne.jp)$B$^$GFO$+$J$$$3$H$,$"$k$s$G$9$M!%$@$+$i(Bmember.nifty.ne.jp$B$O(B
$B!V(BAck$B$3$J$$$J$!!W$H(B1500byte$B$N(Bpacket$B$r:FAw$9$k!%$G$b!$$=$N$^$^$8$cDL$k$O$:$b$J$$!%!%(B
$B$G!$DL?.$,;_$C$A$c$&$H$$$&$o$1$G$9!%(B


$BK\Mh$N@5$7$$BP=h$H$7$F$O!$!V(Bnifty$B$K(BICMP$B$rDL$9$h$&$K$7$F$b$i$&(B($B$9$/$J$/$H$b(B
Packet too big message$B$O(B)$B!W$H$9$k$+!$!V(BDFbit$B$rN)$F$:$KAw?.$9$k$h$&$K$7$F(B
$B$b$i$&(B(DF$BN)$F$J$1$l$P(BISP$B$N(BAP$B$N%k!<%?$G%U%i%0%a%s%H$5$l$FDL$k$+$i(B)$B!W$H$$$&(B
$B$3$H$@$H;W$$$^$9!%(B

# $B!V(BPath MTU discovery$B$r$=$C$A$NET9g$G;H$($J$/$9$k$J$i!$(BDF$B$rN)$F$k$J!%(B
# DF$BN)$F$k$s$@$C$?$i(BPath MTU discovery$B$A$c$s$HF0$/$h$&$K$7$m$h!W$H$$$&$N$,(B
# $B;d$N0U8+!%(B

$B$G$bAj<j$N%5%$%HB&$,$J$K$b$7$F$/$l$J$$$s$@$C$?$i<+J,B&$G$J$s$H$+$9$k$7$+$J$$(B
$B$o$1$G!%!%!%$G!$(BTCP$B$N(BMSS option$B$r;H$C$F(B1packet$B$"$?$j$N(BTCP$B$N%G!<%?E>AwNL$r(B
$B>.$5$/$J$k$h$&$K@)8f$7$A$c$*$&$H$$$&J}K!$,$"$j$^$9!%%k!<%?$r$7$F$$$k(BFreeBSD$B$G(B
$B$=$l$r$d$k$J$i(Btcpmssd$B$,$=$l$r$d$C$F$/$l$k$i$7$$$H$$$&$o$1$G$9!%(B

telnet$B$G7R$$$@;~$K%G!<%?$,Mh$?$H$$$&$N$O!$$3$l$O(BFreeBSD$B$+$i$d$C$?$N$G$O(B
$B$J$$$+$H;W$&$N$G$9$1$I!$(B

	06:08:50.393627 PPP.xxxxx.dti.ne.jp.1170 > member.nifty.ne.jp.http: 
				S 2884071975:2884071975(0) win 16384 <mss 1414> (DF) [tos 0x10]
								     ~~~~~~~~~~

$B$3$3$NCM$,0c$&$o$1$G$9$M!%(B1packet$B$"$?$j(B1414byte$B$K$7$F$M$H8@$C$F$k$N$G(B
$B$3$N(BTCPsession$B$G$O:GBg$G$b(BIPheader(20)+TCPheader(20)+1414=1454$B$^$G$N(B
packet$B$7$+Mh$J$/$J$k!%$3$l$J$i(BPath MTU discovery$B$,F0$+$J$/$F$bDL?.$,(B
$B$G$-$k$N$GLdBj$H$O$J$i$J$$!%(B

$B$?$@!$$3$l$r=P$7$?(BFreeBSD$B$O!V$=$l$r=P$9@h$N(BIF$B$N(BMTU$B$,(B1454$B$J$s$@!W$HCN$C$F(B
$B$$$k$+$i:G=i$+$i(Bmss$B$r(B1414$B$H$7$?$o$1$G!$$=$N(BFreeBSD$B$+$i(BEthernet(MTU=1500)$B$r(B
$B;H$C$F7R$,$C$F$$$k(BWin$B$+$i$O$=$s$J$N8+$($^$;$s!%<+J,$,=P$=$&$H$9$k(BIF$B$N(BMTU$B$O(B
1500$B$@$H$7$+8+$($J$$!%$@$+$i(Bmss=1460$B$H$7$F(BWin$B$O=P$9!%(B

Win$B$N%l%8%9%H%j$r$$$8$C$F(BMTU$B$rJQ$($k$H$$$&5;$b$I$3$+$G8+$?$3$H$,$"$j$^$9!%(B
$B$3$l$b$R$H$D$NJ}K!$G$9$1$I!$$b$&$R$H$D$O!V%k!<%?$rDL$k(Bpacket$B$NCf?H$r(B
$B=q$-49$($A$c$(!W$H$$$&J}K!!%$3$l$r$9$k$N$,(Btcpmssd$B$H$$$&$o$1$G$7$g$&!%(B

tcpmssd$B$N(Bman page$B$K$b!$$3$N$X$s$N$3$H$,=q$$$F$"$j$^$9!%(B

------
  $B:45W4V(B $B7IG7(B ( Sakuma Takayuki ) 
    ($B3t(B)$B#P#F#U(B $B%M%C%H%o!<%/;v6HIt(B $BBhFs3+H/It(B $B#N#E#T4pHW%W%m%8%'%/%H(B
    Internet : takayuki@pfu.co.jp
    Nifty    : LDE03272(office) HQC03001(home)
