<P>
Hi to all ,<BR>
<BR>
this is Pramendra here..<BR>
<BR>
I am w=
orking on TUNNEL module. For testing (conformance testing for<BR>
ipv6-ov=
er-ipv4 =tunnel, RFC 2893),I am using FREE-BSD 5.4 as Tester Node and TAH=
I tool (v6e=val 3.0) as testing tool.<BR>
<BR>
While testing I face s=
ome problem and I felt that this is due to the <BR>
problems in script. S=
o, I modified accordingly.please check it whether changes made by me are co=
rrect or not and at the same time wheter they <BR>
are fulfilling the tes=
t conditions correctally or not??<BR>
<BR>
<BR>
Here are the datils o=
f changes made by me:<BR>
<BR>
1.In fragment.seq<BR>
<BR>
%ret=vR=
ecv($IF1,5,0,0,v6overv4_echo_request_LINK1_nut2tn_1300, v6overv=4_echo_re=
quest_LINK1_nut2tn_1300_DF);<BR>
<BR>
/* I CHANGED UPPER LINE TO THE N=
=EXT LINE */<BR>
<BR>
%ret=vRecv($IF1,5,0,0,v6overv4_echo_request_L=
INK1_nut2tn=_1300_DF, v6overv4_echo_request_LINK1_nut2tn_1300);<BR>
<BR=
>
CLARIFICATION: when TN is sending a packet to NUT on link0 with packet =
<BR>
length 1280,NUT is replying on Link1 with a packet of length 1300 <B=
R>
with DF bit SET. But origional script was recognizing it as a packet <=
BR>
with length 1300 with DF bit NOTSET. After changing the script, <BR>=
script is getting the packet correctally.<BR>
<BR>
<BR>
2.In fragm=
ent.def<BR>
<BR>
//<BR>
// ICMPv4 Packet Too Big message<BR>
//<BR>=
<BR>
FEM_i=cmp4_destination_unreachable (<BR>
=
icmp4_packet_too_big_LINK1_tn2nut_MTU_142=0,<BR>
_H=
ETHER_tn2nut,<BR>
{<BR>
= DF=1;<BR>
&=
nbsp; _SRC(V4_OFFLINK_ADDRESS);<BR>
&nbs=
p; _=DST(NUT_LINK1_V4_ADDRESS);<BR>
},<BR>
=
{<BR>
= Code=4;<BR>
Unused=
=1420;<BR>
= payload=v4_orig=
nal_packet_1450;/* I CHANGED HERE*/<BR>
 =
; <BR>
= /* I =
CHANGED UPPER LINE TO THE THIS LINE */<BR>
&n=
bsp; pa=yload=v6overv4_orignal_packet_1500;<BR>
<BR>=
}<BR>
)<BR>
<BR>
=
<BR>
<BR>
<BR>
CLARIFICATION: In the origional script when T=
N is sending a "Too Big" <BR>
message with MTU 1420 to NUT on L=
ink1, it sending it with the wrong <BR>
Source Address and NUT was =
not able to change its MTU. But, further <BR>
in the test TN is again sen=
ding a "Too Big" message with MTU 1300 to NUT on Link1, and this =
time NUT MTU was being changed successfully. The only difference in both pa=
ckets was the payload and value of the variable "unused" in the p=
acket definition. So, I just changed the payload to same one like it was in=
the "Too Big" message with MTU 1300<BR>
and kept the variable'=
s value unchanged. After making the change NUT MTU was being changed succes=
sfully.<BR>
<BR>
I gave prink statment in net/ipv4/route.c file in ip_r=
t_f=rag_needed()<BR>
function and tried to find the reason for why NUT =
MTU was not being <BR>
changed when TN is sending a "Too Big" m=
essage with MTU 1420 to NUT <BR>
on Link1. I find that the condition =
; "rth->rt_src == iph->saddr" <BR>
(line=
= no 1071) was not being met and so it was not getting in the <BR>
code=
and NUT MTU was not being changed. But when TN is sending a "Too <BR>=
Big" message with MTU 1300 to NUT on Link1. I find that the conditi=
on <BR>
"rth->rt_src == iph->saddr" was being m=
et and so it was getting in <BR>
the code and NUT MTU was being changed s=
uccessfully.<BR>
<BR>
<BR>
Thanks and Regards<BR>
Pramendra Singh<B=
R>
Larsen and Toubro Infotech Limited, <BR>
Bangalore –560001<BR>
C=
ontact No : 080-25323734/5/6 Extn :305<BR>
</P>
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