Date: 21 Dec 2005 10:51:29 -0000
From: "PRAMENDRA  SINGH" <parma_it@rediffmail.com>
Subject: [users:00213] Problems in Tunnel Conformance Testing....
To: "users" <users@tahi.org>
Cc: "contact" <contact@tahi.org>
Message-Id: <20051221105129.28674.qmail@webmail63.rediffmail.com>
X-Mail-Count: 00213

Hi to all ,

this is Pramendra here..

I am working on TUNNEL modul=e. For testing (conformance testing for
ipv6-over-ipv4 =tunnel, RFC 289=3),I am using FREE-BSD 5.4 as Tester Node and TAHI tool (v6e=val 3.0) as =testing tool.

While testing I face some problem and I felt that this i=s due to the 
problems in script. So, I modified accordingly.please check= it whether changes made by me are correct or not and at the same time whet=er they 
are fulfilling the test conditions correctally or not??


=Here are the datils of changes made by me:

1.In fragment.seq

%ret==vRecv($IF1,5,0,0,v6overv4_echo_request_LINK1_nut2tn_1300, v6overv=4_ec=ho_request_LINK1_nut2tn_1300_DF);

/* I CHANGED UPPER LINE TO THE N=E=XT LINE */

%ret=vRecv($IF1,5,0,0,v6overv4_echo_request_LINK1_nut2tn==_1300_DF, v6overv4_echo_request_LINK1_nut2tn_1300);

CLARIFICATION: =when TN is sending a packet to NUT on link0 with packet 
length 1280,NUT =is replying on Link1 with a packet of length 1300 
with DF bit SET. But o=rigional script was recognizing it as a packet 
with length 1300 with DF =bit NOTSET. After changing the script, 
script is getting the packet corr=ectally.


2.In fragment.def

//
// ICMPv4 Packet Too Big messa=ge
//

FEM_i=cmp4_destination_unreachable (
	icmp4_packet_too_big=_LINK1_tn2nut_MTU_142=0,
	_HETHER_tn2nut,
		{
		DF=1;
		_SRC(V4=_OFFLINK_ADDRESS);
		_=DST(NUT_LINK1_V4_ADDRESS);
	},
		{
		Code==4;
		Unused=1420;
	=	payload=v4_orignal_packet_1450;/* I CHANG=ED HERE*/
             
   =            /* I CHANGED UPPER LINE TO TH=E THIS LINE */
               pa=yload=v6overv4_orignal_packet_1500;=

           }
)

       


CLARIFICATION: In the origional= script when TN is sending a "Too Big" 
message with MTU 1420 to NUT on L=ink1, it sending it with the wrong 
Source Address  and NUT was not able =to change its MTU. But, further 
in the test TN is again sending a "Too B=ig" message with MTU 1300 to NUT on Link1, and this time NUT MTU was being =changed successfully. The only difference in both packets was the payload a=nd value of the variable "unused" in the packet definition. So, I just chan=ged the payload to same one like it was in the "Too Big" message with MTU 1=300
and kept the variable's value unchanged. After making the change NUT =MTU was being changed successfully.

I gave prink statment in net/ipv4/=route.c file in ip_rt_f=rag_needed()
function and tried to find the rea=son for why NUT MTU was not being 
changed when TN is sending a "Too Big"= message with MTU 1420 to NUT 
on Link1. I find that the condition  "rth-=>rt_src  == iph->saddr"  
(line= no 1071) was not being met and so =it was not getting in the 
code and NUT MTU was not being changed. But wh=en TN is sending a "Too 
Big" message with MTU 1300 to NUT on Link1. I fi=nd that the condition 
"rth->rt_src  == iph->saddr" was being met and= so it was getting in 
the code and NUT MTU was being changed successfull=y.


Thanks and Regards
Pramendra Singh
Larsen and Toubro Infotec=h Limited, 
Bangalore –560001
Contact No : 080-25323734/5/6  Extn :30=5
	
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