[Dibbler] FW: DHCPv6 issue

Tomasz Mrugalski thomson at klub.com.pl
Sun Nov 12 20:47:29 CET 2006

On Sun, 12 Nov 2006 somebody known as nagarajan.balamukundan at wipro.com wrote:

>     I'm facing a problem in using my DHCPv6 cilent. The client is
> running on VxWorks platform and I've setup a Dibbler server on a Win
> 2003 machine. It's solicit messages are recognized and it goes on to
> form the Advertisement. But the packet doesn't come out in the network.
> But the response may just start coming randomly. There is no certainty
> that on a given attempt I get back the advertisement. But if I do go on
> to receive advertisement, the complete message exchange including
> REQUEST, REPLY, goes on. Please can anyone suggest what is the solution.
There are several things that you should investigate.

1. Dibbler reports that is has received packets on the ToshibaLab (which 
has interface index 4). However, your server config file instructs dibbler 
to use "Local Area Connection" interface. (I think you just sent wrong 
server config file).

2. I have no experience with Windows 2003. But in Windows XP the common 
problem is an enabled firewall. Make sure that you have firewall disabled.
Take a look at Dibbler User's Guide, FAQ section.

3. You can try 0.5.0 version, but I believe there were no changes in the 
Windows low-level sections.

4. Since you are developing your own client, you are have debugging 
experience. If you are interested, you can run dibbler server in the 
debugger and set a breakpoint in sock_send() in 

5. If you still can't get dibbler working, I can compile a dibbler-server 
with additional debugging messages just before executing sendto() Windows 
API call, which actually sends packet.

6. After investigating the source code, I've found that dibbler might not 
log low level error message to the log file, but just print it on the 
console. So if you are running dibbler as a service, stop it, then run it 
from command-line (start -> execute... -> cmd, then type cd c:\dibbler, 
then dibbler-server run). It is possible that dibbler will print some 
additional mesages on the console. Yes, that is ugly and needs to be 
fixed. I'll improve that behavior as soon as I get some free time.

7. Dibbler is much more tested on Linux. If you don't care about server 
platform, get any Linux distribution and install dibbler on it.

Of course the last advice should be threated as the last resort, 
because it works around the problem and does not solve it.

Also note the you are using dibbler 0.4.1, which does not support prefix 
delegation, therefore it complains about option 25. Latest CVS version 
supports PD options. You can download it from CVS if you are interested in 

> As can be seen above, the Server logs suggest that the Advertisement is
> being sent, but the corresponding packets cannot be captured on
> Ethereal, and so the client goes on retransmitting the solicit.

Hope that helps,

Tomasz Mrugalski,              | "We all know Linux is great...it does    |
thomson(at)klub(dot)com(dot)pl |  infinite loops in 5 seconds."           |
                                |                           Linus Torvalds |

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