Re: Removing DAD in IPv6

[Xia Yang]

Hi,

I just find out this IFA_F_NODAD was not in the kernel used in my test
bed which is 2.6.17. So I tried to modify the code in ipv6/addrconf.c by
myself to remove the DAD:

if (!max_addresses ||
ipv6_count_addresses(in6_dev)  max_addresses)
ifp = ipv6_add_addr(in6_dev, addr, 
pinfo-prefix_len,

addr_typeIPV6_ADDR_SCOPE_MASK, 0);

if (!ifp || IS_ERR(ifp)) {
in6_dev_put(in6_dev);
return;
}
// New code 
if (!IS_ERR(ifp)) {
spin_lock_bh(ifp-lock);
ifp-flags = ~IFA_F_TENTATIVE;
spin_unlock_bh(ifp-lock);

addrconf_join_solict(ifp-idev-dev, ifp-addr);
ipv6_ifa_notify(RTM_NEWADDR, ifp);
//in6_ifa_put(ifp);
printk(New address configured.\n);
}
// --end ---
update_lft = create = 1;
ifp-cstamp = jiffies;

// addrconf_dad_start(ifp, RTF_ADDRCONF|RTF_PREFIX_RT);

However, even the new address is generated and assigned to the
interface, and I can read the address from the /proc interface, my first
few packets are eaten by the kernel. Only until after about 1 second,
then my packet can make its way out. Is kernel doing anything that
blocks the sending and receiving of packets during the time of DAD?
Thanks a lot!

Best Regards,

Xia Yang



On Mon, 2007-10-01 at 20:44 +0900, YOSHIFUJI Hideaki / 吉藤英明 wrote:
 In article [EMAIL PROTECTED] (at Mon, 01 Oct 2007 11:53:27 +0800), Xia Yang 
 [EMAIL PROTECTED] says:
 
  I would like to ask for help on how to remove or disable the DAD process
  properly, as long as the node can send, receive and forward packets
  immediately after a new IPv6 address is generated. Any pointer is
  appreciated. Thanks a lot in advance!
 
 IFA_F_NODAD address flag might help this.
 
 --yoshfuji
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Removing DAD in IPv6

[Xia Yang]

Hi all,

I am new to this list, so please forgive me if I say anything
inappropriate.

I am working on a mobility testbed based on IPv6. In order to improve
the performance, I would like to remove the DAD process during the
auto-configuration process of an IPv6 address for my testbed. 

During my experiment, I observed that when an address is configured
based on a router advertisement, the outgoing packets can be sent out
immediately. But the packets destined to local node can only be received
after some time (about 1 sec). I found the lost packets are discarded in
the kernel and never make it to the transport layer. I suspect it is
caused by the DAD process.

I would like to ask for help on how to remove or disable the DAD process
properly, as long as the node can send, receive and forward packets
immediately after a new IPv6 address is generated. Any pointer is
appreciated. Thanks a lot in advance!

Best Regards,

Xia Yang

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