# FreeBSD 8.1 - Wrong Link-Local Address when DAD occurs



## lifanwu0925 (Feb 23, 2011)

Dear all:

I have installed FreeBSD 8.1 on HP DL-360G5.

I want to verify the DAD function in the IPv6 Ready Logo test, 1.2 Part D: Duplicate Address Detection ipv6 interface.

Here is my one of network interfaces.


```
No-1
# ifconfig bce1  bce1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500               
options=c01bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,VLAN_HWTSO,LINKSTATE>           ether 00:1f:29:cc:5a:64          
inet6 fe80::21f:29ff:fecc:5a64%bce1 prefixlen 64 scopeid 0x6          
nd6 options=3<PERFORMNUD,ACCEPT_RTADV>          
media: Ethernet autoselect (100baseTX <half-duplex>)          
status: active
```

I used the host "No-2" to add the Link-Local address with the same ipv6 Link-local address as No-1.

When No-1 use "*ifconfig bce1 up*", it will got the DAD NA from NO-2.

However, I use the command "*dmesg*", and FreeBSD 8.1 recognize as follows:


```
nd6_na_input: duplicate IP6 address fe80:6::21f:29ff:fecc:5a64 (It should be fe80::21f:29ff:fecc:5a64)
```

FreeBSD thinks Link-Local address in the DAD NA doesn't match its Link-Local address.

So it won't disable ipv6 function on bce1.

Does anybody meet this problem?


----------



## lifanwu0925 (Mar 4, 2011)

Dear all:

I found that when put 
	
	



```
net.inet6.ip6.dad_count=2
```
 in /etc/sysctl.conf when a host has the same Link-Local address with FreeBSD and then FreeBSD enables its interface later, it will disable IP operation.

However, if the value 
	
	



```
net.inet6.ip6.dad_count=1
```
 the FreeBSD won't disable IP operation.

Does anybody meet this problem?

I appreciate your help.


----------

