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Re: radvd gives 2 prefixes over same interface



green wrote at 2010-03-26 16:12 -0500:
> Pascal Hambourg wrote at 2010-03-26 16:05 -0500:
> > green a écrit :
> > > I have set up radvd.conf to use 
> > > the first on br0 and the second on wlan1.  But when I connect with a Debian 
> > > squeeze client over br0, the interface gets 2 global addresses, one from each 
> > > subnet.  Any ideas what the problem is?  Thanks.
> > 
> > I do not see how this can happen, unless br0 and wlan1 are connected
> > together somehow. Did you capture the RA's on both interfaces to see
> > what's going on ?
> 
> No, I will try capturing them.

I am somewhat familiar with wireshark which I am using on a client device.  I 
see icmpv6 packets from the link-scope address of the lan br0 interface to 
destination ff02::1.  Here is what I see:

src=fe80::200:24ff:fecc:xxxx(server) dest=ff02::1 proto=ICMPv6 info=RouterAdvertisement
0000   33 33 00 00 00 01 00 00 24 cc 5c b5 86 dd 60 00  33......$.\...`.
0010   00 00 00 38 3a ff fe 80 00 00 00 00 00 00 02 00  ...8:...........
0020   24 ff fe cc 5c b5 ff 02 00 00 00 00 00 00 00 00  $...\...........
0030   00 00 00 00 00 01 86 00 83 4e 40 00 00 2d 00 00  .........N@..-..
0040   00 00 00 00 00 00 03 04 40 c0 00 01 51 80 00 00  ........@...Q...
0050   38 40 00 00 00 00 20 01 04 70 c1 91 00 00 00 00  8@.... ..p......
0060   00 00 00 00 00 00 01 01 00 00 24 cc 5c b5        ..........$.\.

You are welcome to suggest a better method for capturing.


I should add also that I see the correct prefix global-scope address appear 
soon after the interface is brought up, then the incorrect prefix one later.  I 
am assuming that the solicited radvd response is correct but the unsolicited 
one is not.  Maybe I can turn off the unsolicited ones.

... I have found a "UnicastOnly" radvd.conf option, which fixes the problem.  
Any ideas?  It seems unwise to disable unsolicited advertisements.

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