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<div class="moz-cite-prefix">On 14/Aug/16 12:09, Andrew Alston
wrote:<br>
<br>
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<p class="MsoNormal"><span style="font-size:11.0pt">Hi Guys,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Figured I’d
share this because someone might run into the issue I did
last night and after how long it took to figure out what was
going on, rather give people a heads up.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Under Cisco
IOS-XR 5.3.3 AND under 6.0.2 (though the documentation on
the bug explicitly states its fixed in 6.0.2, its NOT), do
not, under any circumstances, run ipv6 nd router-preference
high anywhere.</span></p>
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<br>
That's a nasty bug.<br>
<br>
I've only ran ND Router Preference in LAN scenarios, to avoid
situations where Windows Vista and Windows 7 clients automatically
enabled 6-to-4, and claimed to be the authoritative default gateway
for the LAN.<br>
<br>
The solution ended up being pointless as there was no way to fully
guarantee that the true router was the one with the highest
preference for the LAN.<br>
<br>
The ultimate solution for this is RA Guard, which I believe now has
reasonable support on decent Ethernet switches in the wild.<br>
<br>
I'm curious, though, why you'd need this on a point-to-point link,
where the remote side (CPE) may not be setup to announce ND RA's
back to the BNG.<br>
<br>
Mark.<br>
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