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<div class="moz-cite-prefix">On 10/01/2014 03:27 PM, Chuck Anderson
via Outages wrote:<br>
</div>
<blockquote class=" cite"
id="mid_20141001152700_GG16762_angus_ind_WPI_EDU"
cite="mid:20141001152700.GG16762@angus.ind.WPI.EDU" type="cite">Interesting.
Does the 1480 MTU setting from RA show up on your
interface configuration, or in a routing table entry?</blockquote>
<br>
No, and no (found no easy way to check).<br>
<br>
<blockquote class=" cite"
id="mid_20141001152700_GG16762_angus_ind_WPI_EDU"
cite="mid:20141001152700.GG16762@angus.ind.WPI.EDU" type="cite">Is
your TCP
connection to <a class="moz-txt-link-abbreviated" href="http://www.juniper.net">www.juniper.net</a> using an MSS of 1220? If so, then of
course you wouldn't see the issue.<br>
</blockquote>
<br>
Found no easy way to check.<br>
<br>
However, if I were in your place, I would be watching for ICMPv6
packets coming in <u>your</u> direction (including from your edge
router) while capturing the TCP connection startup (namely, watching
for PMTU to be determined).<br>
<br>
I am running Ubiquiti (EdgeOS), and it uses radvd. The following is
what I see in /etc/radvd.conf:<br>
<pre>interface eth2 {
# This section was automatically generated by the Vyatta
# configuration sub-system. Do not edit it.
#
# Generated by root on Sun Sep 7 13:01:05 2014
#
IgnoreIfMissing on;
AdvSendAdvert on;
AdvOtherConfigFlag off;
AdvDefaultLifetime 180;
AdvLinkMTU 1480;
AdvCurHopLimit 64;
AdvReachableTime 0;
MaxRtrAdvInterval 60;
MinRtrAdvInterval 20;
AdvDefaultPreference medium;
AdvRetransTimer 0;
AdvManagedFlag off;
prefix myprefix::/64 {
AdvPreferredLifetime 3600;
AdvAutonomous on;
AdvOnLink on;
AdvValidLifetime 43200;
};
RDNSS blah blah { };
};
</pre>
(The reason for those short-ish preferred and valid lifetimes is
that I am investigating unsolicited ingress traffic targeting
ephemeral (RFC 4941) addresses on my LAN.)<br>
<br>
While watching a web browser conversation with <a class="moz-txt-link-abbreviated" href="http://www.juniper.net">www.juniper.net</a>, I
see the initial SYN with MSS of 1420 and return SYN ACK with MSS
1440.<br>
<br>
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