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<font face="Tahoma">So we've been discussing this on Slack.<br>
<br>
It seems the packet handlers for IS-IS in FRR and how they work on
FreeBSD is not completely optimized (not an issue on Linux).<br>
<br>
FRR-based IS-IS on FreeBSD is sending PSNP's that are 6,020 bytes
large. However, FreeBSD's BPF (Berkeley Packet Filter) has a
packet data limit of 4,096 bytes. This is what is causing the
error.<br>
<br>
While it is possible to set the IIH MTU in FRR with the "lsp-mtu"
command, there is not way to set the PSNP MTU.<br>
<br>
In short, IS-IS on FRR does not understand that there is an MTU
limit for PSNP's on FreeBSD.<br>
<br>
I'm working with the IS-IS FRR team, but as of now, no idea on
if/when there will be a fix for this.<br>
<br>
While routes are being successfully exchanged between FRR and
Cisco IOS XE for IS-IS, this is a show-stopper! So for the moment,
I cannot recommend anyone runs IS-IS on FRR in production.<br>
<br>
As it stands, it appears that this is the only thing standing in
the way of a successful deployment, as far as simple Anycast
services go.<br>
<br>
Will keep you all posted as this develops.<br>
<br>
Mark.<br>
</font><br>
<div class="moz-cite-prefix">On 18/Apr/20 16:34, Tony Li wrote:<br>
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<div dir="ltr">No, IIH’s are padded, hot PSNP’s.</div>
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<div dir="ltr">Tony</div>
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<blockquote type="cite">On Apr 18, 2020, at 3:08 AM,
<a class="moz-txt-link-abbreviated" href="mailto:adamv0025@netconsultings.com">adamv0025@netconsultings.com</a> wrote:<br>
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<p class="MsoNormal"><span
style="mso-fareast-language:EN-US">Just shooting in the
dark, Isn’t the PSNP padded to some ISIS defined max MTU
and that somehow fails due to mismatch on em0 L2 MTU?<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="mso-fareast-language:EN-US">adam<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span
lang="EN-US"> NANOG
<a class="moz-txt-link-rfc2396E" href="mailto:nanog-bounces@nanog.org"><nanog-bounces@nanog.org></a> <b>On Behalf Of </b>Mark
Tinka<br>
<b>Sent:</b> Friday, April 17, 2020 11:05 AM<br>
<b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:nanog@nanog.org">nanog@nanog.org</a><br>
<b>Subject:</b> IS-IS Error (FRR)<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span
style="font-family:"Tahoma",sans-serif">Hi
all.<br>
<br>
I'm almost there getting IS-IS to work without issue.
I'm now faced with the following error log:<br>
<br>
2020/04/17 10:02:01 ISIS: IS-IS bpf: could not
transmit packet on em0: Input/output error<br>
2020/04/17 10:02:01 ISIS: [EC 67108865] ISIS-Snp (1):
Send L2 PSNP on em0 failed<br>
<br>
This repeats every second.<br>
<br>
Anyone know what this could be?<br>
<br>
Systems is FreeBSD-12.1-RELEASE-p3.<br>
<br>
Despite the error, IS-IS is running and routing is
good, talking to a Cisco IOS XE implementation on the
other side. So the error is throwing me off.<br>
<br>
No feedback from the Slack feed, Google doesn't say
much, and waiting to hear back from the FRR list.<br>
<br>
Mark.</span><o:p></o:p></p>
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