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</o:shapelayout></xml><![endif]--></head><body lang=EN-GB link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal><span style='mso-fareast-language:EN-US'>Interesting, so it is an MTU problem after all, I take it there’s no way to adjust the BPF (Berkeley Packet Filter) limit to let the 6020B sized PSNPs through?<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><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span lang=EN-US>From:</span></b><span lang=EN-US> Mark Tinka <mark.tinka@seacom.mu> <br><b>Sent:</b> Sunday, April 19, 2020 1:47 AM<br><b>To:</b> Tony Li <tony1athome@gmail.com>; adamv0025@netconsultings.com<br><b>Cc:</b> nanog@nanog.org<br><b>Subject:</b> Re: IS-IS Error (FRR)<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-family:"Tahoma",sans-serif'>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.</span><o:p></o:p></p><div><p class=MsoNormal>On 18/Apr/20 16:34, Tony Li wrote:<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>No, IIH’s are padded, hot PSNP’s.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Tony<o:p></o:p></p></div><div><p class=MsoNormal><br><br><o:p></o:p></p><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal style='margin-bottom:12.0pt'>On Apr 18, 2020, at 3:08 AM, <a href="mailto:adamv0025@netconsultings.com">adamv0025@netconsultings.com</a> wrote:<o:p></o:p></p></blockquote></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><p class=MsoNormal> <o:p></o:p></p><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?</span><o:p></o:p></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'> </span><o:p></o:p></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>adam</span><o:p></o:p></p><div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span lang=EN-US>From:</span></b><span lang=EN-US> NANOG <a 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 href="mailto:nanog@nanog.org">nanog@nanog.org</a><br><b>Subject:</b> IS-IS Error (FRR)</span><o:p></o:p></p></div></div><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></div></div></blockquote></blockquote><p class=MsoNormal><o:p> </o:p></p></div></div></body></html>