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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Yes, hosts or routers-in-the-middle that don't send ICMP type 3 code 4, or which drop such a message sent by another host instead of forwarding it, do make me upset.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>But...<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>In this case we're talking about relatively narrow-band, widely-compressed RTP audio. Admittedly I rarely deal with any VoIP audio streams other than PCMU-encoded ones, so perhaps it's possible other codecs are different (though I'd be surprised...timeliness of delivery in a real-time application like this is far more important than efficiency of packing the data into as few frames as possible), but I personally have never seen an RTP frame that comes close to approaching standard Ethernet MTU. The packets are typically more like a couple hundred bytes large.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>And of course being UDP, TCP MSS doesn't enter into the picture, either.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>In short, I have a hard time believing that MTU issues are the underlying cause for many (or even any) VoIP audio delivery problems...but, as the meme goes, "change my mind"; heh.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>-- Nathan<o:p></o:p></span></p><p class=MsoNormal><a name="_MailEndCompose"><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></a></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> VoiceOps [mailto:voiceops-bounces@voiceops.org] <b>On Behalf Of </b>Pinchas Neiman via VoiceOps<br><b>Sent:</b> Sunday, March 10, 2024 7:29 AM<br><b>To:</b> Alex Balashov<br><b>Cc:</b> VoiceOps<br><b>Subject:</b> Re: [VoiceOps] One Way Audio - Frontier Comm (Los Angeles area)<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>I have (on a rural area DSL line) a desk phone registered directly on line 1, and line 2 over the VPN, whenever someone on line 1 tells me I couldn't hear you well, I am saying calling you back with another line, every time they will respond immediately Ah. Now your voice is much better.<o:p></o:p></p></div><div><p class=MsoNormal>TCP connections are also much more reliable over the VPN than direct.<o:p></o:p></p></div><div><p class=MsoNormal>I am using WG over UDP with MTU 80 bytes lower than the worst case general MTU.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I digged through my issue, and found that some hops in my long list of local hops (last mile/s) are very unreliable, and not responding when they drop (crime #1) a big packet even if DF was set (crime #2), so best for me was to have wireguard do the fragmentation on my side, as well as signal to the TCP connections to lower their MSS automatically.<o:p></o:p></p></div><div><p class=MsoNormal>In other cases a VPN will also be able to patch TCP issues related to asymmetric routing, or firewall timeouts.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>To be noted, <o:p></o:p></p></div><div><p class=MsoNormal>#1 VPN device CPU should be fast enough to do the packaging, as there is usually no hardware assistance for the VPN prepackaging.. a good gigabit router could easily become a source of latency when it involves something more than passing/nating packets between ports<o:p></o:p></p></div><div><p class=MsoNormal>#2 having a VPN without adjusting the MTU (either manually or automatically) will increase packet loss, this is the source of the myth that VPN is a overhead for VOIP<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>My understanding in networking may be flawed but this is my practical experience accumulated so far.<o:p></o:p></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>On Sat, Mar 9, 2024 at 4:00 PM Alex Balashov via VoiceOps <<a href="mailto:voiceops@voiceops.org">voiceops@voiceops.org</a>> wrote:<o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><p class=MsoNormal>No, it's true, consider me appropriately humbled. I underappreciated the nuance of this issue. I thought we were talking about something closer to the physicality of networks, not packet inspection/filtering/etc.<br><br>-- Alex<br><br>> On 9 Mar 2024, at 08:11, James Cloos <<a href="mailto:cloos@jhcloos.com" target="_blank">cloos@jhcloos.com</a>> wrote:<br>> <br>>>>>>> "AB" == Alex Balashov writes:<br>> <br>>>> I don't trust last mile networks to reliably deliver SIP calls. I usually end up putting them into VPNs, TLS, etc.<br>> <br>> AB> VPNs and TLS make last-mile networks more reliable? :-) <br>> <br>> on the vpn side, wireguard (which runs over udp) certainly does.<br>> <br>> I imagine ipsec sometimes can, too. but wg is easier.<br>> <br>> -JimC<br>> -- <br>> James Cloos <<a href="mailto:cloos@jhcloos.com" target="_blank">cloos@jhcloos.com</a>><br>> OpenPGP: <a href="https://jhcloos.com/0x997A9F17ED7DAEA6.asc" target="_blank">https://jhcloos.com/0x997A9F17ED7DAEA6.asc</a><br><br>-- <br>Alex Balashov<br>Principal Consultant<br>Evariste Systems LLC<br>Web: <a href="https://evaristesys.com" target="_blank">https://evaristesys.com</a><br>Tel: +1-706-510-6800<br><br>_______________________________________________<br>VoiceOps mailing list<br><a href="mailto:VoiceOps@voiceops.org" target="_blank">VoiceOps@voiceops.org</a><br><a href="https://puck.nether.net/mailman/listinfo/voiceops" target="_blank">https://puck.nether.net/mailman/listinfo/voiceops</a><o:p></o:p></p></blockquote></div><p class=MsoNormal><br clear=all><o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal><span class=gmailsignatureprefix>-- </span><o:p></o:p></p><div><div><div><div><div><div><div><div><div><div><div><div><div><div><div><p class=MsoNormal><b>Pinchas S. Neiman</b><o:p></o:p></p></div><div><p class=MsoNormal>Software Engineer At ESEQ Technology Corp.<o:p></o:p></p></div><div><p class=MsoNormal>845.213.1229 #2<o:p></o:p></p></div><p class=MsoNormal><img border=0 width=200 height=68 id="_x0000_i1025" src="https://ci3.googleusercontent.com/mail-sig/AIorK4z1Lx063u893FlkIV1C3aJbVPjgKnaA2Xu8q_iPdyFOnK_JX05usgghpAIwmPqB-1t-3fdaShNHoCPf7fFwa1twYZt-xjsBZheqmsCQrg"><o:p></o:p></p></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></body></html>