<html><head><meta http-equiv="Content-Type" content="text/html charset=iso-8859-1"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">Le 8 août 2017 à 14:53, Moacir Ferreira <<a href="mailto:moacirferreira@hotmail.com" class="">moacirferreira@hotmail.com</a>> a écrit :</div><br class="Apple-interchange-newline"><div class=""><div id="divtagdefaultwrapper" dir="ltr" style="font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; font-size: 12pt; font-family: Calibri, Helvetica, sans-serif;" class=""><div style="margin-top: 0px; margin-bottom: 0px;" class="">But if you receive a 9000 MTU frame on an "input" interface that results sending it out on an interface of a 1500 MTU, then if you set DF bit the frame will just be dropped by the router.</div></div></div></blockquote><br class=""></div>The frame will be dropped and the router will send an ICMP message "packet to big" to the sender, it's network stack will received that, learn that the PMTU is lower and try with smaller fragment, see <a href="https://en.wikipedia.org/wiki/Path_MTU_Discovery" class="">https://en.wikipedia.org/wiki/Path_MTU_Discovery</a>.<div class=""><br class=""></div></body></html>