<html>
<head>
<style><!--
.hmmessage P
{
margin:0px;
padding:0px
}
body.hmmessage
{
font-size: 12pt;
font-family:Calibri
}
--></style></head>
<body class='hmmessage'><div dir='ltr'>I'm fan of this article:<br><br><a href="http://www.cisco.com/c/en/us/support/docs/ip/generic-routing-encapsulation-gre/25885-pmtud-ipfrag.html" target="_blank">http://www.cisco.com/c/en/us/support/docs/ip/generic-routing-encapsulation-gre/25885-pmtud-ipfrag.html</a><br><br>It talks about MSS and MTU preferred settings for GRE and GRE+IPSec.<br><br>Timothy<br><br><br><br><div>> Date: Tue, 1 Jul 2014 16:56:28 +1000<br>> From: joe@apcs.com.au<br>> To: AusNOG@lists.ausnog.net<br>> Subject: [AusNOG] GRE Tunnel MTU suggestions<br>> <br>> Hi List,<br>> <br>> Setting up a GRE tunnel for a customer and would appreciate a bit of <br>> input.<br>> <br>> I can successfully push 1500byte packets with df-bit set between the 2 <br>> endpoints (1501 fails), so it is a full mtu of 1500.<br>> <br>> I'd like to set an ip mtu on the tunnel and an ip tcp adjust-mss. <br>> Obviously I can't use 1500 as we have to account for GRE, so I'd like to <br>> know the best suggestions for an MTU, and if its worth setting the MSS <br>> at the same size as the MTU or if I should lower the MSS adjust and if <br>> so by how much?<br>> <br>> Note: IPSec is not used on top, just GRE.<br>> <br>> Thanks,<br>> Joe<br>> _______________________________________________<br>> AusNOG mailing list<br>> AusNOG@lists.ausnog.net<br>> http://lists.ausnog.net/mailman/listinfo/ausnog<br></div> </div></body>
</html>