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</o:shapelayout></xml><![endif]--></head><body bgcolor=white 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'>Why is asymmetrical routing bad if you have a complete mesh?<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'>-Drew<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'><o:p> </o:p></span></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"'> Diederik Schouten [mailto:dschout@high5.net] <br><b>Sent:</b> Thursday, May 31, 2012 7:00 PM<br><b>To:</b> Drew Weaver<br><b>Cc:</b> foundry-nsp@puck.nether.net<br><b>Subject:</b> Re: [f-nsp] Asymmetrical routing on ADX<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>Since the session/ip/port information does not change, I very much doubt it had anything to do with the way source-nat replies are coming back.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I expect it had all to do with the much more logical impact of the various security features and packetprocessing/forwarding logic.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Are the replies coming back from at least the same MAC address?<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Looking at your setup I'm quite sure they are not.<o:p></o:p></p></div><div><p class=MsoNormal>MAC info is also included in the sessioncache/state-tables.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>For fast processing (as the ADX) in its core is a switch it would be most efficient to return packets belonging to a particular session to the MAC address the packets were received from...<o:p></o:p></p></div><div><p class=MsoNormal>Or for security reasons you normally would want packets from a particular session to keep coming in on the same interface from the same MAC address... as anti-spoofing solution.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>There is a not-so well documented command to set this to IP based rather than MAC based if I remember correctly.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I can't find it for the moment, but will look into it tomorrow.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I have to add that asym-routing in general is bad and should be avoided.<o:p></o:p></p></div><div><p class=MsoNormal>Why is this happening in your network? And is there a way to avoid it?<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Greetings,<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal> Diederik<o:p></o:p></p></div><div><p class=MsoNormal><br>Sent from my iPhone<o:p></o:p></p></div><div><p class=MsoNormal style='margin-bottom:12.0pt'><br>On 31 mei 2012, at 23:24, Drew Weaver <<a href="mailto:drew.weaver@thenap.com">drew.weaver@thenap.com</a>> wrote:<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><p class=MsoNormal>Hi,<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I have recently experienced a problem where performance to a VIP is terrible when the ADX is uplinked to two separate routers running VRRP. TAC suggested that it is because source-nat replies were coming back on a different physical interface than the requests went out on.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>In my config I have ports 1 and 3 assigned to the same VLAN with a virtual ethernet attached. If both of the physical ports are assigned to the same VLAN/VE then why would the ADX care which VLAN members the replies return on? That seems to defeat the purpose of having virtual ethernet or L3 VLAN style functionality.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>There has to be a work around for this, does anyone know what it is?<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><br><br><br><br><br>Sent from my Samsung Galaxy Tab <o:p></o:p></p></div></div></blockquote><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><p class=MsoNormal>_______________________________________________<br>foundry-nsp mailing list<br><a href="mailto:foundry-nsp@puck.nether.net">foundry-nsp@puck.nether.net</a><br><a href="http://puck.nether.net/mailman/listinfo/foundry-nsp">http://puck.nether.net/mailman/listinfo/foundry-nsp</a><o:p></o:p></p></div></blockquote></div></body></html>