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</o:shapelayout></xml><![endif]--></head><body lang=EN-AU link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Hi guys,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Breaking with recent tradition, I thought I’d throw a network question out to the group to see if anyone has had a similar experience or can point me at some documentation other than the cisco articles on how GLBP AVFs should work.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The long and short of it is that the AVFs seem to be ignoring the weighting when deciding which connection to send outbound traffic through. I know we could drop one of the AVFs by decrementing its value below the lower threshold but that would mean removing some of the load balancing and availability options.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The setup is a GLBP group of two routers each with their own IP transit connection. One router & link has a weighting of 10 and the other router/link has a weighting of 200 with the load balancing methodology set to weighted. In theory, the router with the weighting of 200 should be taking 95 odd % of the traffic for that subnet.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The config is as follows:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l1 level1 lfo2'><![if !supportLists]><span style='font-family:Symbol'><span style='mso-list:Ignore'>·<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]>Downstream devices are configured to hit the VIP not the individual router IPs<o:p></o:p></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l1 level1 lfo2'><![if !supportLists]><span style='font-family:Symbol'><span style='mso-list:Ignore'>·<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]>The ARP tables on the router with the weighting of 200 shows that it is picking up most of the IP addresses in the subnet as expected as it is also the AVG. <o:p></o:p></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l1 level1 lfo2'><![if !supportLists]><span style='font-family:Symbol'><span style='mso-list:Ignore'>·<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]>The router with the weighting of 200 is shown as the Active AVF and the router with the weighting of 10 is in listen state (aware that a listen AVF will still forward traffic)<o:p></o:p></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l1 level1 lfo2'><![if !supportLists]><span style='font-family:Symbol'><span style='mso-list:Ignore'>·<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]>The router with the weighting of 10 has an ARP table that does not show any IPs from the subnet<o:p></o:p></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l1 level1 lfo2'><![if !supportLists]><span style='font-family:Symbol'><span style='mso-list:Ignore'>·<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]>Forwarder pre-emption is enabled<o:p></o:p></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l1 level1 lfo2'><![if !supportLists]><span style='font-family:Symbol'><span style='mso-list:Ignore'>·<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]>Bouncing the router with the weighting of 10 has the traffic redirect through the other link, but once the AVF comes up (even in listen state) it then starts transmitting traffic again.<o:p></o:p></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l1 level1 lfo2'><![if !supportLists]><span style='font-family:Symbol'><span style='mso-list:Ignore'>·<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]>Netflow reporting shows that the router with the weighting of 10 is transmitting a lot of data that should be going through the other router.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>My question is whether it’s just luck that the small amount of IP addresses allocated to the AVF with the weighting of 10 happen to have noticeable traffic or if there is some other behaviour that would explain why an AVF that should be getting virtually no traffic seems to be sending out a lot of traffic for that subnet?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The other working theory is that it’s ARP / client device affinity rather than a GLBP issue.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Happy to get thoughts by direct email rather than to the entire list.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='mso-fareast-language:EN-AU'>Thanks<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-AU'><br>Nathan<o:p></o:p></span></p></div></body></html>