<div dir="ltr"><div><div><div>Not sure if this applies to all of GLBP, HSRP, VRRP, but there is a 'redundancy' option to ip helper which lets you make the dhcp-forwarder aware of the redundancy group:<br><a href="http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipapp/command/iap-cr-book/iap-i1.html#wp1413119578">http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipapp/command/iap-cr-book/iap-i1.html#wp1413119578</a><br>ip helper-address [ vrf name | global ] address { [ redundancy vrg-name ] }<br><br></div><div>So maybe something like 'ip helper-address 1.2.3.4 redundancy foo'<br></div><div><br></div>The docs are a bit sparse on this. Also, I thought I remembered something about being able to set timing somewhere so one (server or helper) would respond with some delay after the other, but I can't find it.<br><br></div>There are also ways, to dynamically provision your dhcp pools on the routers with Embedded Event Manager:<br><a href="http://www.techexams.net/forums/off-topic/95384-interesting-week-eem-applets-dhcp-ip-sla.html">http://www.techexams.net/forums/off-topic/95384-interesting-week-eem-applets-dhcp-ip-sla.html</a><br></div>Using this - you could setup a DHCP on one router, and if that router goes down the other router bootstraps a pool onto itself with EEM.<br><br><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Sep 14, 2015 at 4:16 PM, Michael Still <span dir="ltr"><<a href="mailto:stillwaxin@gmail.com" target="_blank">stillwaxin@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote"><span class="">On Mon, Sep 14, 2015 at 3:30 PM, James Sumners <span dir="ltr"><<a href="mailto:james.sumners@gmail.com" target="_blank">james.sumners@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_extra"><span><br><div class="gmail_quote">On Mon, Sep 14, 2015 at 3:09 PM, Michael Still <span dir="ltr"><<a href="mailto:stillwaxin@gmail.com" target="_blank">stillwaxin@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">This is fairly standard setup it sounds like. You have a dhcp helper config on both routers so that if one router is dead the other still passes along the dhcp requests and updates (note that the log should show it from the router interface IP and not the vrrp IP). Even though its double talk this is what you want to see on the dhcp server log to indicate that this is configured correctly.</blockquote></div><br></span>It does show from the router interface (when I look at a tcpdump of the traffic). How is it that this wouldn't be causing issues with assignment? Shouldn't multiple answers from the same DHCP host confuse the clients?</div></div></blockquote><div><br></div></span><div>The client should just use the first response received. Something to keep in mind is dhcp state synchronization across your servers if more than one server is active on a subnet at any given time. </div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><span class=""><div dir="ltr"><div class="gmail_extra"><span><br clear="all"><div><br></div>-- <br><div><div dir="ltr"><div><div dir="ltr"><div>James Sumners<br><a href="http://james.sumners.info/" target="_blank">http://james.sumners.info/</a> (technical profile)</div><div><a href="http://jrfom.com/" target="_blank">http://jrfom.com/</a> (personal site)</div><div><a href="http://haplo.bandcamp.com/" target="_blank">http://haplo.bandcamp.com/</a> (band page)</div></div></div></div></div>
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