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===Designated router election=== The DR is elected based on the following default criteria: * If the priority setting on an OSPF router is set to 0, that means it can NEVER become a DR or BDR. * If no DR exists on the network, routes will wait until ''Wait Timer'' runs out. * When a DR fails and the BDR takes over, there is another election to see who becomes the replacement BDR. * The router sending the Hello packets with the highest priority wins the election. * If two or more routers tie with the highest priority setting, the router sending the Hello with the highest RID (Router ID) wins. NOTE: a RID is the highest logical (loopback) IP address configured on a router, if no logical/loopback IP address is set then the router uses the highest IP address configured on its active interfaces (e.g. {{IPaddr|192.168.0.1}} would be higher than {{IPaddr|10.1.1.2}}). * Usually the router with the second-highest priority number becomes the BDR. * The priority values range between 0 β 255,<ref>{{cite web |url=http://www.cisco.com/en/US/docs/ios/iproute_ospf/command/reference/iro_cr_book.pdf |title=Cisco IOS IP Routing: OSPF Command Reference |date=April 2011 |url-status=dead |archive-url=https://web.archive.org/web/20120425041808/http://www.cisco.com/en/US/docs/ios/iproute_ospf/command/reference/iro_cr_book.pdf |archive-date=April 25, 2012 |df=mdy-all |publisher=[[Cisco Systems]]}}</ref> with a higher value increasing its chances of becoming DR or BDR. * If a higher priority OSPF router comes online after the election has taken place, it will not become DR or BDR until (at least) the DR and BDR fail. * If the current DR 'goes down' the current BDR becomes the new DR and a new election takes place to find another BDR. If the new DR then 'goes down' and the original DR is now available, still previously chosen BDR will become DR.
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