From: Hansang Bae (hbae@xxxxxxxxxx)
Date: Thu Mar 14 2002 - 01:38:40 GMT-3
At 05:10 PM 3/13/2002 +0200, Shadi wrote:
>During my studies, I saw that we should always nail the DR Router by ip ospf
>priority, so that always that router be the DR when using Frame-relay with
>broadcast or non broadcast network type.
>What about Ethernet network why we don't nail it too?
The first router to run OSPF becomes the DR. The second one becomes BDR (in br
oadcast networks of course).
The priority comes into play if there is a tie. So if you have one with prior
ity of 1, and another with priority of 233, which one will become the DR? The
one that runs OSPF first!
Priority of zero tells the router to NEVER take part in the DR/BDR election. T
hat means that it will always be DROTHER.
In a NBMA (non fully meshed) network, you have to have the hub as the DR. So t
he spokes will always require that the priority be set to 0. Unless of course,
you can guarantee that the hub will always be the first router up.
Please keep in mind that this are little hacks that should not be used in real
networks.
In our network, we do a musical chair of "shut/no shut" to set a particular rou
ter as DR/BDR. You can't afford to set every router to priority of zero since
you then lose the flexibility of OSPF - in terms of recovering form a DR/BDR fa
ilure.
hsb
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:57:04 GMT-3