From: bobdu11@cox.net
Date: Wed Aug 06 2003 - 09:00:13 GMT-3
The best and least disruptive way to force a new DR election is to change the OSPF priority of the DR to 0, this will force an election, once the new election has taken place you can set the priority back to whatever you want it to be, IE to become the BDR or a DROTHER. This procedure does not clear the routing table and force a total reconvergance of the routing table, just merely demotes the active DR to drother and forces a new election......Bobdu1
>
> From: "ccie2be" <ccie2be@nyc.rr.com>
> Date: 2003/08/06 Wed AM 06:16:37 EDT
> To: "Group Study" <ccielab@groupstudy.com>
> Subject: Clearing the OSPF process
>
> Hi,
>
> I discovered yesterday that it's necessary to clear the ospf process for a
> router to change it's router id to a new value. Aside from activating a new
> router id are there any other times when it's necessary to clear to ospf
> process for config changes to take effect?
>
> I also discovered that after a DR is elected on a multiaccess segment, and
> then the ospf process is cleared, the DR remembers it was the DR and a new DR
> is NOT elected even though another router should be the DR on that segment
> based on having a higher router-id ( priorities are all equal) when the router
> id is based on the highest loopback interface address.
>
> But, if the router id is based on a manually entered id using the router-id
> command, and then the ospf process is cleared, a new DR election does take
> place and the router with a higher router-id when manually entered becomes the
> DR.
>
> Based on these experiments performed yesterday, it seems that it's very
> difficult and time consuming and somewhat unpredictable to try to change which
> router is the DR on a segment by changing the router id's of the routers
> taking part in the election.
>
> I know that I can use ospf priority to rig the DR election but I wanted to see
> how well it is to rig the DR election based on router-id's. My conclusion is
> that it's very difficult and the results will vary based on the order in which
> the ospf processes are cleared on the router involved and whether various
> interfaces on the broadcast segment are in the up or down state.
>
> I'm wondering if anyone else has played around with this and if they have come
> to different conclusions.
>
> Thanks in advance, Raj
>
>
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