From: R&S Groupstudy (rsg@synergy-networking.co.uk)
Date: Wed Aug 06 2003 - 08:02:43 GMT-3
Hi,
I can't think of a another configuration change that requires you to clear
ip ospf process.
In OSPF the DR on a lan segment is always the 1st ospf device to be powered
up and I'm afraid the DR election only happens when the current DR dies.
When this happens it'll be the higher routerID, or if the priority is
manually set on the interface. It is therefore difficult to predicty which
router will be the DR. It doesn't really matter anymore because routers are
powerful to run dykstra with big lsa topologies. If a router isn;t powerful
enough, you'll find that OSPF isn;t supported (eg on 800 series)
note that with ISIS, you can change the Pseudo node at will, (equiv to DR)
by changing the isis priority.
regards
Adam
> ----------
> From: ccie2be[SMTP:ccie2be@nyc.rr.com]
> Reply To: ccie2be
> Sent: Wednesday, August 06, 2003 11:16 AM
> To: Group Study
> 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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