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Re: DR election

Hi Mitchell,
I don't see this as a strong requirement since one could always
configure a router priority of 0 on those routers which are not
able to hande the DR task. We've gotten along without this
DR preemption feature for this long and to the best of my knowledge
there aren't even any proprietary extensions to do this. This would
indicate to me that there is not a strong requirement.

As always, you are welcome to make such a proposal in
an individual draft for consideration by the WG.

Thanks,
Acee

Erblichs wrote:

Acee,

	Thanks' I just don't have the RFCs memorized
	to what section says what and yes, trying to solve
	a few gray issues to satisfy customers so I don't
	monitor this discussion on a daily basis.

	HOWEVER, Sorry,, I have to say more..

	The resulting re-election of the DR SHOULD NOT
	cause a major "churn", yes a minor churn.

	The reason is that if the re-election is done,
	their is no gurantee of a change in the DR, unless
	my suggestion of a delayed hello.

	If a new DR is elected, the previous DR would more
	than likely become the BDR or the BDR would stay
	the same. Thus, at least 1/2 of the full adjs
	are expected to stay the same.

	If this was an actual area combining event
	then the re-synch of the LSDB is necessary,
	else most of the LSDB updates would be on a 1
	way basis and only with the 1st full neighbor
	LSDB exchange.

	Yes, a minor churn, but if the new router has
	significantly higher capabilities than the present
	DR, I would see little reason not to at least
	consider this as a feature.

	Mitchell Erblich
	----------------


Acee Lindem wrote:


All,

This has been discussed before on this list and you could search
the archives to get all the gritty details. In summary:

  - The protocol attempts to avoid BDR/DR churn and the BDR/DR election
     gives the current BDR/DR precedence. The reason is obvious - you
want to
    avoid the network overhead/convergence delay of bringing up
    adjacencies with the new BDR/DR as well as  the
overhead/convergence delay
    of flooding and recalculating the intra-area route table with a new
DR's
    network-LSA.
  - While it is not part of the protocol specification, an
implementation could
     force a BDR/DR election by ignoring the fact that there is a
BDR/DR and
    asserting themselves as BDR/DR. They would cause a NeighborChange
    event (Section 9.2, RFC 2328) causing RFC 2328 compliant
implementations
    to perform a BDR/DR election.

Thanks,
Acee

Naresh Paliwal wrote:



Erblich,

I didn't get your reply, can u please give the references of the idea.

I mean to ask, is it possible to enforce DR/BDR-election without
changing configuration of existing DR/BDR?

Regards
-Naresh


-----Original Message-----
From: Mailing List [mailto:OSPF at PEACH.EASE.LSOFT.COM] On Behalf Of
Erblichs
Sent: Monday, May 02, 2005 10:07 PM
To: OSPF at PEACH.EASE.LSOFT.COM
Subject: Re: DR election

Yes and no,

If a router "really wants to be the DR", the protocol does
allow this through a back door. The router must act like
it was already also elected as the DR. This can happen in
what was a split area. By coming up later, the later router
SHOULD know the other's priority and router-id. It can then
boost its broadcasted priority and/or its router-id to gurantee
re-election.

Mitchell Erblich
----------------------


"Krishnan, Vijay G." wrote:




The first router does not become the DR immediately. It waits for its
configurable "wait timer" to expire, before electing the DR. Others




routers




could come up during this time. Once the DR is elected, addition of




new




routers would not change the DR. This will reduce the instability due




to the




DR changes.

regards
Vijay

-----Original Message-----
From: Mailing List [mailto:OSPF at PEACH.EASE.LSOFT.COM]On Behalf Of Ilan
Bercovich
Sent: Monday, May 02, 2005 11:51 AM
To: OSPF at PEACH.EASE.LSOFT.COM
Subject: DR election

Hello
If all routers accept the DR regardless of their Router Priority,
It means that actually the first active router on the LAN is the DR.
Isn't this makes the Router Priority parameter somewhat irrelevant?
(In RSTP for instance, when priority is changed - network is
re-calculated).
Ilan