Re: Update to OSPF Hello procedure[draft-kou-ospf-immediately-replying-hello-00.txt]

[Erblichs <[e-mail]>]

Kou,

	1) A few extra hellos? You will force a matrix number
	   of hellos? With 10 routers, you will need 90 hellos.
	   With 100 routers, we have 9900 hellos I think, if
	   we need to respond to each nbr's hello. Where we have
	   2x the number of router's hellos in the standard method
	   with MC hellos (20 and 200). Oh, yours are with ms of
	   each other and the standard hellos are spread along the
	   hello interval.

	2)
	I disagree, this can effect DR election.

	How? Assume their is a disagreement as to whom
	should be elected DR in the normal method. Now, with
	that quick hello, the faster router tells the other
	routers not just whom he choose, but who is the DR.

	Anytime before DR is elected, Y informs that X is the DR,
	then OSPF says X is the DR. You are saving on avg
	1/2 hello interval time.

	Now, why can their be a disagreement? Simply, a late
	hello informing about a new router with a higher priority
	before the DR is elected.

	With the current method, we give an extra few secs, just
	to allow everyone to make up their own private decision, then 
	publicise the decision, and if their is a disagreement after
	recieving the multiple public hellos, then resolve it.

	Yes, some implimentations ignore hellos with DR announcement
	after election has begun. But some don't. And I am refering
	to the later ones.

	Now, it gets complicated. Assume that 2 routers who accept
	the fast hello and the interruption of the DR process. Won't
	they form a full ADJ if one or both are the DR / BDR? Now,
	the 3rd guy heard a hello from the highest priority router
	and accepted him as the DR? Aren't you needlessly trying
	to sync the LSDBs with the wrong DR?

	Mitchell Erblich
	
	

Zengjie Kou wrote:
> 
> Hi,Manav
>     I don't find any harm except a few additional hello packets before the state reaches "ExStart".
> 
>     The Immediate Hello do not affect which router will be elected DR. It only expedite the election.
> 
> thanks
> kou.
> 
> ----- Original Message -----
> From: "Manav Bhatia" <[e-mail]>
> To: <[e-mail]>
> Sent: Thursday, December 29, 2005 7:27 PM
> Subject: Re: Update to OSPF Hello procedure[draft-kou-ospf-immediately-replying-hello-00.txt]
> 
> > So whats the harm in this?
> >
> > If you wanted a particular router to become the DR then you would have given it a higher priority.
> > The fact that you havent done that implies that you dont really care which router becomes the DR.
> >
> > Manav
> > --- Nitin Kakkar <[e-mail]> wrote:
> >
> >> Suppose there are n routers on a Link and all of them come up almost
> >> simultaneously.
> >>
> >> Seems like the routers which were fractionally faster to send hello will be
> >> picked for DR/BDR election !!!
> >>
> >>
> >>
> >> May be you can think of  immediately replying to hello packet "Only when DR
> >> is already elected on the link".
> >>
> >>
> >>
> >> Rgds
> >>
> >> Nitin
> >>
> >>
> >>
> >> -----Original Message-----
> >> From: Mailing List [mailto:[e-mail]] On Behalf Of
> >> Kouzengjie
> >> Sent: Thursday, December 29, 2005 7:51 AM
> >> To: [e-mail]
> >> Subject: Update to OSPF Hello
> >> procedure[draft-kou-ospf-immediately-replying-hello-00.txt]
> >>
> >>
> >>
> >> A New Internet-Draft is available from the on-line Internet-Drafts
> >> directories.
> >> The draft can be found here:
> >> http://www.ietf.org/internet-drafts/draft-kou-ospf-immediately-replying-hell
> >> o-00.txt
> >>
> >>
> >>
> >>  This memo documents an extension of the OSPF protocol to reach
> >>    "ExStart" state more quickly. Currently, the OSPF behavior requires
> >>    the Hello Packet to be sent between the neighbors every
> >>    HelloInterval. This document proposes to generalize the use of
> >>    Immediately Replying Hello which could reduce the time required to
> >>    reach the OSPF "ExStart" state and  expedite the routing table
> >>    convergence.
> >>
> >>
> >
> >
> >
> >
> > ___________________________________________________________
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