Re: [OSPF] OSPF GR query

Hi Sujay,
sujay gupta wrote:
> Hi Acee,
> A late mail on this thread.
>
> given the scenario if R3-R1 is a stub area
> and the incoming LSA is a type-5, even with strict LSA
> checking enabled will not exit Helper mode.
I'm not sure what the network picture looks like but a helper
router can always terminate graceful restart by flooding an
inconsistent router or network LSA to the restarting  router.

Thanks,
Acee

>
> It can be a nice idea to give some explicit notification
> by R2 to R1 about exiting helper mode.
>
> As rightly pointed by you the above conditions and more
> has been causing some confusion for some time.
> Our proposal ;
> http://tools.ietf.org/wg/ospf/draft-holla-ospf-update-graceful-restart-02.txt 
>
> hopefully resolves this.
> Could we add this as an addendum/reference to RFC3623?, purely an
> add-on.
> Best Regards.
> Sujay
>
> On 10/5/06, Acee Lindem <acee@cisco.com> wrote:
>>
>> Khan Amir-G20247 wrote:
>> > Hi Ace
>> >
>> > But reaching to a FULL state is not one of the conditions for 
>> Helper to
>> > quit Helper mode, I guess a Helper who has reached
>> > to FULL state with its restarting router will wait for Grace LSAs 
>> to be
>> > flushed or GR timeout to happen for exiting Helper mode.
>> >
>> No - The presumption is when you reach FULL state you don't need to 
>> "quit"
>> helping - you have "finished" helping. Over the years, there have been a
>> few situations that could have been better documented - however, this
>> never
>> caused any confusion in the past.
>>
>> Thanks,
>> Acee
>>
>> > Regards
>> > Aamir
>> >
>> >
>> > -----Original Message-----
>> > From: Acee Lindem [mailto:acee@cisco.com]
>> > Sent: Thursday, October 05, 2006 8:00 PM
>> > To: Khan Amir-G20247
>> > Cc: ospf@ietf.org
>> > Subject: Re: [OSPF] OSPF GR query
>> >
>> > Hello Amir,
>> >
>> > Khan Amir-G20247 wrote:
>> >
>> >>
>> >>
>> >> Hi
>> >>
>> >> I have query related to OSPF Graceful Restart.
>> >>
>> >> Consider this scenario:
>> >>
>> >>
>> >>
>> >> - Three Routers R1, R2 and R3 connected via Broadcast networks.
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >> - Where R1 is a DR on both the segments, where as R2 and R3 are in
>> >> DR-other
>> >> - Now R1 wants to perform GR, R2 and R3 agrees to be its Helpers.
>> >> - Now after restart R1 will try to form adjacency with both R2 and 
>> R3.
>> >>
>> >
>> >
>> >> - Lets say R1 and R2 had become FULL, while R1 and R3 had reached
>> >> Exstart state.   Now at this time R2 receives an LSA (any type 1-5 
>> and
>> >> 7, from some other router existing in the same area, not pictured
>> >> here) which he needs to flood to R1.
>> >> - This will force R2 to quit Helper Status, while R1 and R3 are still
>> >> in process of forming adjacency.
>> >>
>> >>
>> > Since he has reached FULL state, he is no longer a helper router.
>> >
>> >> Considering above scenario, my doubts are:
>> >>
>> >> - How will R1 come to know that its Helper R2 has quit?
>> >>
>> >>
>> > Since he has reached FULL state, he is no longer a helper router.
>> >
>> >> - Will the adjacency between R1 and R2 needs to go down, as R2 quits
>> >> helper mode?
>> >>
>> >>
>> > No
>> >
>> >> - Will this effect the adjacency formation of R1 and R3?
>> >>
>> >>
>> > No. R3 MAY exit helper status and re-originate a new router LSA if he
>> > receives the new LSA before reaching FULL state with R1 AND he is has
>> > strict-LSA-checking configured.
>> >
>> > Hope this helps,
>> > Acee
>> >
>> >>
>> >>
>> >> Regards
>> >> Aamir
>> >>
>> >>
>> >>
>> >>
>> >>
>> >> 
>> ----------------------------------------------------------------------
>> >> --
>> >>
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>> >>
>> >
>> >
>>
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>

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