hi ,
To say in non-technical terms, quit gr or not quit gr makes no
difference. ( I mean my cup is atleast half full, instead of calling
it half empty).
There are many other protocols dependending on OSPFv2 GR, so we better
not to a real Quit for the following reasons.
Here is the order of convergence required in major networks during
graceful restart.
1) Layer 2 convergence (control plane information)
2) Layer 3 OSPF/ISIS -> MPLS (Shim Protocols) -> BGP
3) Final convergence of all protocols.
In step 2, if you quit GR what would happen to MPLS and BGP convergence
?.(Dont forget the big deal BGP recursive
route selection )
GR will work even if you dont follow the RFC completely. ( You might
consider both the Graceful re-start draft and update
to graceful restart draft as informational) to help you realize the GR
which can work.
Abhay
P.S: Real quit might include restarting the router's software processes
disgracefully.Again there is no difference is it ?
sujay gupta wrote:
Hi Amir,
Adding ;
If the link between R1-R2 toggles making the adjacency going down and
then come up.R1 should exit GR.
R2 should exit helper mode send an inconsistent LSA to R1, R1 on
examining this LSA should exit GR.
Or; alternately R1 could detect a Nbr Down event and immediately exit
GR.
Regds,
-Sujay
( Ref http://tools.ietf.org/wg/ospf/draft-holla-ospf-update-graceful-restart-02.txt
Section 3.2.1(1))
On 11/10/06, Abhay D.S <[EMAIL PROTECTED]> wrote:
dear amir,
There is nothing called as Quitting GR.
In the case below , the most desirable thing is to give a message or an
SNMP trap for qualifying to a quit scenario.
There is a thin line between completion and quitting GR. Just imagine
this happens when the last router was about to be
full and re-starter was just about the originate old router LSA ,
perfectly as the old one and then this event happened ?
Would you quit GR or log a message.
Another is what is your idea of quit GR ?.
Thanks,
Abhay
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(when R1 and R3
are in transition state) the adjacency between R1 and R2 goes down for
some reson.
Considering above scenario, my doubts are:
- As the
adjacency between R1 and R2 has gone down(which is a Topology change)
and R1 is still in GR mode, can R1 quit GR ? In general can a NBR which
was FULL and then later gone down can be treated as one of the
conditions for quiting GR ?
Regards
Aamir
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