Subject: [OSPF] OSPF graceful restart

From: "Santosh P K" <[email-masked]>
Date: Thu, 6 Sep 2007 08:47:46 +0530

Hi All,
      In RFC 3623 section 3, it says
                     " When helping over a virtual  link, the helper
must also continue to set bit V in its router-LSA for the virtual
link's transit area (Section 12.4.1 of [1])."

1. Does the restarting router need to unicast the Grace-LSA to virtual
neighbor?

2. RFC Appendix A says
   "Grace-LSAs have link-local scope because they only need to be seen by
   the router's direct neighbors"
    In this case the virtual neighbor will never see the grace LSA and
hence will not enter in to helper mode.

now for example

    lo------(area 0)R1 (area 1)----------- R2 (area
1)--------------(area 1)R3----lo(area 2)
                         |_______________Virtual link_______________|

There is a virtual link on area 1 between R1 and R3. Now R1 is the
router that gracefully restarts and sends a link local grace LSA. What
I understand from the above mentioned points is that R2 has to take
care of the virtual link and there will be no Grace LSA sent over
virtual link to R3 as its not directly connected to R1 but sent to R2.

Please correct my understanding is totally wrong.

Thanks and regards
Santosh P K

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From: Acee Lindem <[email-masked]>
Date: Thu, 6 Sep 2007 10:46:39 -0400

Hi Santosh,

> hence will not enter in to helper mode.

Nope - A link-scoped LSA is sent on the virtual link once the  
endpoint is reachable and the link comes up.

Hope this Helps,
Acee