RE: [OSPF] OSPF GR query

Fri, 15 Sep 2006 10:45:31 -0700

Title: [OSPF] OSPF GR query

Amir,

 

Per section 2.2 item 2, R2 will exit GR because it receives a router LSA from

R3.  Alternately, it will receive a new network LSA from the DR containing

R3.

 

When R2 receives ANY new router LSA during its restart, it will terminate.  This

clause should also probably extend to network LSAs as well.

 

Actions to take on exiting GR are described in section 2.3 and apply whether

the exit was “graceful” or “ungraceful”.  There’s no necessity to go back to the

down state.  There will just be additional items to be exchanged.

 

-don

 

From: Khan Amir-G20247 [mailto:[EMAIL PROTECTED]
Sent: Friday, September 15, 2006 8:53 AM
To: [email protected]
Subject: [OSPF] OSPF GR query

 

 

Hi

I have query related to Strict LSA Checking in OSPF Graceful Restart.

Consider this scenario:

- Two Routers R1 and R2, connected with a Broadcast network.
- Where R1 is a DR and R2 as DR-other
- Now R2 wants to perform GR and R1 agrees to be its Helper.
- Now after restart R2 will try and form adjacency with R1.
- Lets say that R1 and R2 had reached Exstart state. Now at this time another router R3 joins the network.
- This router R3 will effect the contents of R1 LSDB.
- Now if Strict LSA Checking is enabled, R1 will quit from Helper mode.
- After quiting R1 will recalculate DR/BDR and will reoriginate router LSA and network LSA.

 

Considering above scenario, my doubts are:

- How will R2 come to know that its Helper has quit ?
- When will R2 exit GR ?
- As the NBR state had reached to Exstart before R1 exited, will state be back to Down and  
  the adjacency formation will start all over again, once R2 exits GR ?

 

Regards
Aamir 

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