Re: draft-kou-ospf-immediately-replying-hello-00.txt

[Zengjie Kou <[e-mail]>]

Hi, Acee
   The empty hello mechanism that you refered is adopted by most OSPF implementations indeed when an interface first comes up.
I agree this. However, when an normal interface whose state is up goes down then up, immediate hello  is  effective by avoiding 
helloInterval or backupSeen.

Thanks,
Zengjie
 
----- Original Message ----- 
From: "Acee Lindem" <[e-mail]>
To: <[e-mail]>
Sent: Thursday, February 23, 2006 5:41 AM
Subject: Re: draft-kou-ospf-immediately-replying-hello-00.txt


> Zengjie Kou wrote:
> 
>>Hi, Acee,
>>    You are right, immediate hello does not provide the mechanism of detecting link down fast. But, immediate hello improve to discover neighbors when interface goes down then up. In practice, the requirement is needed.
>>  
>>
> Hi Zengjie,
> 
> Speaking strictly in terms of state machines, it seems the interface 
> would lose it's DR/BDR state
> when it goes down (and cannot send a hello). Wouldn't this scenario be 
> better handled
> by the empty hello many OSPF implementations send when an interface 
> first comes up?
> 
> Thanks,
> Acee
> 
>>Thanks,
>>Zengjie
>>
>>----- Original Message ----- 
>>From: "Acee Lindem" <[e-mail]>
>>To: <[e-mail]>
>>Sent: Monday, February 20, 2006 11:15 PM
>>Subject: Re: draft-kou-ospf-immediately-replying-hello-00.txt
>>
>>
>>  
>>
>>>Hi Zengjie,
>>>
>>>Zengjie Kou wrote:
>>>
>>>    
>>>
>>>>Hi,Acee,
>>>>   If a router interface whose role is changed(e.g.DR goes down), the router will notify all routers about the change by immediate hello.
>>>> 
>>>>
>>>>      
>>>>
>>>This is only when the DR/BDR knows that it is going down or the case 
>>>where the router
>>>priority is set to 0.
>>>
>>>For a router becoming DR/BDR, all the routers should elect the same DR/BDR
>>>so I don't see how it helps.
>>>
>>>Thanks,
>>>Acee
>>>
>>>    
>>>
>>>>After all router get the change, election will be reprocessed. In contrast to normal hello, immediate hello avoid the backupSeen.
>>>>Namely, improving convergence.
>>>>
>>>>Thanks a lot,
>>>>Zengjie
>>>>
>>>>----- Original Message ----- 
>>>>From: "Acee Lindem" <[e-mail]>
>>>>To: <[e-mail]>
>>>>Sent: Saturday, February 18, 2006 5:17 AM
>>>>Subject: draft-kou-ospf-immediately-replying-hello-00.txt
>>>>
>>>>
>>>> 
>>>>
>>>>      
>>>>
>>>>>Hi Zengjie,
>>>>>
>>>>>Under what situations does having the router who changed to/from
>>>>>DR/BDR improve convergence (section 6.2)? Since DR/BDR election
>>>>>is a distributed algorithm dependent on the calculating routers state, it
>>>>>seems this won't help in all that many cases.
>>>>>
>>>>>Thanks,
>>>>>Acee
>>>>>   
>>>>>
>>>>>        
>>>>>
>>>> 
>>>>
>>>>      
>>>>
>>
>>  
>>