[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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

Zengjie Kou wrote:

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.


Hi Zengjie,

I don't think there should be a distinction between first coming or coming back up.

Thanks,
Acee

Thanks,
Zengjie

----- Original Message ----- From: "Acee Lindem" <acee at CISCO.COM>
To: <OSPF at PEACH.EASE.LSOFT.COM>
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" <acee at CISCO.COM>
To: <OSPF at PEACH.EASE.LSOFT.COM>
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" <acee at CISCO.COM>
To: <OSPF at PEACH.EASE.LSOFT.COM>
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