Re: Doubt on sending hello packets on NBMA networks

[Kishore Rao <kishore at IND.ALCATEL.COM>]

Possible scenarios ?

- Timing difference between dynamically changing the eligibility
configuration/setting interface priority Vs sending of a Hello.
- Mismatch in configuration between interface priority of a router and its
eligibility configuration on other routers.

Kishore


> hi Acee,
>
> yeah i got it. but just for the sake of curiosity. can you give me
> some more scenarious where this can happen?
>
> Thanks
> Srini
>
> -----Original Message-----
> From: Acee Lindem [mailto:acee at CISCO.COM]
> Sent: Monday, May 09, 2005 6:40 PM
> To: OSPF at PEACH.EASE.LSOFT.COM
> Subject: Re: Doubt on sending hello packets on NBMA networks
>
>
> Srinivasa J Ragavan wrote:
>
> >hi All,
> >
> >I am a newbie to OSPF.
> >can anyone help me out.
> >this is with reference to the rfc 2328 sec. 9.5.1 whcih says
> >"  If the router is eligible to become Designated Router, it
> >            must periodically send Hello Packets to all neighbors that
> >            are also eligible."
> >
> >but immediately in the next paragraph it says
> >
> >" It must also send an Hello Packet in reply to an
> >            Hello Packet received from any eligible neighbor (other than
> >            the current Designated Router and Backup Designated Router)"
> >
> >how can a non eligible router get a hello from a eligibe router if the
> >eligible router is not going to send(tatz what the first argument says)
> >
> >
> Srini,
> In the NBMA case (which is described in section 9.5.1), a non-eligible
> router
> needs to reply to any eligible neighbor since it may not know the current
> DR/BDR. There are a number of scenarios where this can happen including
> the case where the non-eligible neighbor first comes up and receives a
> hello poll
> from the current DR/DBR. The non-eligible neighbor needs to establish
> bi-directional connectivity with the potential DR/BDR in order for its
> local DR/BDR election to work.
>
> Hope this helps,
> Acee
>
>
> >Am i missing something here??
> >
> >thanks
> >Srini
> >
> >
> >
> DISCLAIMER
> This message and any attachment(s) contained here are information that is
confidential, proprietary to HCL Technologies
> and its customers. Contents may be privileged or otherwise protected by
law. The information is solely intended for the
> individual or the entity it is addressed to. If you are not the intended
recipient of this message, you are not authorized to
> read, forward, print, retain, copy or disseminate this message or any part
of it. If you have received this e-mail in error,
> please notify the sender immediately by return e-mail and delete it from
your computer