From: Eric Phillips (eric@phillips.tc)
Date: Thu Feb 05 2009 - 14:43:57 ARST
Hi Wiz,
One item that comes to mind about subinterfaces vs the main interface could
be frame relay end-to-end keepalives. While it is not specifically OSPF
related, I could envision a question whereby you have a PPP serial link and
a FR link between two routers, and there is a question in the OSPF section
that says something to the effect of "absolutely no traffic should traverse
the PPP link unless the FR link is down." Being in the OSPF section you
might assume "ip ospf demand-circuit" would be the correct answer, but some
traffic flows at the start of the sessions. So perhaps FREEK+backup
interface is the correct answer. And of course FREEK will not shut down a
physical interface, else you would never see the FREEK frames arrive when
the DLCI comes back up.
That is a big stretch, and I would definitely ask the proctor if the initial
OSPF neighbor setup traffic was allowed, and if suppressing hellos and
periodic LSA flooding was sufficient.
Eric M. Phillips CCIE #23378
On Thu, Feb 5, 2009 at 8:48 AM, Wiz Khan <wiz.ccie@gmail.com> wrote:
> Hello,
>
> Are there any differences on Frame Relay main interface and Multipoint sub
> interface with respect to OSPF.
>
> I see that both are Type NON_BROADCAST and Hello 30, Dead 120
>
> Any other differences that come to mind from lab perspective?
>
> Thanks,
>
>
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