Ok.. This is getting good. Books are all over the place: Round two "The
confusion continues".
Question 1.
I am quoting again from the exam cram acrc but its no bible either.
"BDR IP Address: The backup for the DR. It waits for half a second to hear
DR flooding updates. If the DR doesn't do its job, the BDR preempts and
passes the updates to all adjacent routers. A new BDR is then elected."
This sorta makes sense. When a router, say a third router, notices a change
it tells the DR via mutlicast on 224.0.0.6, which then tells all the
adjacent routers vial 224.0.0.5. The BDR is also listening on 224.0.0.6 is
just not responding. However, if the DR does not send out the LSA, the BDR
starts the work and send out LSA's to the adjacents. The time frame of .5
seconds makes sense.
However, if the router that dies is the DR then it would make sense that it
would take 4xhello to identify that the DR is gone.
Question 2.
>From the rfc(http://info.broker.isi.edu/in-notes/rfc/files/rfc2328.txt). So
my read of this is you always have a DR. but exam cram acrc says that it not
necessary in an nbma. So I would lean towards there is always DR it just
might not be useful. For this example it's just not necessary because the
whole concept of a DR-BDR is to minimize adjacencies but there is nobody to
worry about.
7.3. The Designated Router
Every broadcast and NBMA network has a Designated Router. The
Designated Router performs two main functions for the routing
protocol: The Designated Router originates a network-LSA on behalf
of
the network. The Designated Router becomes adjacent to all other
routers
on the network.
Question 3.
>You ran OSPF to customers? So you were selling them transit and used
>OSPF? I imagine the evil a customer could do to your network if they had
> access to an OSPF neighbor router.
I did not say it was bright. They had multiple T-1's and ospf allowed for
good load balancing without them having to get an AS. They learned routes
from me but I did not learn from them. That is pretty common I think.
-----Original Message-----
From: Brian [mailto:[EMAIL PROTECTED]]
Sent: Friday, November 10, 2000 11:28 AM
To: Matthew Herman
Cc: David Armstrong; [EMAIL PROTECTED]
Subject: RE: Some OSPF Questions
On Fri, 10 Nov 2000, Matthew Herman wrote:
> I'll throw my hat in..
>
> 1. .5 seconds (50 msec) (Chapter 7, p142 exam cram acrc)
you sure you're not thinking of HSRP?
> 2. yes, there will be only one DR and its your single point of failure as
> well 8->.
But not on PtP links, Their is no DR elected on a Point to Point link
> 3. doh...I have set up multiple as's on one router when I had multiple
> customer and redistributed into my AS. It worked ok but I am not saying
> that was a good way of configuring the router.
You ran OSPF to customers? So you were selling them transit and used
OSPF? I imagine the evil a customer could do to your network if they had
access to an OSPF neighbor router. Why not just static route to them as a
stub?
Brian
>
> 2/3 = 66 percent.... Still not enough to pass the ccie...
>
> matt
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
David
> Armstrong
> Sent: Friday, November 10, 2000 8:46 AM
> To: [EMAIL PROTECTED]
> Subject: Some OSPF Questions
>
> Last night at our BSCN study group meeting in Dallas we had some questions
> about OSPF that we weren't able to resolve. If someone or ones could
answer
> these it would clarify some areas we're a little fuzzy on. Also, if you're
> iin the Dallas Ft. Worth area and would like to attend, we'd love to have
> you join us..
>
> Thanks for any help,
>
> David Armstrong
>
>
> 1) What is the default time period that the BDR waits when listening to
> LSA's from the DR before it decides that the DR is down and promotes
itself
> to DR. All the literature we could find simply said that the BDR waits for
> the specified time period but never said what that period is.
>
> 2) In a Point-to-Point network in which the router in Area 0 is connected
to
> FR, ISDN, X.25 or ATM branch offices (networks), how does convergence and
> updates take place? From what we've found a DR and BDR is not elected in a
> strictly Point-to-Point network.
>
> I think an example would explain this question better: We have one 3620
> router in our Ft. Worth office connected to an office in Houston (via FR),
> and office in Kansas City (via FR), an office in the DFW area (via ISDN)
and
> the owner's home (via ISDN). The 3620 is behind a firewall (Pix 520) and
the
> firewall is connected to a 1720 going to the Internet. I'd like to
implement
> OSPF on our network simply for the experience. However, I don't have 2
> routers internally on our Ethernet LAN that can be configured for Area 0
and
> elected to DR and BDR. All other routers connected to that router are via
> NBMA Point-to-Point connections. Since I only have one router on the
> Broadcast Multiaccess network (the 3620) and routers connected via PtoP
> don't participate in DR and BDR elections, how would updates occur? Can
> their only be one DR (in this case the 3620)?
>
> 3) The books and tutorials all state that "router ospf 6" defines ospf on
> the router with a process ID of 6. They then all say that you shouldn't
> define more than one process. Does that mean that you can have a router
with
> the following:
>
> router ospf 6
> network 10.100.0.0 0.0.255.255
>
> router ospf 7
> network 10.200.0.0 0.0.255.255
>
> If this is an allowed configuration, what kind of instances would it be
used
> for? Also, exactly what is the process ID used for?
>
>
>
>
> _________________________________
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> _________________________________
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-----------------------------------------------
Brian Feeny, CCNP, CCDP [EMAIL PROTECTED]
Network Administrator
ShreveNet Inc. (ASN 11881)
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