My vote goes to D (and B, but I don't think that's under dispute). OK, so
'excessive' is subjective, but then so is 'large'. The question's not asking
WHEN the problems will occur, or even claiming that problems will occur in all
circumstances, just asking what POSSIBLE problems there are.
My reasoning is that as the number of networks increases, the number of LSAs
increases, but the number of adjacencies each router has doesn't necessarily
increase (by much). The question implies single OSPF area, so summarisation
doesn't come into the picture. Given a finite amount of memory, CPU etc on
routers, a 'large' number of networks will cause a 'large' number of LSAs, which
have to be refreshed every 30 minutes regardless of network changes, which
causes traffic, CPU usage, etc - and potential problems. Especially if you
interpret 'large' as 'large enough to cause problems'.
JMcL
---------------------- Forwarded by Jenny Mcleod/NSO/CSDA on 15/11/2000 09:24 am
---------------------------
"Chuck Larrieu" <[EMAIL PROTECTED]> on 15/11/2000 07:11:13 am
Please respond to "Chuck Larrieu" <[EMAIL PROTECTED]>
To: "Priscilla Oppenheimer" <[EMAIL PROTECTED]>
[EMAIL PROTECTED]
cc: (bcc: JENNY MCLEOD/NSO/CSDA)
Subject: RE: Single area with large number networks.
But if the "right" answer consists of two choices.......
I believe we all agree that B - frequent routing recalculation - is
"correct"
I believe we all agree that A - more reachable errors - is BS
Of the two remaining choices, which is least wrong?
My reasoning was that C - frequent adjacency table recalculation - is
irrelevant because an OSPF router forms adjacencies only with directly
connected neighbors, and not necessarily with every router in the area. The
result of the "show IP OSPF neighbor" command, even in very large networks,
would be relatively small.
That leaves D as being the other "correct" answer. Yeah, I see your point,
Priscilla. On the other hand, all of us have seen a wide variety of
terminology for the same think. Link state database, link state table, OSPF
table, OSPF database, and so on. It is not unreasonable to conclude that the
test writer has his or her own jargon for what we call the OSPF database.
If D is wrong, then the choice is C, and that's problematic.
Chuck
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of
Priscilla Oppenheimer
Sent: Tuesday, November 14, 2000 11:33 AM
To: [EMAIL PROTECTED]
Subject: RE: Single area with large number networks.
At 09:36 PM 11/14/00, Ibrahim wrote:
>thanks for your response.
>But if some router down, the nearest one will send message to DR & BDR, and
>DR will send multicast message (it won't be excessive) to its networks.
I agree it wouldn't be excessive. Within a LAN, the DR mechanism keeps
adjancies and LSA propagation from getting excessive. Between areas, the
number of LSAs would depend on summarization. So without more information
on the network topology, addressing, and configuration, we couldn't even
say when LSAs would be a problem.
Besides, as I look more closely at the answer, I see that it says,
"excessive link-state entries in the link-state table." What's a link-state
table? I think the test writer put a few good-sounding words together to
throw you off.
Conclusion: D is wrong.
This is the kind of thinking you should do to pass Cisco tests! &;-)
Priscilla
>thanks,
>Ibrahim
>
> >
> > IMHO, B is the best answer as link failures in the area will cause
> > recalculations.
> >
> > D is a possible answer; however, "excessive" is a subjective word:
OSPF
> > will generate the number of LSAs necessary to build its tables and the
> > picture of the network: it will not go beyond the number needed to do
so.
> > On the other hand, as a human, I may find a large number of LSAs
> > "excessive".
> >
> > HTH,
> >
> > Charles
> >
> > D is kind of subjective, but it
> > ""Ibrahim"" <[EMAIL PROTECTED]> wrote in message
> > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> > >
> > >
> > > doesn't help. I tried before. I also opened the CCIE : TCP/IP routing
> > book,
> > > ACRC book .. but can't found the answer.
> > >
> > >
> > > Ibam
> > >
> > > >
> > > > Try this
> > > > http://www.cisco.com/public/pubsearch.html
> > > >
> > > > ----- Original Message -----
> > > > From: "Ibrahim" <[EMAIL PROTECTED]>
> > > > To: <[EMAIL PROTECTED]>
> > > > Sent: Tuesday, November 14, 2000 11:52 PM
> > > > Subject: Single area with large number networks.
> > > >
> > > >
> > > > >
> > > > > Hi, this question is really confuse me :
> > > > > What are two possible problems that can occur when a single
> > OSPF area
> > > > > includes a large number of networks?
> > > > > a. more reachable errors
> > > > > b. frequent routing table recalculation
> > > > > c. frequent adjacencies table recalculation
> > > > > d. excessive link- state entries in the link- state table
> > > > > The frequent routing table recalculation is true, but what
> > > > about the other
> > > > > one ?
> > > > >
> > > > > thanks,
> > > > > Ibrahim
> > > > >
> > > > >
_________________________________
FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
