From: ccie2be (ccie2be@nyc.rr.com)
Date: Fri Jul 18 2003 - 16:44:19 GMT-3
Hi all,
I figured out the problem. Take note because this (at least for me) was
very non-intuitive.
The reason the command, "area 0 range 172.16.123.0 255.255.255.0" worked on
rtr1 and rtr3 is b/c both rtr1 and rtr3 are ABR's also connected to area 1.
In fact, a show ip route on other routers in area 1 verified that both rtr1
and rtr3 were advertising the summary route 172.16.123.0/24 into area 1.
rtr2, however, was not an ABR, it was ASBR and therefore ignored the area 0
range command. Subnets summarized with the command area 0 range x.x.x.x
m.m.m.m will only be advertised into other non-backbone areas - NOT TO
ROUTERS ACROSS THE BACBONE which is why rtr1 and rtr3 didn't advertise the
summarized subnet to rtr2. (Actually, I'm not 100% of the accuracy of the
previous statement b/c a show ip os on rtr2 showed the following:
172.16.123.0/24 Passive Advertise so maybe the subnet is advertised but
routers in area 0 that receive the advertisement don't do anything with it.)
The problem was quickly and easily fixed when rtr2 was made an ABR.
This problem was discovered, one could say, by accident. The IPexpert
pratice lab instructions said to place all interfaces on rtr2 in area 0.
This caused the problem and was obviously a mistake in the lab instructions.
I'm glad I ran into this problem and finally figured out the solution but I
wonder if I could have learned as much in a much shorter amount of time and
without the days of frustration.
Raj
----- Original Message -----
From: "ccie2be" <ccie2be@nyc.rr.com>
To: "Group Study" <ccielab@groupstudy.com>; "Jonathan V Hays"
<jhays@jtan.com>
Sent: Friday, July 18, 2003 2:34 PM
Subject: Re: Reward Offered to first person with correct answer to ospF
problem
> Hi Johnathan,
>
> The issue in this scenario isn't IGRP; it could have just as well been rip
> v1. The problem has to do with summarizing a a subnet so that it can be
> redistributed into a classful routing protocol.
>
> Regarding the reward, I realize that not everybody lives in the NYC area,
> however, since there's no stature of limitation and NYC is one of the most
> visited cities in the world, I suspect the winner will at some point be in
> NYC to claim their justly deserved reward. There's even the possibility
> that if by the time the winner claims their reward I happen to have passed
> the lab, my wife will feel such graditude she might even throw in a
gourmet
> dinner. :-)
>
> Here's a copy of the original post:
>
>
> Rtr1, rtr2, and rtr3 are ospf backbone routers connected via f/r
> 172.16.123.0/29 with rtr2 as the hub.
>
> rtr2 is also redistributing routes into igrp. Since igrp is classful, the
> subnet 172.16.123.0/29 is being summarized into a /24 with the command,
> "area
> 0 range 172.16.123.0 255.255.255.0" on rtr1, rtr2 and rtr3.
>
> On both rtr1 and rtr3, in the routing table there's the entry,
> "o 172.16.123.0/24 is a summary ..... null 0",
>
> However, there's no such entry on rtr2.
>
> In addition, on rtr2, in the output of "show ip ospf" it has the
following,
>
> Area Backbone (0)
> <text omitted>
> Area Ranges are
> 172.16.123.0/24 Passive Advertise
>
>
> rtr2 config:
>
> int s0.123 multi
> ip addr 172.16.123.2 255.255.255.248
> fram map ip 172.16.123.1 221 broad
> fram map ip 172.16.123.3 223 broad
> ip ospf priority 5
>
>
> router ospf 1
> net 172.16.123.0 0.0.0.7 area 0
> area 0 range 172.16.123.0 255.255.255.0
> redist igrp 1 subnet
>
>
> In addition, sh ip os nei on rtr2 shows that rtr1 and rtr3 are neighbors
and
> all other summarized subnets are succesfully being redistributed into
IGRP.
> (Rtr 2 is connected to rtr4 which is running only IGRP and the route table
> on rtr4 shows that all subnets except 172.16.123.0/24 are being learned
from
> rtr2
>
>
> Why is that? I want 172.16.123.0/24 to be advertised. In fact, the
reason
> 172.16.123.0/24 is being summarized is so that it can be redistributed
into
> igrp.
> Other subnets are being summarized and redistributed into igrp just fine.
> What needs to be done so that 172.16.123.0/24 is not "Passive Advertise"?
> I've been trying different things to fix this for hours, but without any
> success. Please end my misery and confusion.
>
> ----- Original Message -----
> From: "Jonathan V Hays" <jhays@jtan.com>
> To: "'ccie2be'" <ccie2be@nyc.rr.com>; "'Group Study'"
> <ccielab@groupstudy.com>
> Sent: Friday, July 18, 2003 1:31 PM
> Subject: RE: Reward Offered to first person with correct answer to ospF
> problem
>
>
> Raj,
>
> Since very few of us live in that area, I think a couple of thousand US
> dollars via PayPal would be a more reasonable reward, don't you? <G>
>
> If you have limited time and are spending it in serious preparation for
> the CCIE R&S lab exam, I have to ask: why even bother with IGRP? The
> IGRP protocol has not been on any CCIE Lab since October 31, 2002. Cisco
> specifically says it won't be on the lab here:
> http://www.cisco.com/en/US/learning/le3/le2/le23/le7/learning_certificat
> ion_type_home.html
>
> If you really want help with this scenario, please post complete,
> unedited configurations of all three routers, along with "sh ip route".
> Doing that is more likely to get people interested in your problem
> because we won't be playing a back-and-forth guessing game about how you
> have everything configured.
>
> Post your configs.
>
> Jonathan
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> ccie2be
> Sent: Friday, July 18, 2003 12:53 PM
> To: Group Study
> Subject: Reward Offered to first person with correct answer to ospF
> problem
>
>
> Hi group,
>
> This morning at 9:01, I posted an ospf problem regarding summarizing an
> area 0
> subnet so that it can be redistributed into igrp. This problem
> continues to
> baffle me, so I am offering a reward of free drinks to the first person
> who
> provides the correct solution and a clear explanation. The reward can
> be
> collected at your choice of any establishment in Manhattan or Queens
> (other
> NYC tri-state locations are also possible).
>
> I've spent too many hours on this problem and I need to move on to other
> labs,
> but I'd like to understand what the #$%&*( is going on before
> starting
> on something else.
>
> See my post (from ccie2be re: OSPF passive advertise) for a full
> description
> of the problem and feel free to request additional info if anything is
> unclear. Raj
>
>
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