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Re: Unofficial IP addresses

To: nv-l@lists.tivoli.com
Subject: Re: Unofficial IP addresses
From: "Prokott, Joe" <Joe.Prokott@WESTGROUP.COM>
Date: Wed, 10 Feb 1999 21:51:45 -0600
Reply-to: Discussion of IBM NetView and POLYCENTER Manager on NetView <NV-L@UCSBVM.UCSB.EDU>
Sender: Discussion of IBM NetView and POLYCENTER Manager on NetView <NV-L@UCSBVM.UCSB.EDU>
I do not think this will work since NV will not depict (at least with a
single NV system) in the maps the same IP address on multiple different
nodes.  NV does not "know" how IP address X.X.X.X on system A should be
displayed in the NV maps vs. the same IP address X.X.X.X on system B.  NV
will just discover the first UNIQUE IP address and get its properties
(remaining IP addresses, sysContact, etc...).  It will then generate the
event "Duplicate IP address Y.Y.Y.Y found on NODE A and NODE B" at regular

Even being that you have separate MLMs managing the duplicate addresses
separately, I do not think the centralized NV system gathering the info.
from the MLMs will put the duplicate addresses into the one centralized NV
map database correctly (or at least the way you want to see them).  Even if
it could, how could it determine and properly display in the maps the subnet
X.X.X.Y at physical location 1 vs. the same subnet X.X.X.Y at physical
location 2?  If properly maintained, you could maybe get unique Selection
names for each node (e.g., "hostname", etc...) and interface (e.g.,
"hostname:Serial0/1", etc...) in the NV database so long as you used UNIQUE
node names across all managed devices, but you will still likely struggle
with getting all of these devices to show the way you want them within the
one centralized NV database (i.e., Node A AND Node B with IP address X.X.X.X
will show up under subnet icon X.X.X.Y in the NV maps, even though the nodes
are at two physically different locations.).  You may?? be able to get
around this if you use the /etc/networks file to also UNIQUELY define your
subnet names for all managed subnets across your enterprise (this would
ensure a unique "Selection Name" in the NV database for each subnet once you
merge the data from the multiple MLMs together to the centralized NV

If you could get these all into the one NV database without database
conflicts, you should be able to create NV collections of the nodes without
map accuracy conflicts, since this method of viewing the nodes is not
dependent upon network topology, but rather only on how you define the rules
that define the NV collections (e.g., all nodes where "sysLocation=SiteA",

There are a lot of maybe's in this response, perhaps some others can provide
better feedback on their own experiences in trying to do this. Good luck and
let us all know if you can get this to work, as I think many of us struggle
with these duplicate private IP addresses, especially from acquisitions
where we inherit the IP addresses and management of new networks.

Joe Prokott
Network Architect
West Group
St. Paul, MN  55123
e-mail: joe.prokott@westgroup.com

-----Original Message-----
From: Fältman, Mikael [mailto:mifal@WMDATA.COM]
Sent: Wednesday, February 10, 1999 3:26 PM
Subject: Re: Unofficial IP addresses

I must clarify one thing.
This problem is only related to topology and map handling.
For snmp-traps and syslog messages we have a separate 
distributed system that won't be affected.

> ---
> Mikael Fältman (mifal@wmdata.com)
> Network Services
> WM-data Infrastruktur AB, BOX 164, S-295 22 BROMOLLA
> -----Original Message-----
> From: Fältman, Mikael 
> Sent: den 10 februari 1999 19:10
> Subject:      Unofficial IP addresses
> Until now we have had control over our customers WAN IP addressing but
> now customer after customer is converting to unofficial IP addresses.
> Since we have a centralized monitoring (NV 5.1 AIX) this is a great
> problem.
> A customers network is typically between 10-50 routers and we monitor
> about 1000 routers.
> Using NAT:
> Not good. Since we have to monitor every interface on each router using
> NAT 
> will course Netview to find double interfaces on every router (the real
> and the fake) and
> the fake will ofcourse be red. This is just to hard to handle.
> One Netview for each customer:
> To many operator consoles and to much NV administration.
> Also very expensive !
> Can you get every customer topology into the main Netview ? (not, they
> might have same IP addresses)
> Is this possible to handle and to keep topology at all ?
> Is this a possibility ?
> Customer-A has 10.0.x.x addresses like Customer -B also have.
> The two customers networks are separated ofcource and have one Netview MLM
> each.
> The two NVs reports back to a central Netview. This won't work since the
> two MLMs will
> report the same IP addresses. Is it possible to tamper (via API) the IP
> addresses within
> one of the two MLMs sort of a internal MLM NAT function so that one MLM
> will report
> different IP addresses ?
> I find this very hard to explain and I hope some of you understand my
> problem.
> Any suggestions ?
>       ---
>       Mikael Fältman (mifal@wmdata.com)
>       Network Services
>       WM-data Infrastruktur AB, BOX 164, S-295 22 BROMOLLA

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