ITEM: AT9980

NetView - REMOVED status in database

Question:

I've been building a new map by copying and pasting objects from the
discovered Applications plane to submaps that I create in the User plane.
Everything has been working more or less ok until yesterday when I noticed
that NV was apparently (erroneously) removing objects from my map!

The nodes, routers, etc. still show up on the locate submap list. They are
flagged as "REMOVED: on ovobjprint and in the attributes.

The removed nodes are, in fact, alive and well and are reachable, pingable,
etc. In some cases, entire subnets and their contents were removed.

This is kind of rude behavior on the part of Netview, I think. If discovery
won't add objects that are in any one of the maps in my database, why is it
so happily deleting valid devices from the configuration?

1) Why did NV do this and what can I do to make sure it doesn't happen again?

2) How do I restore these objects without going thru the copy/paste deal all
over again?

Answer:The first issue is "Why are symbols being deleted from my maps?"

The netmon daemon is the daemon that monitors your network for new
nodes, node status, and node configuration changes.  Under a few
conditions, netmon may decide that nodes should be deleted from
your databases.

The most common reason for deletion is that a node has not responded to a ping
within a particular time period.  This time period is configurable -
the default is 7 days.  Make sure that this has not been set accidentally,
to, say, 5 minutes.

netmon will also delete IP addresses if:
  1) an snmp agent says that the IP address does not belong in the
     node to which it has already been assigned, or
  2) two separate nodes report the same IP address.

This is a bit harder to diagnose.  You might want to make sure that
you don't have duplicate IP addresses in your system, and that your
the snmp agents on your nodes (especially on your routers) are behaving
correctly.

To determine exactly what netmon is thinking when it deletes nodes,
you can begin a netmon trace by typing the following command:

  netmon -M -1

This might tell why netmon is deleting these nodes.

***

The second issue is "When netmon deletes these nodes, why don't all
of the symbols disappear, and why are the objects just marked as
REMOVED?"

The answer to this is complex, but here's the short answer:

Let's say that netmon wants to delete an object.  If there are
symbols on the map that correspond to that object, then netmon must
wait for the ipmap application to delete the symbols for that object
before the object itself (the object in the Object database) can
be deleted.

Normally, ipmap deletes all of the symbols for the object, and then the
object is deleted, and all is well, and no aspirin is necessary.

However, when you make copies of symbols, you create new symbols for
an object, and you place them in the User plane, out of ipmap's
jurisdiction.  When ipmap gets the word to delete the symbols, it
deletes all of its symbols, but it can't delete YOUR symbols (you might
not want them deleted... right?), so the object is just marked as
REMOVED.  This is your cue to use the Edit..Delete Object command
to delete the object from the User Interface.  At that time, the
object is deleted from the databases.

******

To avoid this in the future, I recommend a few steps:

  1) Upgrade to Version 3 as soon as you can, and make sure that
     you have configured netmon correctly (if you use secondary addresses,
     set that option, if you use Unnumbered IP addresses set that option,
     etc.)
  2) Verify that community names and IP addresses in your network
     are set correctly.
  3) Rediscover your network (you don't have to do this, but it
     will probably help in the long run... you can use a netmon
     seed file to expedite this if you like).
  4) Don't make symbol copies if you can keep from it.  If you want
     to move symbols from one submap to another, use the cut and
     paste functionality rather than the copy function.  This
     is all documented in the Version 3 documentation.




Support Line: NetView - REMOVED status in database  ITEM: AT9980

Dated: January 1996 Category: N/A

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