If your routers support it, I would recommend configuring a virtual loopback
interface with an IP address, and then define that IP address in your DNS.
Make sure that it is the only IP address defined in your DNS to avoid the
problem with round-robin. If there are multiple paths in your network, you
will also get the added benefit of better connectivity to your routers. For
example, if you have multiple IP addresses defined in DNS, and one of them
is not accessible because the interface is down, (or the path to that
interface is "broken"), then NetView will fail trying to access that router.
The round-robin support in DNS will help a little, because it will return
the next IP address the next time NetView queries that router. However, you
will still have failures. Loopback interfaces solve this problem because
the routers will automatically update their routing tables to provide a path
to the loopback interface when an interface is down (assuming there IS
another network path).
From: Julio W. Troya [SMTP:julio_troya AT HOTMAIL DOT COM]
Sent: Monday, August 24, 1998 15:50
To: NV-L AT UCSBVM.UCSB DOT EDU
Subject: NetView-T/EC-DNS Implementation Problem... HELP!
We are currently in the process of implementing DNS for our
NetView environment and have found a problem which we
Our environment consists of a NetView (5.0) server which feeds
multiple interface-router events to T/EC (3.1), and here's where the
problem manifests itself. Both servers are running with AIX 4.2.
Our NetView server is also configured as a secondary DNS server, and
whenever NetView resolves the host name to an IP address, it will
always return with a different primary IP address for the router.
It seems that it is selecting the next IP address in an
Because we get a different IP address for each event, T/EC is unable
correlate clearing events with old down events. For example, T/EC
will receive a node down event:
RG100BRA 10.0.7.131 Node down
when the clearing event arrives, the interface address will be
hence T/EC thinks it is a different device:
RG100BRA 10.22.0.2 Node up
I have included the response to two nslookup commands, the second
executed immediately after the first. As you can see, for each
command, we get a different IP address as the first interface in the
> nslookup RG100BRA
Addresses: 10.0.7.131, 10.22.0.2, 10.22.0.6, 10.170.0.1
10.171.0.1, 10.0.12.3, 10.0.4.189
> nslookup RG100BRA
Addresses: 10.22.0.2, 10.22.0.6, 10.170.0.1, 10.171.0.1
10.0.12.3, 10.0.4.189, 10.0.7.131
1. We would like to know if there is a way to 'force' NetView to use
a specific IP address as the primary IP address for the router,
without having to use the /etc/hosts file?
2. Has anyone implemented DNS, NetView and T/EC successfully?
3. Is there a Redbook which describes this type of implementation?
Any help will be greatly appreciated.
Julio W. Troya
Associate Technical Specialist
Enterprise Systems Management
Bank of Nova Scotia
Scarborough, Ontario, Canada
E-mail: julio_troya AT hotmail DOT com
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