Joel,
I filed your below response away knowing at sometime I'd refer back to it.
I'm in the process of building a NV5.1 system and there are several Cisco
routers in our network that have multiple paths to them. I was looking for
a way to associate one host name/IP address with a router such that via DNS
we'd always be able to telnet/ping/traceroute to that node and not have to
worry about a particular interface being down on a router. Assigning a
loopback address to the router seems to be the way to go to achieve that
capability.
I pre-configured DNS as you recommended below. That is, I assigned loopback
addresses to all routers and only put those names in DNS. However, as
Netview is discovering my network, it's mechanism is using the IP address of
the first interface it encounters for a particular router as it's label,
selection name, and IP hostname, etc. Furthermore, an "ovobjprint -s ..."
of that router doesn't even acknowledge the presence of the loopback
interface, as it's "TopM Interface Count" is 3 (two serial plus 1
token-ring).
So, my question to anybody out there is is there anyway that I can have
Netview recognize these loopback addresses? And, furthermore, would there
be a way of telling or fooling the discovery mechanism into picking the
loopback interface as it's main object in the database? Thanks for any
suggestions.
Mark S. Lucas
Employers Reinsurance Corp.
Networking Systems Specialist
(913) 676-5718 (direct)
(913) 676-5108 (fax)
Mark.Lucas@ercgroup.com
-----Original Message-----
From: Joel A. Gerber [mailto:joel.gerber@USAA.COM]
Sent: Tuesday, August 25, 1998 7:53 AM
To: NV-L@UCSBVM.UCSB.EDU
Subject: Re: NetView-T/EC-DNS Implementation Problem... HELP!
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).
-----Original Message-----
From: Julio W. Troya [SMTP:julio_troya@HOTMAIL.COM]
Sent: Monday, August 24, 1998 15:50
To: NV-L@UCSBVM.UCSB.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
cannot solve.
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
"round-robin"
fashion.
Because we get a different IP address for each event, T/EC is unable
to
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
different, and
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
router.
> nslookup RG100BRA
Server: localhost.bns
Address: 127.0.0.1
Name: RG100BRA.corp.bns
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
Server: localhost.bns
Address: 127.0.0.1
Name: RG100BRA.corp.bns
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
Tel: 416-701-7144
Fax: 416-288-4400
E-mail: julio_troya@hotmail.com
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