Re: Multi-homed interface and Oracle listener

From: Jeff Traigle <traigle_at_si.umich.edu>
Date: Mon, 20 Jan 2003 00:03:02 -0500
Message-ID: <BA50ED36.3D351%traigle@si.umich.edu>

On 1/19/03 6:12 PM, in article b0fbdb$kcn$1_at_web1.cup.hp.com, "Rick Jones" <foo_at_bar.baz.invalid> wrote:

> In comp.sys.hp.hpux Jeff Traigle <traigle_at_si.umich.edu> wrote:

>> Normally, the Oracle listener must be configured to watch port 1521
>> on each IP address configured on a system (at least when the IP
>> addresses are assigned to different interfaces from previous
>> configurations with multi-NIC systems I set up, as best I can
>> recall). On this system, however, even though the listener
>> configuration wasn't changed, clients are still able to connect to
>> the database using the new IP address.

>

>> The only thing I can think of as to why this is working is the OS is
>> doing some transparent translation since the addresses are assigned
>> to the same interface. Would be nice to better understand the
>> dynamic that is allowing this to function. Anyone care to take a
>> stab at it?

>
> Since HP-UX (10.20 at least) has no support for NAT, it shouldn't be
> translating any IP addresses. Same NIC or not.
>
> I would check the output of netstat -an | grep 1521 and make sure that
> the Oracle listener isn't listening on INADDR_ANY (wildcard IP), or on
> both IPs. The other possibility is that the client config change
> didn't really "take" and they are still using the old IPs. That would
> appear in the netstat -an output.
>
> rick jones

Well, the listener.ora file appears to be only configured for the old IP address just as it always had been (actually the old fully qualified hostname to be completely accurate). I was going to configure it to listen to both addresses during the transition period, but that change was removed by someone else after I had it working (they panicked when the monitoring utilities showed things down and were mucking around after me), which is why I was amazed everything still worked.

As for the client config not taking, that definitely isn't the case. The clients are Win98 PCs and the fully qualified hostname was certainly changed from the old to the new in their tnsnames.ora files so they are definitely resolving to the new address on that end.

Will check out netstat tomorrow to see what that shows and get a copy of the listener.ora file for you so you can maybe spot something I'm missing that explains this.

-- 
Jeff Traigle
traigle_at_si.umich.edu
http://www-personal.si.umich.edu/~traigle/

Received on Sun Jan 19 2003 - 23:03:02 CST