Anonymous_User Absent Member.
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conflict for IP address

Hello, and many thanks in advance for any advice you might have.

I adminster small, two node, deparmental server cluster on a large
university LAN. Our servers are running Netware 6.0 SP5. I am getting the
following error message:

7-17-2006 11:27:20 am: TCPIP-6.10-78
Severity = 1
This Server and the system having hardware address 00-02-B3-ED-CF-6B have
conflict for IP address 128.59.xxx.xxx.

where the hardware address listed is the server's own NIC. The IP address
hand entered into the server's config file.

This has happened intermittently for several months and I asked for help in
March on this forum. I was advised that it probably indicates that the
Spanning Tree Protocol was disabled on the switch. Then I stopped seeing the
error message.

Before I go any farther, is this a potentially serious issue? If it is just
cosmetic I'll live with it. (The only problem that seems it might be related
is sometimes a PC may take overly long to login on the cluster,
occassionally to the point of timing out and having to restart.)

When I noticed the error was back yesterday, I contacted our network
infrastructure group and asked them to check the switch. They confirmed that
STP is enabled on the switch and the two ports that our machines are
connected to are in a Spanning Tree Protocol forwarding state.

It doesn't seem to matter which server is the primary at the time. Our
preferred server went down last week due to a CPU hog and the other took
over without a flaw, but the IP conflict error popped up within a few
minutes on that server.

I also looked at TID10016507 but it says this frequently an issue with the
switch being set to Full Duplex and the server to Half Duplex. Our servers'
NICs are set to Full Duplex.


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12 Replies
Anonymous_User Absent Member.
Absent Member.

Re: conflict for IP address

You should have Auto/Auto at both ends (switch port &
server NIC) and see if that helps.

You mentioned about having 2 ports on the switch, so
it means you have 2 NICs on the server ? Are you teaming
for LB/FT on those 2 NICs ? If so, your networking guys
need to configure etherchanneling on the switch else you
will experience HostFlapping between the 2 switch ports.

Each port will announce the exact same MAC address via
different exit interface. This can create connectivity problems.

Don't ever disable Spanning Tree on a switch, it's there to
protect these kind of loops.


--
Edison Ortiz
Novell Product Support Forum SysOp
(No Email Support, Thanks !)
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Anonymous_User Absent Member.
Absent Member.

Re: conflict for IP address

Edison,

Thanks.

The two ports I mentioned are for one NIC in each node in the cluster.

Mike K


"Edison Ortiz" <eortiz@nscsysop.com> wrote in message
news:xn0eovhkie3ury000@support-forums.novell.com...
> You should have Auto/Auto at both ends (switch port &
> server NIC) and see if that helps.
>
> You mentioned about having 2 ports on the switch, so
> it means you have 2 NICs on the server ? Are you teaming
> for LB/FT on those 2 NICs ? If so, your networking guys
> need to configure etherchanneling on the switch else you
> will experience HostFlapping between the 2 switch ports.
>
> Each port will announce the exact same MAC address via
> different exit interface. This can create connectivity problems.
>
> Don't ever disable Spanning Tree on a switch, it's there to
> protect these kind of loops.
>
>
> --
> Edison Ortiz
> Novell Product Support Forum SysOp
> (No Email Support, Thanks !)



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Anonymous_User Absent Member.
Absent Member.

Re: conflict for IP address

On 7/18/2006 Mike Knoerzer wrote:

> Edison,
>
> Thanks.
>
> The two ports I mentioned are for one NIC in each node in the cluster.
>
> Mike K


The cluster may be advertising an unique MAC address back to the
switch inserted on different ports. You need etherchanneling configured
at the switch.


--
Edison Ortiz
Novell Product Support Forum SysOp
(No Email Support, Thanks !)
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Anonymous_User Absent Member.
Absent Member.

Re: conflict for IP address

Edison,

Edison Ortiz wrote:
>
> The cluster may be advertising an unique MAC address back to the
> switch inserted on different ports.


No, it doesn't.

CU,
--
Massimo Rosen
Novell Product Support Forum Sysop
No emails please!
http://www.cfc-it.de
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Anonymous_User Absent Member.
Absent Member.

Re: conflict for IP address

On 7/18/2006 Massimo Rosen wrote:

> No, it doesn't.


The only way to find out for sure is to check the CAM table
at the switch.

--
Edison Ortiz
Novell Product Support Forum SysOp
(No Email Support, Thanks !)
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Anonymous_User Absent Member.
Absent Member.

Re: conflict for IP address

Edison,

Edison Ortiz wrote:
>
> On 7/18/2006 Massimo Rosen wrote:
>
> > No, it doesn't.

>
> The only way to find out for sure is to check the CAM table
> at the switch.


Well, the switch might have a corrupt table. At any rate, in each case
I've seen this error, it *was* the switch at fault. And a Netware
cluster simply cannot present this very MAC he posted on seperate nodes,
unless the nics are broken, and actually *do* genuinely have the same
MAC address (which I *have* seen before, but only once in 15 years in
this business).

CU,
--
Massimo Rosen
Novell Support Connection Sysop
No emails please!
http://www.cfc-it.de
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Anonymous_User Absent Member.
Absent Member.

Re: conflict for IP address

Hello everyone, and thanks again,

I checked the system error logs on both nodes and it is not the case that
the two nodes are presenting the same MAC.

Two weeks ago our preferred node went down. Comparing the logs I found that
whichever node was running the Master IP Address resource, gets the conflict
error message for its own IP address with "the system having" the servers
own hardware address...and the MAC addresses listed are different. One is
00-02-B3-ED-CF-6B. The other is 00-06-5B-05-AC-E2.





"Massimo Rosen" <mrosenno@spamcfc-it.de> wrote in message
news:44BE3749.BA74CD8@spamcfc-it.de...
> Edison,
>
> Edison Ortiz wrote:
> >
> > On 7/18/2006 Massimo Rosen wrote:
> >
> > > No, it doesn't.

> >
> > The only way to find out for sure is to check the CAM table
> > at the switch.

>
> Well, the switch might have a corrupt table. At any rate, in each case
> I've seen this error, it *was* the switch at fault. And a Netware
> cluster simply cannot present this very MAC he posted on seperate nodes,
> unless the nics are broken, and actually *do* genuinely have the same
> MAC address (which I *have* seen before, but only once in 15 years in
> this business).
>
> CU,
> --
> Massimo Rosen
> Novell Support Connection Sysop
> No emails please!
> http://www.cfc-it.de



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Anonymous_User Absent Member.
Absent Member.

Re: conflict for IP address

On 7/24/2006 Mike Knoerzer wrote:

> One is
> 00-02-B3-ED-CF-6B. The other is 00-06-5B-05-AC-E2.


Ok, your switch may be faulty or misconfigured. Did you
enable portfast on the port where these 2 servers are
connected ?

Are your forcing the speed/duplex on both ends of the
connection or using auto/auto ?

On the server side, have you tried updating the NIC driver ?

Any input/output errors listed on the switch port interface ?


--
Edison Ortiz
Novell Product Support Forum SysOp
(No Email Support, Thanks !)
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Anonymous_User Absent Member.
Absent Member.

Re: conflict for IP address

Edison,

Our Network Operations group guy just got back to me. He said there are
Runts errors and Alignment errors on the ports. So he is referring me to the
group that handles the jacks and cables.


These points are probably moot, but for what it's worth, Portfast is enabled
on the ports and the switch is running auto speed/duplexing and is
successfully negotiating at 100MB/full. I checked INETCFG "View
Configuration" the line loading the NIC driver includes speed=0 and
forceduplex=0 (auto, think).

Thanks again.

Mike


"Edison Ortiz" <eortiz@nscsysop.com> wrote in message
news:xn0ep3rxg7fv3c003@support-forums.novell.com...
> On 7/24/2006 Mike Knoerzer wrote:
>
> > One is
> > 00-02-B3-ED-CF-6B. The other is 00-06-5B-05-AC-E2.

>
> Ok, your switch may be faulty or misconfigured. Did you
> enable portfast on the port where these 2 servers are
> connected ?
>
> Are your forcing the speed/duplex on both ends of the
> connection or using auto/auto ?
>
> On the server side, have you tried updating the NIC driver ?
>
> Any input/output errors listed on the switch port interface ?
>
>
> --
> Edison Ortiz
> Novell Product Support Forum SysOp
> (No Email Support, Thanks !)



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Anonymous_User Absent Member.
Absent Member.

Re: conflict for IP address

On 7/24/2006 Mike Knoerzer wrote:

> He said there are
> Runts errors and Alignment errors on the ports.


Which are usually sign of duplex mismatch but since you are
running auto/auto at both ends you may have bad cables or
a faulty port.


--
Edison Ortiz
Novell Product Support Forum SysOp
(No Email Support, Thanks !)
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Anonymous_User Absent Member.
Absent Member.

Re: conflict for IP address

Hello again.

One of our network cable tech group people checked the cables and jacks and
said all were "good," but the same guy also said that the communication with
the switch was obviously slow...even their test equipment took longer than
expected to get an IP addresss from the DHCP server.

In the meantime, I am still seeing one or two IP address conflict errors
every day or two. And when the conflict is occuring accessing files is very
slow and you can't log in. For some reason the errors seem to occur mostly
late at night. I have had only two incidents in the last month where people
have had to wait several minutes to login because the error occurred around
9:00 AM on those particular days.

I thought of resetting the NICs to manual 100 mbps/full duplex, mostly for
lack of anything else to test. But both are negotiating at 100/full now,
and they changed the ports on the switch already with no change. So I'm not
sure what I would be trying to show.

I guess I may just have to live with it as it is.

Thanks again for all your time and consideration.

Mike

"Edison Ortiz" <eortiz@nscsysop.com> wrote in message
news:xn0ep53822o82b001@support-forums.novell.com...
> On 7/24/2006 Mike Knoerzer wrote:
>
> > He said there are
> > Runts errors and Alignment errors on the ports.

>
> Which are usually sign of duplex mismatch but since you are
> running auto/auto at both ends you may have bad cables or
> a faulty port.
>
>
> --
> Edison Ortiz
> Novell Product Support Forum SysOp
> (No Email Support, Thanks !)



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Anonymous_User Absent Member.
Absent Member.

Re: conflict for IP address

On 8/1/2006 Mike Knoerzer wrote:

> So I'm not
> sure what I would be trying to show.


SPAN the server port to a monitor port and download a packet analyzer
(http://www.wireshark.org). You will need to work with the switching people
to get this setup.


--
Edison Ortiz
Novell Product Support Forum SysOp
(No Email Support, Thanks !)
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