Duplicate MAC Addresses?

Hi Folks,
Has anyone experienced duplicate MAC addresss issues with the UCS-B/6120 connected to a 6500? I'm seeing the following on my 6500:
6506#sh arp | inc 0025
Internet 10.1.79.60             0   0025.b501.0005 ARPA   Vlan210
Internet 10.1.79.62             4   0025.b501.0007 ARPA   Vlan210
Internet 10.1.79.98            51   0025.b501.0005 ARPA   Vlan210
I checked my profiles and they appear to each have a uniquely assigned MAC address.   The correct entry is 10.1.79.60 and the 6120 should be replying with 0025.b501.006 for 10.1.79.98.
Anyone got any thoughts on how to correct this issue?
Take Care
Jason

There is nothing wrong with what you're seeing. It's acceptable to have N IP addresses resolve to 1 MAC
address. That is the case with secondary IP addresses for instance, Proxy-ARPing, "plumb" interfaces, etc.

Similar Messages

WGM - Can't add computers due to duplicate MAC address

Hello all,
I'm having a problem with 10.5.4 Server where once a computer is deleted from WGM it can't be added back. WGM gives an error message about duplicate MAC addresses. It appears that, although the deleted computer is no longer listed, the MAC address and name seem to still either be cached or in the database.
Any ideas?
Thanks

Saw you have no replies yet... did you ever get this issue figured out?
It's a shot in the dark, but years back we used to get zombie Macs (er, MACs) that would not show up in the list of computers, but were "still in the system" as a damaged record. Try enabling the "All Records" tab from the WGM prefs and searching for the computer record there, within the "Computers" list. If you can find them, deleting them should allow you to add them back in normally.
Let us know. Cheers, Joel

Duplicate MAC Addresses effect

Hi All,
I have a query regarding the entry of duplicate MAC entries in switch. I tried issuing the following command:-
Switch(config)#mac address-table static 0007.e9f6.4fd2 vlan 1 interface fa0/2
Switch(config)#mac address-table static 0007.e9f6.4fd2 vlan 1 interface fa0/3
And after issuing the command, the resultant MAC table was as follows:-
1 0007.e9f6.4fd1 STATIC Fa0/2 Fa0/3
What does this signify. Where would a packet destined to this MAC address reach (I mean the port that it will reach)
Does it mean that there could be Network Load Balancing?
Thanks,
Sridhar.

HI
It will reach to the port where the end system is connected.u just deifined the mac-address as static on two ports u will not connect the end system to two ports so on the port which u r end system will connected will be up/up and on the port which the end system is not connected it will be in down state.hope i am correct in this if not plz correct me.
Thanks
Mahmood

Duplicate MAC addresses on touch panels

I have 2 TPC 2012 touch panels (out of 15) with the same MAC address. Of course since the MAC address is the same, this causes network problems such as duplicate DHCP assigned IP addresses.
How can this happen?
How do I fix it?
Message Edited by dbtestcon on 09-18-2008 02:46 PM

Hello,
Before we go any further, I need to confirm that the MAC addresses are really the same. I need you to submit a screenshot of the two addresses.
Can you type ipconfig/all in your command prompt. Take a screen shot of the Physical Address. Also, go to control panel > network connections > local area connection. Right-click and go to Properties. Left-click on Configure. Take a screenshot of the Advanced Tab as well. Post those and we'll go from there.
National Instruments
Applications Engineer

Thinkcentre Edge M-Series with duplicate mac address

We have a lot of Edge M-Series all with the same MAC address appears in Bios (F1), using Windows 8.1 perhaps need to modify media access control with custome address, it's there an Bios update available or any issue to fix this ?

Have you updated to the latest BIOS?
If so, then: In device manager/network adapters, check the intel ethernet device, under the advanced tab, the ability to set the locally admin address (MAC.)

Duplicate MAC Address on HP 8530p

Hi all
We just have figured out, that we have more then one HP Elitebook 8530p with the same MAC address. Special is, that the MAC address is in a unusual range. It has the number 88:88:88:88:87:88. There are more then one notebook that has the same MAC. We have updated the BIOS to the latest available, but without a solution. Also in the BIOS there is no way to change it physical.
We need a unique MAC because we do deploy the OS with PXE in SCCM and therfore it must be unique.
Any hint what we can do in this manner?
Kind regards, Stefan

Print a Wireless Network Test.
I hope you are not using this for MAC filtering on your router. It is pretty much a useless security method.
Read more here.
Say thanks by clicking "Kudos" "thumbs up" in the post that helped you.
I am employed by HP

ISG session with duplicate mac addresses - ASR 1k

Hello all,
I have an issue with current ISG implementation on ASR 1k.
We have subset of subscribers that are authenticated based on their mac address and another subset that are authenticated based on their c-vlan/s-vlan tag which is derived from nas-port-id. If two subscribers have identical mac addresses and one is authed based on mac and the other is based on c-vlan/s-vlan, the last one to auth kicks the previous authenticated session and takes it's place, which is totaly unacceptable.
For subscribers with mac based auth, session initiatior is unclassified mac address, as for c-vlan/s-vlan based auth it is dhcp request.
Forgive the lack of details, if anything I am ready to supply any available and open info. Personaly I think this is just shortcoming of ASR 1k s ISG implementation, because I know for a fact that 9K BNG handles this situation very well and has a more precise definition of c-vlan/s-vlan than 1k.
Any ideas on how to tackle this?

Hi,
Not sure if it would be possible since mac address is probably being used as a session key for both sessions (that's why the latest subscriber to come up, takes over the first one) even if you are using different identifiers (mac-address vs c-vlan/s-vlan).
Are these L2 subscribers or routed subscribers?
Could you provide a configuration of the ISG?
Regards.

Duplicate MACS

When I run the duplicate MAC report from CM the report shows over 2,500 duplicate MAC addresses on our network.
I'm sure this isn't correct as the MACs that are showing as duplicates show twice on the same port (once on the voice vlan and once on the native vlan)
Is this a bug? Is there a way to fix this? I've attached an example from the report.

Hi Joe,
I've looked into this a bit further today and can now confirm that 99% of the reported duplicates are infact IP Phones. There are a few of PC's and Servers reported as duplicates but these can be explained (ie, clustered servers, etc). I'm still not sure why the IP Phones are being reported as duplicated though?
When I do a "show mac address table int fa0/xx" on a switch I get the output below.
Vlan    Mac Address       Type           Ports
109    000b.fd5d.f173    DYNAMIC     Fa0/14
217    000b.fd5d.f173    DYNAMIC     Fa0/14
000b.fd5d.f173 is an IP Phone
VLAN 109 is the data VLAN
VLAN 217 is the Voice VLAN
Is there away that I can prevent these appearing as duplicates so the report can be more accurate?

RSPAN limitations with vtp domain on 6500- 12.2.3(33)SXH5 ERROR DUPLICATED MAC ADDRESS ON TWO VLANS

Hello everyone,
i have a network with a
L3(core) 6500 12.2.3(33)SXH5 with vtp (server) and pruning on, rstp
L2(distribution, ) with 3750 fiber connected
L2(access) with mixed hardware 2950-3750
when i go to setup a rspan:
6500(config)#vlan 400
6500(config-vlan)#remote-span
access(config)#monitor session1 source remote vlan400
access(config)#monitor session1 destination fa2/0/1
access(config)#monitor session1 source int gi1/0/37, gi1/0/44, tx
access(config)#monitor session1 destination remote vlan 400
my problem is on a periferic access switches 2950 not redundant:
i relevated a
duplicate mac-address table, i found a every mac on 2 vlan, the 200 and 400(of remote span) with related problem of loss of packets and random connection problem
My question is:
is compatibile the rspan with 6500 vtp, how i can fixed this problems?
thank you

Other users from the forums with a similar problem came to a conflict occurring here
Oct 18 11:52:41 MacBook-Pro opendirectoryd[123]: 2595.39 - ODNodeCreateWithNameAndOptions failed with error 'Unknown node name' (2000)
They say it's some sort of conflict with the language of the installation or is it language keyboard input, then what is meant and how it can be solved I do not understand if this is certainly so.
(sorry for my bad english)

Same device name has multiple IPs and MAC addresses - my fix

Router: Cisco Linksys EA4500 (N900)
Cloud Firmware: 2.1.139.145204 (no, I don't plan to update this version to the latest)
Cable Modem Service
So I was playing around with Oracle's VirtualBox (it's kinda like VMware, or Microsoft's HyperV) on my primary LAN-wired desktop in my home network, to create Virtual Machines (VMs, hereafter) to technically preview Microsoft's Windows 10 (may be released next year), and a couple of my other Windows installations.
I ended up launching VMs with the same hostname, but with different MAC addresses (and thus, different IP addresses).
The Linksys cloud firmware displayed all those MAC-IP combinations under the same hostname icon in its Smart WiFi Tools' Device List.
Some people here have complained about this issue, and I'd like to say this has never happened to me before (using the EA4500 for over a year), and I have about 15 devices connecting to my router, a minimum of 5 online at any one time.
With this kind of situation, you can't individually address each of those affected machines for Parental Controls and other configuration options.
What I did to solve the problem:
1. Ensure every VM has a unique name (change hostname in Windows Control Panel).
(this can be challenging since a cloned VM will initially start with the same name as its master, and the problem will already occur. Once the problem occurs, just renaming the hostname and rebooting the device/VM will not solve the problem. Would be nice if it did)
2. Get all duplicated devices off the network.
3. Execute a "ipconfig /flushdns" from the command prompt.
4. Delete any device (click on the x in the Device List icon) when it goes offline in the Smart WiFi Device List.
5. Ensure no duplicates exist under Connectivity, Local Network, DHCP Reservations (I use DHCP reservation for a number of my devices so they are guaranteed a fixed local IP)
6. Hit Refresh (more than once! ) under Troubleshooting, Status to get a list of devices with non-duplicate MAC addresses.
7. Do the same after clicking on the DHCP client table button on the same page.
8. Reboot the router (this step was not necessary some times, but I'd do it just to be safe).
9. Now add the devices back onto your network one at a time.
If there are no more hostname duplications, the VM devices with their unique MAC addresses should create new icons in the Device List page as they connect to the home network.
Hope the above helps somebody.

For which version of Mail and OS?

FWSM - Duplicated MAC Addresses across contexts

I have two 7609S routers each with a FWSM running 4.0( 8)
I am licensed for 20 contexts.
Recently, I added a context for a new application and required access to a VLAN that already had an interface in another context.
The MAC address assigned to the interface in the new context was assigned the same MAC address as the interface in the previous context.
This caused an application running through the first context to fail.
I know that on the FWSM I cannot hardcode a MAC address to an interface in a context so how do I get around this problem caused by the duplicate MAC addresses?
Thanks, Ted

Hi Ted,
The short answer is that you'll need to add static NAT statements (identity NAT is fine) to both contexts for each of the destinations that live behind each context.
For example, assume you share the outside interface across both of the following contexts:
ContextA - protects hosts in the 10.1.1.0/24 inside subnet
ContextB - protects hosts in the 10.2.2.0/24 inside subnet
You would need to add the following statics:
ContextA:
static (inside,outside) 10.1.1.0 10.1.1.0 netmask 255.255.255.0
ContextB:
static (inside,outside) 10.2.2.0 10.2.2.0 netmask 255.255.255.0
See the following guide for more details:
http://www.cisco.com/en/US/docs/security/fwsm/fwsm40/configuration/guide/contxt_f.html#wp1124236
-Mike

How do I move/copy contacts from Entourage to iCloud Address Book without creating duplicates? Address Book on Mac, iCloud, iPhone and iPad is now empty

How do I move/copy contacts from Entourage to iCloud Address Book without creating duplicates? Address Book on Mac, iCloud, iPhone and iPad is now empty

Thank you for letting me know!
Going to give it a go. Had a back up of all my clients files stupidly not my software as I have the originals disks. Just realised that amongst the software is ibiz and have lost al my accounting and billing files for the last 7 years want to cry so losing my contacts now will really tip me over the edge!
Fingerscrossed this works!

SCOM Network Discovery - Duplicate nodes with different Device Keys (MAC address)

Hi There,
We have deplyed SCOM 2012 SP1 for server and network monitoring. In the "Network Devices" view, there are few duplicate node entries for the same device. When i look at the details of each entry, the device keys (MAC address) are
different. for example, if there are 3 entires for the same device, only one will have the correct MAC address and remaining 2 are incorrect.
Have anyone came across such issue? Any solution to avoid the duplicates?
Thanks.
Venu.
Best regards, Venu.

Last Thursday (9/25/14), Microsoft provided me with an updated version of a file that is used as part of the discovery process. At first, it appeared to only resolve the issue for some devices which was disappointing. On Saturday, I decided
to remove all managed devices and rediscover everything from scratch. We have 237 devices to monitor. Since Saturday, I had one ICMP only device duplicate itself, but after I removed the duplicate, I have not had any other duplicates created and
there have been many rediscoveries ru nsince then. So far so good. I've asked Microsoft to keep the case open until next Monday. This weekend, I have a full discovery scheduled to run on a schedule. I'll feel good after that if there
are still no duplicates.
The file replaced is "ic-iftable.asl" which is located on each management server in the path ""\[ SCOM install directory]\Server\NetworkMonitoring\rules\discovery". I'm not sure if I'm allowed to share the updated version of
the file. I have not received an explanation from the support technician yet as to the root cause. They took at least 5 sets of trace logs during the discovery and subsequent rediscovery process before giving me this updated file. I'll let
you know.

HSRP - Duplicate address on Vlan, sourced by mac-address

Hi ,
Network structure
Switch A --- Customer firewall 1
|
Switch B --- Customer firewall2
May be some one can help me.
There was a nagious alert yesterday and on investigation I found the 'Duplicate address x.x.x.x(VIP) on Vlanxxx, sourced by 0006.b19c.c5d9' error
It a HA feed from our switches which is going to customer firewalls.
On further investigation I have found on our switch A the ARP table is not learning the VIP address from this mac-address where as on switch B is learning the VIP address through mac 0006.b10c.c8d9 which is customer sonic firewall which is not a normal behaviour.
Our switches are Cisco 3560 switch.
Please if you could let me know what causing this.

Hi mcgowan,
Yes, there is duplicate MAC. But, its duplicate between interface vlan address and virtual MAC address on HSRP.
when I type command :
show mac address | i 0000.0c07.ac01
It shows me :
100 0000.0c07.ac01 STATIC CPU
I think this MAC generate by system on HSRP. Currently I shutdown interface vlan 100 on switch A, like as your suggestion. But the impact is my client will get trouble when switch B is down, because HSRP is not running well.
Regards,
Rakhmad

ICloud to Mac Address Book - Two Questions

Okay, I have learned/accepted that iCloud is not the sync'ing deal that MobileMe was (missed that in the fine print as I have been a loyal .mac user from its inception and like the MM syncing). I understand that everything is updated in the cloud and pushed to various devices (for me, iPhone 4S, new iPad and 2009 MBP). So, how is it possible for my iCloud address book to have more contacts than my MBP address book? Wouldn't all of the ones in iCloud be pushed to the MBP? The only thing I can think is that before I understood the concept that there are two address books resident on the MBP, I starting deleting what I thought were duplicates since I wasn't able to merge them due to two different sources. I could not find a way at that time to tell me which line was from what source. Then, once I get the two address books matching - mostly to ensure that I am not missing anything in the iCloud one - what purpose does the Mac based address book serve? I just had a nightmare of dragging various cards from my iCloud address page on the right into the iCloud group on the left and only to realize after doing at least 20 cards that after the first one, the left page registers back up putting the Mac based group across from the iCloud contact list so I dropped many of them into the Mac group instead of the iCloud group. The iCal doesn't maintain a Mac version and an iCloud version, why does the address book? BTW, all software on all devices is up to date as of this posting.

Please pardon what may be a silly question. This is my first ever post...
I was thinking about deleting "On My Mac" address book per your above instructions, and sticking with the one iCloud contacts. The problem I am afraid of running into is this: In iTunes, when I sync contacts, the groups that show available for syncing all come from "On My Mac". If I delete from the Mac, will that make my "Contacts" icon on my iPad 'dead'? Thereby, forcing me to log onto iCloud to view my Contacts, instead of a handy shortcut???
Or will I simply get to forgo the iTunes syncing... and the "contacts" icon on my iPad will reflect what was synced thru iCloud?
If the latter is true, does that simply mean I will need to recreate my "groups" in iCloud?
Thanks in advance, I certainly need some guidance.

Duplicate MAC Addresses?

Similar Messages

Maybe you are looking for