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New Member

OUI for WWN and MACs

When I create pools of wwn and macs for a service profile template, is there a block of addresses that start with an OUI that are specific to UCS?  In this guide: http://www.ciscosystems.sc/en/US/products/ps10281/products_configuration_example09186a0080af7515.shtml, I can see the a tip in the window of this picture: http://www.cisco.com/image/gif/paws/110297/create-sp-ucsblade-11.gif that specifies using a prefix of 20:00:00:25:B5:xx:xx:xx will ensure uniquiness in the WWN names but when I'm at the same screen on our UCS, I don't see this tip.  The same goes for the MACs, is there a block with certain values I should start with?  The MAC section of the guide shows 02:25:B5:00:00:00 in the configuration window: http://www.cisco.com/image/gif/paws/110297/create-sp-ucsblade-09.gif but is this unique to UCS?

Thanks.

1 ACCEPTED SOLUTION

Accepted Solutions

Re: OUI for WWN and MACs

For MACs Cisco has registered the OUI 00:25:b5 the last three octets are up to you. You can either make up some arbitrary numbers or you can put some logic behind it. Here is what I recommend for MACs.

  • Create two MAC pools; one for Fabric A and one for Fabric B
  • For the last three octets use the first one for the site/cluster and the next for the fabric A or B. For example site 1, cluster 1 and Fabric A would be this 00:25:b5:11:a0:00 and go up from there. Fabric B would be this 00:25:b5:11:b0:00 and cluster 2 would be this 00:25:b5:12:a0:00.

For the WWNNs and WWPNs you will want three pools; one for the node WWN and two for the port (vHBA) WWN.

Same concept here for the WWNNs use something like 20:11:00:25:b5:00:00:00 for site 1 cluster 1 and 20:12:00:25:B5:00:00:00 for site 1 cluster 2.

For the WWPN pools do one for Fabric A and one for Fabric B like this

  • Fabric A site 1 cluster 1 - 20:00:00:25:b5:11:aa:00
  • Fabric B site 1 cluster 1 - 20:00:00:25:b5:11:bb:00

By creating MAC and WWPN pools for each Fabric you can easily identify which Fabric a MAC or WWN is coming from when looking the MAC table on a switch or when zoning you can easily pick out WWNs. Could be useful when troubleshooting as well.

12 REPLIES

Re: OUI for WWN and MACs

For MACs Cisco has registered the OUI 00:25:b5 the last three octets are up to you. You can either make up some arbitrary numbers or you can put some logic behind it. Here is what I recommend for MACs.

  • Create two MAC pools; one for Fabric A and one for Fabric B
  • For the last three octets use the first one for the site/cluster and the next for the fabric A or B. For example site 1, cluster 1 and Fabric A would be this 00:25:b5:11:a0:00 and go up from there. Fabric B would be this 00:25:b5:11:b0:00 and cluster 2 would be this 00:25:b5:12:a0:00.

For the WWNNs and WWPNs you will want three pools; one for the node WWN and two for the port (vHBA) WWN.

Same concept here for the WWNNs use something like 20:11:00:25:b5:00:00:00 for site 1 cluster 1 and 20:12:00:25:B5:00:00:00 for site 1 cluster 2.

For the WWPN pools do one for Fabric A and one for Fabric B like this

  • Fabric A site 1 cluster 1 - 20:00:00:25:b5:11:aa:00
  • Fabric B site 1 cluster 1 - 20:00:00:25:b5:11:bb:00

By creating MAC and WWPN pools for each Fabric you can easily identify which Fabric a MAC or WWN is coming from when looking the MAC table on a switch or when zoning you can easily pick out WWNs. Could be useful when troubleshooting as well.

New Member

Re: OUI for WWN and MACs

Thanks for the detailed response Jeremy!

New Member

OUI for WWN and MACs

The answer given does not really answer the question:

"...is there a block of addresses that start with an OUI that are specific to UCS?"

In other words, is the Cisco-owned block, 00:25:B5, used exclusively by UCS products? When using these addresses in UCS, does the customer need to worry that adjacent (non-UCS) switches might use the same Cisco-owned OUI, or is this OUI reserved exclusively for UCS?

Re: OUI for WWN and MACs

Hi and welcome to the community,

The answer is here in the same configuration guide...

http://www.cisco.com/c/en/us/td/docs/unified_computing/ucs/sw/gui/config/guide/2-1/b_UCSM_GUI_Configuration_Guide_2_1/b_UCSM_GUI_Configuration_Guide_2_1_chapter_010011.html

"A MAC pool is a collection of network identities, or MAC addresses, that are unique in their layer 2 environment and are available to be  assigned to vNICs on a server."

Bottom line.. 00:25:b5 is owned by Cisco, but the MAC addresses are going to be unique for that layer 2 domain.

Rate ALL helpful answers.

-Kenny

New Member

Re: OUI for WWN and MACs

Hi Kenny,

Thanks for responding, but this still does not answer the question. The question is:

Is the 00:25:b5 range reserved exclusively for UCS, or is there a chance that some non-UCS devices may have addresses in that range? This is important to know. If this range is UCS-only, then a customer can safely use this range for their VNICs, and not worry about having a MAC conflict with adjacent Cisco switches.

The page that you linked me to in the configuration guide does have any information about this topic, although that is where one would expect this information to be found. (I have been told, and have seen it somewhere in print in the past, that this range is UCS-only, but now I am trying to verify it, and have not found the MAC address rules in the configuration guide.)

Thank you.

VIP Green

Re: OUI for WWN and MACs

....Is the 00:25:b5 range reserved exclusively for UCS, or is there a chance that some non-UCS devices may have addresses in that range?....

NO ! customer is responsible to configure unique MAC range for every UCS domain, very important if you have >1 UCS domain on same L2 domain.

New Member

Re: OUI for WWN and MACs

Thank you wdey. Of course that is the case. But again, that is not the question that is being asked. The question is this:

Does Cisco use the 00:25:b5 range for any non-UCS products, or is this range specifically reserved as UCS-only? That was the orginal poster's question, and I also repeated the question in my above posts.

VIP Green

OUI for WWN and MACs

00:25:b5 prefix is used by Cisco, in general, not dedicated to UCS !

Re: OUI for WWN and MACs

That OUI is for Cisco in general, the rest is just too much space to dedicate it only to UCS... We expect a good amount of servers to sold but it is just to much considering that, as explained in the "answer" for this post, you can make some variations to give them some sort of sense.

-Kenny

New Member

OUI for WWN and MACs

Thank you wdey and Kenny, that answers the question.

So, if a customer assigns MAC addresses to VNICs, using the 00:25:B5 range, there is a chance that there could be a MAC address conflict, if an adjacent Cisco switch in the same L2 domain has a burnt-in MAC in that same range?

OUI for WWN and MACs

Correct

-Kenny

New Member

OUI for WWN and MACs

Thank you for clarifying that.

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