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Two NICS presented to OS, possible to only present one ?

paulregan
Level 1
Level 1

B200-M1 blades and Menlo CNA.

The SPs are using a dynamic vNIC templates with fabric A or B selected and F/O enabled.

What we're witnessing is the OS will always be presented with two NIC's.  Depending on which Fabric A/B the SP is set to determins which NIC is active. eg : In Linux eth0 & eth1 are detected.  If the SP points to A eth0 is active, and B then eth1 is active.

My question is : Using the Menlo card is it possible to present only one NIC to the OS and still retain f/o ?

We use a number of auto config tools and really want consistency on which NIC is active but also still want to use both A & B fabrics.  Rather than assigning all SP' to A.

Paul

4 Replies 4

Manish Tandon
Cisco Employee
Cisco Employee

Paul

With Menlo(E/Q) you cannot limit the presence of vNIC to 1.

If you look at the Menlo (M71KR) architecture, it is an intel oplin, a fc (qlogic or emulex) and a menlo (fcoe) chip.

http://www.cisco.com/en/US/prod/collateral/ps10265/ps10280/data_sheet_c78-524774.html

The Oplin and the fc chipset are seen as PCI devices to the OS (if you were to do lspci -v or ifconfig -a on linux for example) irrespective of what is there in your service profile.

The service profile (network section) in this case amongst other things like Qos/Pinning defines what MAC address you want it to have and the access port config (VLANs allowed etc) and not whether you can hide the PCI device from the OS.

With the M81KR (VIC) adapter, as the PCI devices are created as per the Service profile, yes, you control what the OS sees.

Thanks

--Manish

Hi Manish

Thanks for the reply .. its leads me to a second question, same topic:

If I cant 'hide' the second NIC is there a way to always use NIC 0 irrespective of which fabric [A/B] is chosen in the service profile ?

Regards

Paul

Paul

These are 2 static PCI devices (with device numbering) which the OS will show.

Default behavior with Menlo (linux terminology):

Lets say you don't create any vNICs in a SP and give it to a Menlo adapter based blade.

Your ifconfig should show eth0/eth1 while the link on both will be down (i.e unusable as the FI side config isn't done).

If you create 1 vNIC (side A), your eth0 will have link up with correct VLANs, eth1 down.

If you create 1 vNIC (side B), your eth1 will have link up with the correct VLAN, eth0 down.

It is for the way OS enumerates the devices. The first ethernet device is wired to side A.

You could potentially try changing the HWADDR/MACADDR in the /etc/sysconfig/network-scripts/ifcfg-eth[0-1] files to see if it works for you i.e assign an ip based on it.

With M81KR as I mentioned before you don't have this issue. You can call out the PCI order, number of devices and which vNIC goes to which side.

So 2 vNICs created in the M81KR could both be going to side A for example. This vNIC config will fail on a Menlo.

Is the use case that for a singly attached server, you are trying to do half the blades use Side A while the other Side B while maintaining uniformity in your imaging tools?

--Manish

Hi

"Is the use case that for a singly attached server, you are trying to do half the blades use Side A while the other Side B while maintaining uniformity in your imaging tools?"

Thats exactly it .. sounds like we cant with the blade/cna combo we have, which is fine .. we can work around it ..

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