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idata
Community Manager
3,617 Views

X710 SR-IOV VF still working when PF is down

Hi there,

I'm using X710-DA4 with SR-IOV mode on Skylake servers.

latest fw and drivers (i40e) installed on system. and vf driver is added into blacklist.

there is a VF that belongs to a PF. and that VF is attached to a VM.

after that, I tried ping from VM to a pc that connected to the server port that has the PF.

it works well. ping packets are received by the pc.

the problem (or different behavior) is that,

even the PF link goes down using "ifconfig xx down or ip link set xxx down" but the VF still sending packet to the pc.

is this right behavior on X710/XL710?

if yes, any architectural/tech background that I can get?

Regards,

0 Kudos
13 Replies
idata
Community Manager
799 Views

Hi Nasaram,

 

 

Thank you for posting in Wired Communities. Can you share the exact LInux operating system used? I will need to further check.

 

 

Thanks,

 

Sharon T
idata
Community Manager
799 Views

It's been tested on two different OS.

- CentOS 7.4

- hpelinux 4.4.21

Driver version was 2.4.3

idata
Community Manager
799 Views

Hi Nasaram,

 

 

Thank you for the information. I will further check.

 

 

Regards,

 

Sharon T
idata
Community Manager
799 Views

Hi Nasaram,

 

 

This is a normal behavior, you may refer to the SR-IOV primer at https://www.intel.com/content/dam/doc/application-note/pci-sig-sr-iov-primer-sr-iov-technology-paper... for additional details on how it works.

 

 

Once the SR-IOV is enabled, the VF will have its own dedicated resources within the IO device even the enabled VF is associated wit the PF function. That explain why the VF can still send packets. Please take note also that this also required kernel support mentioned in our README file. https://downloadmirror.intel.com/26001/eng/readme.txt

 

 

 

Thanks,

 

Sharon T
idata
Community Manager
799 Views

Hi Sharon,

Those documents are actually I have read already. and I can guess some of new features are related with this behavior. but no exact explanations on those documents and that is why I am asking this.

According to the datasheet for 82599, it has explained same things that you mentioned about resources allocation for VF. and it also mentioned about 'able to communication between VFs within NIC based on internal switch'. but no mention that VF can send packet to outside of NIC. that is common sense before. that is what the document 'SR-IOV primer' explain, it is traditional document one.

So is there any architectural comparison document for those two nic that include 'differences between Niantic and Fortville in SR-IOV mode' something like that?

idata
Community Manager
799 Views

Hi Nasaram,

 

 

Thank you for the reply. As mentioned once the VF is setup in the VM, "each VF has its own dedicated resources within the I/O device". So this enables a VF to send/receive data even if the physical function is down. So are you referring that you need documentation for X710 that explicitly explain the VF can send packet to the NIC even if the PF link is down?

 

 

Are these the reference information of 82599 you mentioned ?

 

https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/82599-10-gbe-controller-data...

 

 

https://www.intel.com/content/www/us/en/embedded/products/networking/82599-sr-iov-driver-companion-g...

 

 

Looking forward to your reply so that I can better assist on this.

 

 

Thanks,

 

Sharon T

 

idata
Community Manager
799 Views

Hi Sharon,

yes, I need a proof that

- once VF is setup in the VM, "each VF has its own dedicated resources within the I/O device". So this enables a VF to send/receive data to outside of NIC even if the physical function is down.

and I have read all those datasheet (82599/x710) and sr-iov guide.

Regards,

idata
Community Manager
799 Views

Hi Nasaram,

 

 

Thank you for the clarification. Will check on this.

 

 

Regards,

 

Sharon T
idata
Community Manager
799 Views

Hi Nasaram,

 

 

With regards to additional information, you may register at link below to gain access which required NDA.

 

https://www.intel.com/content/www/us/en/my-intel/sign-in.html

 

 

Hope the information help.

 

 

Regards,

 

Sharon T
idata
Community Manager
799 Views

Hi Sharon,

I have logged into the system. so what document should I search?

Regards,

idata
Community Manager
799 Views

Hi Nasaram,

 

 

You may search this datasheet "Intel Ethernet Controller 710 [Fortville] Series Datasheet".

 

 

Hope the information help.

 

 

Regards,

 

Sharon T
idata
Community Manager
799 Views

Hi Nasaram,

 

 

Please feel free to update me if further assistance needed.

 

 

Thanks,

 

Sharon T
CLiu39
Beginner
799 Views

Hi there,

I'm using X710 with SR-IOV mode and the VF is attached to a VM.

When the PF is down, I change the VF link state from enable to auto. The command is like this:

ip link set eth0 vf 1 state auto

after that, I logged in the VM and used 'ifconfig' finding the network interface is still running and the state is UP.

is this right behavior on X710/XL710,

Regards,

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