UCS/Nexus and FCoE Question

[visitor68]

Hi, All:

Can one connect an FCoE target directly to a Fabric Interconnect or a Nexus 5xxx FCF when in NPV mode and not connected to an FC switch for fabric services and still be able to have the initiator see the target and be able to provision storage accordingly?

So, the scenario would be the following:

a rack server with a CNA connected to a Nexus 5xxx FCF in NPV mode

OR

a blade server with a CNA connected to a UCS Fabric Interconnect (which is also an FCF) in NPV mode

AND

In either of the cases above, there is NO CONNECTION between the FCF and an FC switch.

Will I be able to have the CNA (FCoE initiator) see the Strorage array (FCoE target)?

Thank you

[gkumark]

Hi,

Yes, you can connect the FCoE storage port directly to Fabric Interconnect(FI), but not when the FI is in end host or npv mode. You basically need to define the port connecting to FCoE storage as "FCoE Storage" port in UCS FI. For this to be done, you need to have the FI in FC Switch mode.

With respect to rack server, you can connect the CNA to a 10G port in N5K and configure the VFC there.

-Ganesh

[visitor68]

Ganesh, your answers make sense, and given my understanding of FCoE and the FLOGI and PLOGI processes, I want to agree with you. BUT I have had a person who I believe to be very knowledgeable in UCS (former Cisco solutions engineer) tell me that you CAN connect an FCoE storage array directly to an FI FCoE port while the FI is in NPV mode and be able to provision storage, even if the FI is not connected to an FC switch. To me, that doesnt make sense because, in such a case, there is no appliance to provide FC services to support the FIP FLOGI and PLOGI processes - and therefore, how would an E_Node (VN_Port) be able to log into the fabric, get an FC-ID and FPMA, register with the name server and engage in peer VN_Port capability discovery? How would a server CNA even know that there is a storage array that is reachable without the PLOGI process?

[visitor68]

Ganesh? Anyone?

Thanks

[gkumark · Accepted solution]

Hi,

Yes you are right. For the direct attached storage to work, you need the FI in FC switch mode. Your explanation is right and you cannot have direct attached storage in FC End host mode/npv mode. With FI in npv mode, it can just forward the FC requests to a NPIV switch and cannot process any FC requests like FLOGI etc..

Also, in UCS versions below 2.1 you would need a SAN switch connected to a FI running in switch mode and storage directly connected to it, which can push zoning database to the FI. Thanks to 2.1, you can have direct attached storage without the need of any upstream SAN switch as we have zoning capabilities in UCS now.

In short, for any direct attached storage, you need to have FI in FC switch mode.

-Ganesh