Native FC on N2348UPQ interoperability matrix

[mklas]

Hello, team,

please, let me kindly ask the question regarding the formally published storage interoperability matrix for native FC interfaces hosted on unified Nexus 2348UPQ FEXes parented by Nexus 56xx Series switches. It seems that the recently published interop document posted on:

http://www.cisco.com/c/en/us/td/docs/switches/datacenter/mds9000/interoperability/matrix/intmatrx/Matrix1.html

does not provide any Nexus 2xxx specific interoperability details for native FC connectivity, there is even no FC HBA listed as supported with regards to N2348UPQ.

Is it safe to use parent switch (N56xx in this particular case) interoperability matrix as a formal guidance or do you plan to update the interop matrix with N2348UPQ native FC details in the near future?

Many thanks!

Sincerely,

Marian

[Walter Dey]

Hi Marion

As you can see form the FEX datasheet

http://www.cisco.com/c/en/us/products/collateral/switches/nexus-2000-series-fabric-extenders/datasheet-c78-731663.html

there is no native FC support, only FCoE !

Walter.

[mklas]

Hi, Walter,

unfortunately, this is obviously an incorrect claim.

Native FC is indeed available on Nexus 2348UPQ FEX parented by Nexus 5600 since 7.3(0)N1(1), it is documented even within the FEX datasheet you've referenced to and is is clearly mentioned in the respective release notes:

http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5600/sw/release/notes/7x/Nexus5600_Release_Notes_7x.html#82944

with configuration guide available here:

http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5600/sw/fcoe/7x/b_5600_FCoE_Config_7x/configuring_unified_fex_with_fc.html

Therefore, let me please kindly return back to the original question - Is it safe to use parent switch (N56xx in this particular case) interoperability matrix as a formal guidance for Nexus 2348UPQ native FC designs or do you plan to update the interop matrix with N2348UPQ native FC details in the near future?

Thank you!

Sincerely,

Marian

[Walter Dey]

Hi Marian

Sorry, my fault ! you are of course right ! Question is, if the FC vendors like EMC, IBM, HP and HBA vendors support it or not. 

Cisco and their interop matrixes are sometimes not in synch.

FC is quite a delicate issue if it comes to interoperability.

[mklas]

Hi, Walter,

it is, indeed! This is the main reason I am seeking the official guidance from Cisco in order to avoid any speculations and unbacked assumptions.

Sincerely,

Marian

[Walter Dey]

Hi Marian

I think the most ciritical factor is oversubscription: e.g. a 16G HBA expects a nonoversubscribed pipe. With this FEX, assuming 6 x 40 uplink, you have 3:1 oversubscription ! which is not acceptable.

I would also compare the FC features of a Nexus 56xx, versus a MDS SAN OS, which are not 100% equal. 

[mklas]

Hi, Walter,

16G FC is supported on max. 24 FEX HIF ports. If you set the odd interface to 16Gbps FC mode, the neighboring even interface should be put into "out-of-service" state. It means worst case oversubscription is close to 1:1.5 more likely considering 6x 40GE active uplinks.

I certainly do not want to put an equal sign between native FC port on N2348UPQ FEX and a native FC port on N5672UP-16G or even MDS9k Series, neither feature-wise, nor performance-wise. However, Cisco declares native FC interfaces on 2348UPQ FEX a valid and supported solution, so one could hardly get surprised if customers and solution designers got attracted by this design alternative and if they are actively seeking additional details related to the solution - including interoperability details.

Thank you!

Sincerely,

Marian

[Walter Dey]

Hi Marian

My understanding is that this FEX FC functionality is a FC NPV switch, connecting to a NPIV (Nexus 56xx).

NPV switch is a confusing term; it is not a switch, therefore no local switching; flogi happens on the upstream NPIV switch.

The FEX NPV is essentially a HBA dumb fan in !

So from that point of view, FEX not being a FC switch, interop requirements are much relaxed. Works like a hardwired HBA concentrator.

[mklas]

Hi, Walter,

running N5600 Series parent switch in NPIV mode is not required, you may run it either in regular FC switching mode or NPIV if your design does require it for NPV devices attached directly to N5600 node (e.g. not via FEX ports, since connecting NPV devices to FC HIFs on FEX is not supported). My perception (I am just guessing here) is that Cisco's proprietary VN-Link technology used for Ethernet HIFs is used for Fibre Channel HIFs as well (with or without any modification, I do not know), e.g. FEX does not represent NPV device with its FC interfaces, FC HIFs are considered "extended" ports, e.g. "local" ports from the parent switch point of view. Therefore I'm wondering if we might use N5600 Series interop matrix as a reference.

Sincerely,

Marian

[Walter Dey]

Hi Marian

100% agree ! FEX FC ports are like local Nexus 65xx FC ports; the same would be true, if FEX = NPV ? which it is not. 

NPV is FC Standard, FEX FC implementation seems to be proprietary; therefore limitations like no vsan trunking,.......

I would use the Cisco interop matrix for Nexus 65xx, checking however the storage vendors interop matrix, to see if they have some comments about FEX support.

[Henry_Shen]

Hi Marian:

    I had the same problem , if N5K-5672-16G +N2K-2348UPG , 2348UPQ HIF interface support 1.2.4.8,16G FC, about the matrix doc support list ,  N2K-2348UPG not support HBA card , so can i use 2348UPQ HIF port +16g FC GBIC connection with HBA card +16GFC GBIC Device or not ?