DCB (Data Center Briding) and Windows Server 2012 R2?

[Boudewijn Plomp]

I have a question about DCB (Data Center Bridging) in combination with Windows Server 2012 (R2).

We recently deployed a Cisco FlexPod. We use boot form iSCSI and also configured QoS, Jumbo Fames, no drop policies and all required parameters on UCS and our Nexus switches. According one of the Cisco white papers you should install the DCB (Data Center Bridging) feature on Windows. This sounds very promising as it offers communication based on DCBx which including PFC (Priority Flow Control), ETS and etc. After installation there is a LLDP driver present on the converged network interfaces. When I run the available PowerShell commands I can see the server is in a "Willing" state, but as far as I can see there is not other information been exchanged. I checked our Nexus switches and I see they communicate with DCB on UCS port-channel interfaces.

I prefer to enable end-to-end DCB communication with Windows, UCS, Nexus and NetApp. Since I can't find the right information this leaves me with a lot of questions:

• My first question is; Can it work and how does UCS exchange information with Windows Server 2012 (R2).
• Do we need to configure anything in Windows other than installing the DCB feature?
• The iSCSI interfaces (that use iSCSI overlaying vNICs) don't have the LLDP and default QoS driver available to bind. Can they still benifit from DCB? Does every interface need to communicate individually?
• What is the best practice to enable end-to-end DCB communication with Windows, UCS, Nexus and NetApp?
• As far as I can see NetApp does support DCB. Any recommendations?

I hope someone can provide us with some information. And I hope this answers some questions other might have as well.

[tcerling]

I think it pretty much depends on where you want to manage your converged environment - in UCS and Nexus or in Windows Server.

Here is a statement directly from Microsoft's Technet - "If you prefer to manage DCB from a switch you don’t need to install DCB as a feature in Windows Server 2012."  (DCB was introduced in 2012, but nothing has changed with 2012 R2).

When I look at what Microsoft is offering, it does not appear to be anything that we cannot already handle.  Again, from Technet - "DCB provides hardware-based bandwidth allocation to a specific type of traffic and enhances Ethernet transport reliability with the use of priority-based flow control. Hardware-based bandwidth allocation is essential if traffic bypasses the operating system and is offloaded to a converged network adapter, which might support Internet Small Computer System Interface (iSCSI), Remote Direct Memory Access (RDMA) over Converged Ethernet, or Fiber Channel over Ethernet (FCoE). Priority-based flow control is essential if the upper layer protocol, such as Fiber Channel, assumes a lossless underlying transport."  Isn't that what we already do with UCS and Nexus?  So do you want network administrators to work with Cisco tools or do you want them to have to work with Windows PowerShell?

[Boudewijn Plomp]

I find it a bit confusing, as Cisco writes to install it it in their previous and brand new white paper (page 117):

FlexPod Data Center with Microsoft Hyper-V Windows Server 2012 with 7-Mode

http://www.cisco.com/en/US/docs/unified_computing/ucs/UCS_CVDs/flexpod_mspc_hvws12.pdf

The information that I can find on the internet tells me it exchanges information between datacenter devices to make sure an end-to-end configuration is been set for serveral features. Including features like PFC. The devices must be "willing" to exchange this information.

[tcerling]

It looks like a typo to me.

That is the ONLY place it occurs in the document.  It is part of a PowerShell cmdlet to add features to the Windows Operating system.  The explanation of what the PowerShell cmdlet is supposed to do is to install the Failover Clustering and MPIO features - no mention of Data Center Bridging.  And, since there is nothing else in that entire document that talks about DCB, and there is a fair bit of talk about Failover Clustering and MPIO, the inclusion of the DCB feature in that PowerShell cmdlet seems quite out of place.  Hence, my guess that it is a typo.

I work with the author of that document.  I'll check to see if this was an oversight or if there is some reason why they included it.

[Boudewijn Plomp]

Any update?

[tcerling]

Sorry for the delay.

It was a typo - DCB is not needed.