10G Ethernet and FCoE ports - Whats the diff?

[muthumohan]

Hi All,

I know what FCoE is and all that stuff. My only confusion is when we say that Nexus 5K ports can be configured either as 10G Ethernet or FCoE ports, what that actually means? All Cisco video data sheets say this.

I know Nexus 5K supports FCoE as a switch. But, why would they say the ports can be configured as FCoE? If a physical port supports Ethernet, then it must also support FCoE frames, right? After all, FCoE frames are Ethernet frames carring is just another payload type (FC, EthType = 8906). So, for Ethernet, FCOE frames are just like any other traffic. What is special about a port being said as FCOE enabled port?

My own answer to is this. If the port is FCOE capable, it will look into the incoming frames and if Ethtype is 8906, it will forward to the FC part of the N5K. If any other EthType, forward it the LAN side of the N5K. Is this corret?

Also, if an Ethernet Switch is DCB capable, that is, CEE, do we call this as FCoE Switch? This switch is not going to open the Ethernet frames.

Looks like these definitions are not clear...

Would appreciate any help in clarifying this.

Thanks and Regards,

Mohan

[richbarb · Accepted solution]

Hello Mohan,

In the Nexus switch when you bind a virtual FC port to a physical port, the switch knows that port will now process FCoE frames.

For the Nexus switch is pretty simple to identify a FCoE frame from another frame, just looking the Ethertype as you said.

When a frame comes in the switch port, the asic checks the ethertype of the frame, if a 0x8914 (FIP) or 0x8906 (DATA) ethertype match, then this frame will be processed by the SAN built in switch.

The DCB is the correct term, using by IEEE. The CEE as far I know is a IBM terminology that supposed have te same features of DCB. To be correct look for DCB capability and you will know that device can support FCoE.

Lastly, be aware, just because the box is "DCB capable", it not means have FCoE implemented. The DCB is just a requirement to you run FCoE in your product.

Regards,

Richard

[muthumohan]

Thank you Richard. I appreciate your quick response.

What you said is what I was thinking, no document clearly said that. Thank you again.

Yes, DCB is correct term and yes, DCB capable does not mean FCoE capable.

Just one more thing about this Nexus 7000 Storage VDC. The documentation says that N7K has FCoE capable ports, but it is not a 'Fibre Channel' switch. If you have virtual Fibre Channel (vFC) ports in a switch, does it not become a FC switch? I know it does not have native Fibre Channel Ports on it, but having a vFC should make it as a FC switch as well, right?

Regards,

Mohan

[richbarb]

Yes, the Nexus 7000 is not considered a full SAN switch just because it doesn't support native fc ports.

A SAN switch should support native fc port, besides you may run your SAN completly with FCoE, the industry doesn't consider it a full san device, probably just because fc is still the protocol most used.

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