How does a Flex-10 port know which pNIC is a broadcast frame destined for?

[chuckk281]

Chris was looking to understand Flex-10 technology better:

**************************

Another curiosity question:

How does a Flex-10 port know which of the 4 pNICs on this port is a *broadcast* frame destined for when it receives one forwarde by a Virtual Connect Flex-10 module?

If that was a regular frame then the destination MAC address uniquely specifies the destination pNIC, but not for broadcast or multicast.

And the VLAN might have been stripped if that is a port defined in server profile as single  network port.

I cannot think of any mechanism other than some sort of additional signalling like a 4 bit pNIC mask send with the frame.

***************************

Bala responded:

*********************

Chris,

“Flex 10 Technology Brief” document describes the frames are double-tagged.  

The traffic to each FlexNIC is isolated using outer tag set by the VC and managed within the VC domain by the VC and the Flex LOM device.

Quote “Packets that have been tagged and isolated by VC and the FlexNICs then move from the Flex-10 device (LOM or mezzanine card) to the Flex-10 VC Enet module on a single pathway. This pathway is enabled by implementing the 10GBase-KR (IEEE specification 802.3ap) one lane, serial backplane connection standard.”

**************************

And Chris replied:

******************

Thank you.

This makes it perfectly clear.

*****************************

Any other comments or questions?