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Traffic Flow


Traffic Flow



Short Question:

Two Flex10 Modules in Bay1 and Bay2.

3x BL460G7 Server

VC Configuration is active/active

In a server to server communication (like vmotion) i need to know if it is possible to keep the traffic inside the enclosure when you have an active/active configuration?

I know in an active/standby configuration the traffic from one server to another will stay enclosure internal.



Respected Contributor

Re: Traffic Flow

You would need to create a vNet that is not connected to any uplinks; that would ensure that all traffic stays internal.


By default the VC's will keep traffic internal unless the stacking links are saturated.  Then it would go out to the switch and back down.


Re: Traffic Flow


Trusted Contributor

Re: Traffic Flow

The answer is slightly more complicated.


In an Active/Active you basically split things into Left and Right sides.

If the Source and Destination NICs are both "Left" side, then even in Active/Active the traffic will stay inside.

Same is Source/Destination are both Right side.

Howerver if by chance you have Source left and Destination right then traffic will exit, cross over the upstream switch infrastructure and then back down.


As far as traffic leaving when the Stacking links are saturated in an Active/Passive, I have never heard of such a thing.

The MAC address you want to talk to get learned from either the stacking port or the uplink port and like any other switch it makes the delivery decision based on the MAC address and what a Cisco shop would call the CAM table.

Since traffic can only egress through a single module at a time in Active/Passive, it seems highly impossible the traffic would somehow go through the uplinks.  And with a "Ethernet Network" that has no uplinks its physically impossible.


Lastly, keep in mind you can mix and match as of 3.30.

One uplinkset can be Active/Passive and use certain uplink ports.

Then you can have another (2) Uplink Sets that are Active/Active and use different uplink ports.

You can then mix and match within the server profile.

This uses more uplink ports but allows more granular control of whether a Network is better suited for Active/Passive (East/West ala vMotion) or Active/Active (North/South ala iSCSI or any traffic going through Layer 3)


Re: Traffic Flow



So if I have a vSphere host using 2 FlexFabric modules in Active/Active mode with each of the vSwitch cesonfigured to use a pair of Flex NICs (1 from each FlexFabric) in vSphere active/active config.


I a VM that gets associated with  FlexFabric A side will need to go through the uplinks to communicate with a VM on the same vSwitch that is associated with FlexFabric B?