VM-FEX and Nexus 1000v relation

[AhmedBassiony]

Hi

I am a new in virtulaization world and I need to know what is the relation between Cisco Nexus 1000v and Cisco VM-FEX?, and when to use VM-FEX and when to use Nexus 1000v.

Regards

[Keny Perez · Accepted solution]

Ahmed,

Nexus 1000v is a Distributed Switch that will let you manage your VEMs, see that relation like a Supervisor-LineCard relation.

VM-FEX gives you the option to bypass the vSwitch embedded on each ESXi host (VEM) for example.

With VM-FEX you see the VMs as if they were directly connected to the Parent switch (N7K/5K for example), making the parent switch reponsible for the management (cause there is no vSwitch in the middle anymore).

This is a good topic that can be discussed and is hard to sum up in just a few lines, have you read something in specific? any questions or doubts that we can help you clarify?

-Kenny

[AhmedBassiony]

Hello Keney

Many thanks for your reply, I need to know When can I use Nexus 1000v?, and When can I use VM-FEX?. Also I need to  understand the physical connection for Nexus1000v appliance?

Regards

[Keny Perez]

Ahmed,

Sorry for taking this long to get back to you.

Nexus 1000v is a virtualized switch and as such will require that any traffic coming in or leaving the VM will first need to pass through the virtualization layer, therefore causing a minimum delay that for some applications (VMs) can be catastrophic enough that may mean too much delay.

With VM-FEX you gain the option to bypass the virtualization layer with for example "Pass-Through" mode where the vmnics are really assigned and managed by the OS, minimizing the delay and making the VMs look as if they were directly attached, also, this offloads CPU workload in the mean time, optimizing the host/VM's performance.

The need for one or the other will be defined as always by the needs your organization/business has.

Benefits of VM-FEX (from cisco.com):

• Simplified operations: Eliminates the need for a separate, virtual networking infrastructure
• Improved network security: Contains VLAN proliferation
• Optimized network utilization: Reduces broadcast domains
• Enhanced application performance: Offloads virtual  machine switching from host CPU to parent switch application-specific  integrated circuits (ASICs)

Benefits of Nexus 1000v here on another post from Rob Burns:

https://supportforums.cisco.com/thread/2087541 

https://communities.vmware.com/thread/316542?tstart=0

I hope that helps 

-Kenny

[Walter Dey]

I add a few important things

     - VM-FEX also uses the same VEM module like N1K; however, per ESXi host, you can only do VM-FEX OR N1K, but not both. VEM works in local switching mode (N1k) or path through (VM-FEX)

     -VM-FEX is ethernet only

     - VM-FEX supports vmotion, but only within one UCS domain (yes, there are hacks to do it between different domains, but no TAC support)

     - Regarding performance gain; application dependent; however, the SAP community is very much interested in VM-FEX, see eg. http://www.cisco.com/en/US/solutions/collateral/ns340/ns517/ns224/ns944/whitepaper_c11_703103.pdf

http://www.redhat.com/rhecm/rest-rhecm/jcr/repository/collaboration/jcr:system/jcr:versionStorage/9755a4ed0a0526011df999be4d5d96a7/180/jcr:frozenNode/rh:resourceFile

http://de.slideshare.net/CiscoTurkey/all-about-saponciscoankara

Walter.