Should I connect ESXi hosts to a FEX?

[Marcel Kamenz]

I'm still confused.

before short time a VMware coach told me that a esxi host should'nt be connected to a fabric extender. reason: a fabric extender my not be connected to a switch. (the vmware dvs)

but since I try to design this datacenter   I do not know what to do right here. the requirement is that the esxi hosts to be redundantly connected to the network with 4x 10GE (2x production, 2x vMotion). Management and ILO should be connected to 1GE.

what would you do?
my plan was a pair of 5500 or 7009 in the network-rack as parents and in the racks two FEX as a top-of-the-rack in the server racks.
This design then for each row of racks in the data center.

Or do I have to use a pair of 5500 as ToR in each rack? In only talk about the access layer, the core or layer 3 is utilized by nexus 7000 or 4500/6500

The coach justified his statement with the official design guides from Cisco out there and that there are queue/asic/buffer limitations on 

I know that there are many different design with VM-FEX or 1kv,.....but I did'nt find anything about this requirement:

CUSTOMER WANTS TO CONNECT ESXi HOSTS TO FEX WITH DEFAULT DVS ON THE ESXi HOSTS.

Help please :)

[Walter Dey]

Hi Marcel

There is no single Cisco design best practise that recommends FEX connectivity of servers. The main reason is oversubscription; ESXi requires non blocking 10G Ethernet; see e.g

http://www.cisco.com/c/en/us/products/collateral/switches/nexus-1000v-switch-vmware-vsphere/white_paper_c07-607716.html

 https://www.vmware.com/files/pdf/support/landing_pages/Virtual-Support-Day-Best-Practices-Virtual-Networking-June-2012.pdf

 https://www.vmware.com/files/pdf/products/nsx/Design-Guide-for-NSX-with-Cisco-Nexus-9000-and-UCS.pdf

Walter.

[Marcel Kamenz]

Hi Walter,

that helps a lot. The problem of oversubscription should be the piece to keep in mind while design ESXi PODs with FEX.

So the best would be to have 5500er installed in ToR-Design instead of a FEX.

In my understanding the usage of FEX for 10GE ESXI hosts is a budget decision because of the oversubscription and so on, RIGHT?

[Walter Dey]

Hi Marcel 

Correct; it's only a matter of Capex ! 

Walter.