vDS Design Considerations

fluk3d

After taking a quick peek at this article, I see that in certain circumstances it may be ideal to use a single VDS however; have you guys encountered situations where using multiple VDS is beneficial? I guess it would depend on the client requirements, and the back-end infrastructure but; with everything going converged with 10GbE the norm is single VDS.. any input would be great

Essendon

Havent come across an environment that uses multiple vDS's, but here's a link I found:

https://communities.vmware.com/thread/435467?start=0&tstart=0

dave330i

Security policy would be one reason. Another is ease of administration. Harder for admins to screw up the uplinks if there's less per vDS.

meadIT

I've used different VDS's when designing the networking for UCS environments. This allowed me to control what traffic leaves the UCS fabric.

Example: Let's say you have a single VDS set up with multiple uplinks on both fabrics. A virtual machine that is using a vNIC on fabric A needs to communicate to a VM on fabric B. This traffic would have to travel from the host A --> fabric interconnect A --> northbound switch --> fabric interconnect B --> host B. Alternatively, if you break out virtual machine traffic to its own VDS, you can configure the VDS to use fabric A as Active and fabric B as standby. This would allow traffic between virtual machines to stay completely inside the UCS fabric. The same example above, traffic would go from host A --> fabric interconnect A --> host B.

blargoe

I hadn't thought about the scenario meadIT presented before, security and (if there are lots of uplinks) administration are the only reasons I ever really considered. I normally go with one vDS.

QHalo

I've seen 1 vDS and 1vSS before, but not two vDS'.

meadIT

One of each is usually done to keep infrastructure traffic (management, vMotion, iSCSI, NFS, etc.) separate from the virtual machine traffic. This way, if something gets messed up on the VDS, you still have access to the host management to fix the issue.

fluk3d

These are great examples!